Assembly Automation Journal

ISSN 0144-5154

AssemblyAutomationThe international journal of assembly technologyand management

Volume 22 Number 3 2002

www.emeraldinsight.com

aa_cover_(i).qxd 14/08/2002 11:17 AM Page 1

Design for assemblyGuest Specialist: Dr Mauro Onori

Contents

199 Access to Assembly Automation online

200 Abstracts & keywords

202 Editorial

Viewpoint

203 Product design as an integral step

in assembly system development

Mauro Onori

Company news

206 A review of the latest developments in

the industry

Features

215 Delphi expands diesel injector

output using automated assembly

John Mortimer

223 A new wave of synchronous robots

Anna Kochan

226 US National Manufacturing Week

Dick Bloss

230 Trends in the robotic simulation

industry

Greg Ahrens and Gord Pageau

235 Robots great and small at

Hanover

Anna Kochan

Research articles

239 Assembly-initiated production –

a strategy for mass-customisation

utilising modular, hybrid

automatic production systems

Anders Karlsson

248 Shortening the design for

assembly process time for torque

converter development

Y.J. Lin and Adam Uhler

260 Geometric variation prediction in

automotive assembling

C. Xiong, Y. Rong, R.P. Koganti,

M.J. Zaluzec and N. Wang

270 Dimensional variations during

Airbus wing assembly

M. Saadat and C. Cretin

Assembly Automation

Volume 22, Number 3, 2002 ISSN 0144-5154

This issue is part of a comprehensive multiple accessinformation service comprising:

Paper format

Assembly Automation includes four issues in

traditional paper format. The contents of this

issue are detailed below.

Internet Online Publishing

with Archive, Active Reference Linking,

Research Register, Non-article Content,

Institution-wide Licence, E-mail Alerting Service and

Usage Statistics.

Access via the Emerald Web site:

http://www.emeraldinsight.com/ft

See p. 199 for full details of subscriber entitlements.

Contents (continued)

277 FAS scheduling based on

operation flexibility

Rong-Lei Sun, Youlun Xiong,

Runsheng Du and Han Ding

Mini features283

. Delphi uses Negari system to

support lean manufacturing and

provide production flexibility

. PHASA assembly is key to

productivity

. Moving parts can be built

pre-assembled by automated

prototyping system

. ElectRelease – electrically

dis-bonding epoxy

. Pedal power through laser

transmission welding

. Yellow goods laser

. AGCO schedules tractor assembly

with Tecnomatix eM-Power

sequencer

New products

290 Updated information on the latest

entrants to the industrial robotics

market

Internet page296

What is new and available through the

Internet

298 Book reviews

300 Patent abstracts

302 Diary

Flexible scheduling

Design for assembly is a recurrent theme for

this journal but up to now we have

concentrated on the physical design of the

product, what fixturing methods should be used

and other associated fabrication techniques.

These aspects are clearly of critical importance,

however, of equal importance is the assembly

system that has the job of assembling the final

designs.

Designing your assembly system so that it is

able to assemble your products is the main

theme for this issue. If you only have one

product then life is simple, however, if you

have a variety of different products or a

number of product variations then life

becomes more complex. The trick in such

situations is to design your assembly system

so that the various assembly stations (manual

or automated) are kept busy, while at the

same time reducing stock holding and

speeding up order fulfilment. This requires a

system that is highly flexible and can respond

instantly to changes in demand and also

accommodate machine breakdowns and stock

shortages as efficiently as possible.

A really flexible system will be very complex

and sophisticated in its operation. It will need

to have detailed knowledge of orders, stock,

assembly operations required by each

product, assembly station capabilities and

setup times, physical location of all

sub-assemblies and transportation facilities,

and delivery schedules.

Given that you have the component parts

and assembly systems that are capable of

assembling them, then anyone can get into

production. However, the difference in

productivity between an ad-hoc assembly

programme, and one that flexibly responds to

manufacturing requirements is considerable,

and well worth the additional effort required

to create it.

The time to come up with such a system is

not (if you can help it) after the factory layout

has been completed, but is, instead, best done

concurrently with the plant design. One key

part of a flexible system is the ability to

transport components and sub-assemblies

quickly to the next assembly station. If items

in build are continually being moved in and

out of storage then productivity and stock

holding and delivery schedules will all suffer.

All of the above is very obvious and yet

most companies would benefit from a

serious reappraisal of their manufacturing

systems. All too frequently many decisions

will be made by production managers who

make the best decisions they can based on

the current situations. My argument is that

in most cases the variables involved are

simply too complex for a person to handle in

the best possible way, however, the required

‘‘what if’’ calculations are precisely what

computers are good at, so it makes sense to

use them for the task.

Creating such a system will not be easy, but

the potential gains are well worth the effort.

Clive Loughlin

Calls for papers

Assembly Automation, Vol. 23 No. 1 –

Bin picking and flexible gripping

Grasping randomly oriented parts. Flexible

grippers and gripping strategies.

Copy deadline: 13 October 2002.


Adhesives, welding and gluing

Latest developments in parts joining without

the use of fasteners.

Copy deadline: 14 December 2002.


Machine vision and inspection

Latest developments in machine vision and

automated inspection. Concentrating on

applications in automated assembly systems.

Copy deadline: 25 March 2003.


Rapid prototyping and rapid

manufacturing

New methods, materials and systems for

rapid prototyping and rapid manufacturing.

Copy deadline: 8 June 2003.

202

Assembly Automation

Volume 22 . Number 3 . 2002 . p. 202

# MCB UP Limited . ISSN 0144-5154

Editorial

Product design as anintegral step inassembly systemdevelopment

Mauro Onori

Design for assembly (DFA) techniques and

methodologies have been in use since the

early 1980s, and the term itself no longer

arouses particular ambiguities. Not only has it

become a known methodology, it has led to

the uncontrolled spawning of myriad other

approaches, including design for variance,

design for automatic assembly, design for

reliability and so forth. The development of

such a wide variety of design support tools is,

in itself, a proof of the validity and value of

such tools but, nonetheless, their use has not

truly been as widespread as intially expected.

Major companies have, to varying degrees,

applied the technology and obtained

quantifiable results. Other corporations have

even gone as far as to develop their own forms

of DFA, and academia has expanded the

realm to encompass the modularisation of

products as well. In view of such a positive

evolution of events, it becomes legitimate to

wonder why there still exists a rather

widespread difficulty, for most companies, to

adapt their production range and rates to new

market needs. The answer may lie in two

separate domains. The applicability of these

methods has often encountered resistance by

the designers or design team, primarily

because further learning is required and,

secondarily, because the methods are

sometimes viewed as a limiting factor for

creativity. The other answer is less obvious

and may lie in the fact that the coupling

between product design and production

system has not yet been fully exploited.

The applicability factor of DFA methods

has received considerable attention.

Flowchart methods which avoid extensive

mathematical analyses have been presented,

such as the design for automatic assembly

(DFA2), and concurrent engineering

methodologies have proposed supportive

measures. By and large, one may say that

greater efforts may not result in major

changes since the main hurdle still remains

the distinct separation which exists, in most

companies, between the design departments

and production system developers. In

essence, this is a management issue. The

cultural, organisational, and information flow

barriers must be brought down as a

well-established strategic measure. All

methods include consequences and

implications for the production, both

upstream and downstream. These

implications may imply that the use of any

The author

Mauro Onori is Associate Professor, WoxenCentrum/

Assembly System Division, Department of Production

Engineering, The Royal Institute of Technology,

Stockholm, Sweden.

Electronic access

The research register for this journal is available at

http://www.emeraldinsight.com/researchregisters

The current issue and full text archive of this journal is

available at

http://www.emeraldinsight.com/0144-5154.htm

Viewpoint

203

Assembly Automation

Volume 22 . Number 3 . 2002 . pp. 203–205


DOI 10.1108/01445150210436392

DFA method may not give the expected

results if the entire chain of events is not

considered. At the end of the day, concurrent

engineering is more than a methodology or

philosophy, it should actually be regarded as

an organisational working strategy. This lack

of simultaneous development work is

probably one of the main causes of the

drawbacks denoted by modern assembly

system solutions.

The major problems encountered by

companies dealing with assembly mainly

relate to uncertainty. First, it is very difficult

for companies to predict the type and range of

products that will have to be developed. The

second uncertainty regards the production

volumes and lifespans reached by these future

products. The overwhelming reaction to these

problems has been partially strategic, by

employing DFA and similar methods, but

primarily technical: that is, to attempt to

develop extremely flexible assembly machines

that attempt to adapt themselves to different

product families and production scenarios.

This has led to a series of multi-purpose

machines, often classed as flexible automatic

assembly (FAA) systems. Another approach

has been to focus on the standardisation and

modularisation of high-volume manual

assembly lines, requiring advanced control

solutions and special robotic cells for the

automatic tasks. The common denominator

to these approaches has been the dream of

flexibility, a focus which has inadvertently

avoided the actual assembly process and

product design considerations. This fact has

been further aggravated by the fact that a firm

grasp of which type of flexibility is being

targeted has, until recently, been neglected in

favour of a general, yet vague, description of

this term. Unfortunately, this existing

paradigm of highly flexible assembly systems

still prevails and results in expensive, highly

technological solutions which cannot easily fit

into existing production facilities, rarely

accomodate an analysis of the product design

implications, require technological

competence, and are seldom able to assemble

more than one product generation. Although

fairly adequate to many different product

types, they fail to be very performative in any

domain.

The somewhat hidden problem, however, is

that the major part of producing companies

have to deal with planned products and existing

production facilities. Ideally, they would like

to fit any new product, or product variant,

into an existing assembly system with as low

costs as possible. To date, this has only been a

dream. The common scenario is that the

existing production system principles still

dictate, to a varying degree, the basic design

requirements for future products, and vice

versa. Basically, there is a strong dependence

between product development and selected

system principle (parallel flow, serial line,

etc.). This entails that any new FAA, or other

assembly system solution, has to fit into an

existing facility. The same applies for a new

product design. For example, as soon as a

new product design is assumed to require a

new assembly system solution, a serious

analysis of the components is required to

ensure that the targeted volumes, costs, etc.

are attained. This often leads to a change in

some system component, or product part, to

enable the achievement of the goals. This is

exactly where the problems arise: the

maximum attainable capacity and flexibility

of an assembly system are ultimately dictated

by the product design and assembly

equipment. Therefore, if the equipment

cannot easily adapt to changing market

requirements and/or new products, the

overall flexibility is greatly reduced.

Furthermore, if the envisaged assembly

system solution cannot easily fit into the

existing production system scenario, it will

not be deemed as fully flexible by the user. A

focus on assembly system solutions as a

separate entity to the actual product designs

will therefore not succeed.

This vital link between product design and

production system is on the verge of

becoming even more crucial since new trends

and developments are emerging. Although

digital plant technology, or virtual factory

solutions, are aware of this link and are

struggling to achieve an information flow

between the two domains, the products and

technology around them are drastically

changing. Eco-reliability, or sustainability,

has become even more important and must be

embedded in both product and system

design. The products themselves are

becoming ever smaller, inducing the

development of mini and micro factory

solutions, miniature systems which demand a

re-consideration of known methodologies and

approaches. Furthermore, since

miniaturisation will, in most cases, only affect

part of an entire product range, these

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Product design as an integral step in assembly system development

Mauro Onori

Assembly Automation

Volume 22 . Number 3 . 2002 . 203–205

solutions will have to be embedded within an

existing production system. Other trends,

such as the growing push for design for

reliability, further underline the need to assess

both product design and production system

aspects concurrently. In terms of assembly

systems, what is required is not a solution

which tries to accomplish all of the envisaged

assembly needs but, rather, a solution which,

being based on several reconfigurable,

task-specific elements (system modules),

allows for a continuous evolution of the

assembly system. In order for this to succeed,

however, a dynamic link to the product design

processes and methods must be created. In

short, the challenge for design engineers and

production system developers is to create a

common working platform.

Basically, the most innovative product

design can only be achieved if no assembly

process constraints are posed. The ensuing,

fully independent, product design and process

selection procedure may then result in an

optimal assembly system principle. The

optimal layout is then linked, via a

methodology, to a broad range of small,

process-oriented system components. All

dependency on existing assembly system

principles is broken. Consequently, one has

an evolvable assembly system principle (EAS)

(Onori, 2002) in which the existing assembly

system may dynamically adapt to the new

products, technologies, and production

scenarios. Consequently, the designers know,

a priori, if there are technical solutions

available to their designs and which particular

constraints they pose on these designs. The

ensuing assembly factory is, due to the

small-scale modularity and standardisation,

dynamically reconfigurable. This represents a

shift in thinking since it implies that

theoretically very flexible, multi-purpose cells

will be replaced by a highly flexible concept

consisting of several well-targeted but not, in

themselves, highly flexible components.

Hence the new paradigm.

The industrial and academic community in

Europe is already at work with such issues,

and networks such as the assembly net (http://

www.assembly-net.org/) and CE-NET(http://

www.ce-net.org/) are clear examples. The

challenge is not only to bring the assembly

system engineers to truly collaborate with the

product design experts, but also to adapt

DFA, DFR and all other methodologies to

encompass new engineering domains and

social trends, such as eco-sustainability,

microtechnologies and the rapid decline in

manual workforces. It is therefore no longer

an equivocable forecast to say that automatic

assembly, and the product design methods it

will require, will represent a key factor for

survival in future markets.

Reference

Onori, M. (2002), ‘‘Evolvable assembly systems – a newparadigm?’’, Proceedings of the ISR2002,Stockholm, October.

205

Product design as an integral step in assembly system development

Mauro Onori

Assembly Automation

Volume 22 . Number 3 . 2002 . 203–205

BMW pioneers robotic automation formounting gearboxes on engines

Keywords BMW, Automotive, Gearboxes,

Robotics

BMW has installed automation for

assembling gearboxes to engines. ‘‘It is the

first time this has been accomplished

anywhere in the world’’, claims Bernd

Bruckert of IBG, the systems integrator

responsible for developing the technology.

IBG delivered the first cell to BMW’s

Regensburg plant in February 2002 and will

follow it up later this year with another at

Dingolfing (see Plate 1).

‘‘Quality is one of the main reasons for

automating the assembly of the gearbox to the

engine’’, says Bernd Bruckert. It is a task that

is usually carried out by two operators using

an assist device to take the weight. However,

performed manually, it is difficult for the

operators to feel if they are positioning the

gearbox exactly right. ‘‘The tolerances are

very tight and the operators frequently cause

damage’’, he indicates, warning that, when

the operators do not get the position quite

right, they are likely to scrape off metal, which

becomes debris in the oil. As a result, there

could be engine noise and early gearbox wear.

By incorporating vision systems, IBG has

enabled the robotic solution to function with

maximum precision. One camera is mounted

on the robot arm itself and another is

stationary. The robot first uses vision to check

the position of the gearbox on its carrier

before picking it up. Then, once it has the

gearbox in its gripper, the robot shows the

gearbox to the second camera to determine its

exact position in the gripper. It then

approaches the engine and uses its on-board

camera to check the location of the engine.

Having recalculated its program to account

for the precise positions of both gearbox and

engine, the robot performs the assembly task,

putting two bolts in place to secure the

assembly. It achieves a tolerance that is tighter

than 0.1mm and completes the entire task in a

cycle time of just 50sec.

The BMW installation is based around a

standard Kuka robot, the KR 200 that has a

payload of 200kg. The technical innovation

lies in the gripper that IBG has fitted to the

robot to handle the gearboxes. Because of the

variety of gearboxes, each of which has to be

picked up differently (more than 25 different

ones are in use at the Regensburg plant), the

gripper is highly flexible. In fact, due to the

use of servo-controlled location points, a

single gripper is able to handle all models.

The location points are programmed to move

automatically to their new positions,

according to the production sequence.

BMW has purchased the rights to the

technology IBG developed for the gearbox/

engine assembly application and has applied

for a patent on it. It relates mainly to the

design of the gripper.

Several other vehicle manufacturers are

discussing the same application with IBG.

Bernd Bruckert is confident of selling a

further eight to ten systems within the next

two years. He believes that robots are making

a comeback in automotive assembly

applications. ‘‘The robot systems we have

today are faster and more accurate than even

a few years ago, and they are able to carry

heavier loads. It also makes a difference that

designers now take into account factors

relating to robotics and automation when they

do their designs’’, he comments. It is in the

final assembly line where Bernd Bruckert

expects to see the most significant increase in

Company news

Plate 1 Systems integrator IBG is supplying BMW with

the world’s first robot system for automatically

mounting gearboxes to engines

206

Company news Assembly Automation

Volume 22 . Number 3 . 2002 . 206–214

robotics in the next few years, particularly for

mounting interior components such as

cockpits, seats and roof trim.

Renault completes £240,000 follow-onorders for Tecnomatix eMPowersolutions

Keyword Production management

Tecnomatix Technologies Ltd, a leading

provider of manufacturing process

management software solutions, today

announced that the Renault Group has

purchased additional eMPower software

licenses valued in excess of £240,000 for use

in their Technocentre.

The Renault Technocentre brings together

in a single site all the teams responsible for the

design and development of new vehicles,

saving as much as £90 million in development

costs per vehicle, according to Renault’s

estimates.

Renault’s additional Tecnomatix

eM-Workplace and eM-OLP licenses will be

used in both the preplanning and detailed

studies phases of their automobile assembly

process. The eMPower products let Renault

improve the quality of its spot welding

process, reduce robot programming time,

define a workflow with line builders and allow

for reusability of existing resources.

Renault will continue using eM-Workplace

in the preplanning stage of production to

transfer 3D models and welding point

locations from the CAD system to the

production floor, conduct feasibility studies

for assembly process validation, provide cost

estimation support for production scenario

decisions, define the assembly sequences and

provide feedback to product design.

During the detailed studies stage, Renault

will be able to specify the required resources

and the available space for the lines or

workcells to be delivered. Renault will also be

able to give the line builder all technical

constraints and then request a complete

welding line/workcell study with paths,

fixtures, definition and off-line programming.

For further information, please contact:

Eric Gautier, Tecnomatix European

Headquarters. Tel: 00 (33) 134 58 24 24;

E-mail: [email protected] URL:

Internet: www.tecnomatix.com

Profibus becomes first Chinese fieldbusstandard

Keywords Profibus, Fieldbus, China

Profibus has become the first fieldbus to be

published as a Chinese professional standard.

Officially designated JB/T10308.3-2001,

Profibus is published by the China Machinery

Industry Federation, allowing it to be

specified by Chinese institutions for use as a

fieldbus technology in machinery and

automation.

This fact, together with the news that the

Chinese Test Laboratory in Beijing is now an

accredited Profibus test centre, means that

conditions are ripe for commercialisation and

sale of Profibus products and services in the

Chinese market.

With the successful accreditation of the

Chinese Profibus test laboratory in Beijing,

China, certification tests for Profibus devices

are now offered in eight international test

laboratories. The Chinese test laboratory is an

important institution to support

manufacturers of Profibus products in the

Asian market and to ensure the consistent

high quality standard of Profibus systems

throughout the world.

More information is available at: the

Profibus Group, 6 Oleander Close, Locks

Heath, Southampton, Hants SO31 6WG,

UK. Tel/Fax: +44 (0) 1489 589574; E-mail:

[email protected]; Web site, www.profibus.

co.uk

Assembly-Net precision assemblytechnologies for mini and microproducts

Keywords Assemblies, Precision, Assembly-Net

Assembly-Net thematic network is a unique

partnership in Europe, funded by the

European Commission (Project No. GIRT-

CT-2001-05039 ) to improve its global

competitiveness. The focus is on short

lifecycle products that require mini and micro

assembly solutions. Assembly-Net aims to to

bring together, share and exchange critical

technologies, research results, and the latest

information in precision assembly

automation.

By bringing together academic and

industrial partners (system vendors and

SMEs), the project partners have created a

network which can gather the relevant needs,

207


Volume 22 . Number 3 . 2002 . 206–214

available solutions, and research results in

order to organise assembly R&D efforts in

Europe. The network is expected to expand

and will focus on incorporating more SMEs.

The consortium currently consists of

members from ten countries. The consortium

intends to merge several national and

international research forums and already

includes a vast number of industrial members.

The prime aim is to share and exchange

information and the latest developments in

assembly system applications and design.

Assembly-Net aims also to facilitate the

formation of new, multinational projects in

precision assembly. The project is a forum for

special interest groups and a stimulus and

catalyst for the development.

The consortium consists of large and small

users of assembly systems, assembly system

providers, industrial consultancy groups, and

research institutes and universities. The

network partners cover a very wide range of

competence, including: assembly system

specification and design; assembly system

manufacture and supply; assembly system

use, both high and low-volume production;

development of flexible automatic assembly

systems; mini-assembly equipment

specification and design; disassembly system

specification and design; education in

assembly systems theory, application, and

design; and education in product design and

modularisation.

To join, visit the Assembly-Net Web site,

www.assembly-net.org, and fill in the

membership application form. Affiliated

membership of Assembly-Net is free. The

members may subscribe and unsubscribe at

any point during the life of the project.

Benefits include:. Access to special interest group

discussion forums (join in with the

debate).. Receipt of specially targeted broadcast

news items.. Automatic subscription to the newsletter

Assembly-Net coordinator is Dr Svetan M.

Ratchev, School of Mechanical, Materials,

Manufacturing Engineering and

Management, The University of Nottingham,

Nottingham, NG7 2RD; E-mail:

[email protected]. Tel. +44

(0) 115 9514018, Fax. +44 (0) 115 9514000

More information about the project can be

found at www.assembly-net.org (see Plate 2).

See also: Mauro Onori, Assembly Automation,

Vol. 21 No. 2, 2001, pp. 123-8, MCB

University Press, ISSN 0144-5154.

Simple effective direct computer linksfrom boardroom through to factoryfloor promised by £200,000 newIndustrial Ethernet Research Programme

Keywords Fieldbus, Product management

Researchers from the University of Warwick’s

Warwick Manufacturing Group are putting

together a £200,000 ‘‘industrial Ethernet

research programme’’ that will allow

technology and manufacturing companies to

use the Internet to create simple direct

effective computer links allowing control and

integration of technology on a factory floor

with every level of a business including the

boardroom.

The research draws on the successful,

widespread, use of low level industrial

computer networks (also known as

fieldbusses) which bring together intelligent

sensors, actuators, etc. with microcontroller

technology that did away with labour-

intensive, inefficient, wire-based factory

controls. This technology has already cut

installation and commissioning times by

75 per cent and drastically reduced the time

Plate 2 Assembly-Net aims to facilitate the formation of

new, multinational projects in precision assembly

208


Volume 22 . Number 3 . 2002 . 206–214

such equipment spends out of action when

problems occur and need resolving.

The companies using this technology have

longed to be able to take this technology a

step further by using Ethernet (Internet-

style communications) to develop

interfaceless communication through all

levels of an enterprise – from the shop floor

to the corporate network levels. Such a

system would provide an opportunity to

easily integrate the IT and factory floor

networking, providing substantial cost

savings. This allows users to link customer

and supplier data, reduce cycle time,

increase manufacturing reliability and

enhance customer satisfaction.

The new programme will draw on

techniques and languages such as extensible

markup language (XML) DirectX (a system

often used to drive computer games) and

electronic data sheet (EDS) to resolve the

technical issues of speed and reliability which

are key to developing practical applications of

this technology. They will also investigate the

real-time performance of Ethernet switches

and hubs on the shop floor.

Rockwell Automation UK, Tellima

Technology Ltd of Wakefield, and Warwick

Control Technologies Ltd are already funding

this £200,000 project and local companies

British Federal Ltd in Dudley, HM

Computing of Malvern, Dearborn Electronics

of Wolverhampton, and Contemporary

Controls in the University of Warwick

Science Park, are also in discussions with the

researchers.

For further details contact: Richard T.

McLaughlin, Senior Research Fellow,

Warwick Manufacturing Group, University of

Warwick. Tel: +44 (0) 24 76 524711 E-mail:

[email protected]

www.warwick.ac.uk/devicenet

New manufacturing system a ‘‘worldfirst’’ for UK

Keyword Holonic manufacturing

A revolutionary new approach to

manufacturing, which will benefit both

producers and consumers is being developed

by a unique UK-based alliance of commerce

and academe.

The University of Cambridge’s Institute for

Manufacturing (IfM), one of the world’s

leading centres for manufacturing innovation,

has joined with ‘‘smart’’ software expert Agent

Oriented Software (AOS) to create a

dedicated team which will work with major

manufacturing and logistics companies to

develop and implement ‘‘holonic

manufacturing’’ systems.

‘‘Holonic manufacturing is based on the

principle of treating a production process as

a set of individual, autonomous elements or

‘holons’ that combine to coordinate

operations right through from customer

order to despatch of goods’’ says Duncan

McFarlane, head of Automation and

Control at IFM. Once an order has been

placed, a set of instructions can be

electronically attached to the core part of the

product – for instance, the case of a mobile

phone, to ‘‘explain’’ how it will be made. As

the product moves through the factory, it

can in effect ‘‘ask’’ at each stage for the part,

peripheral or even colour of the front cover

or aerial that it requires.

‘‘This means that every product can be

automatically built to individual demands,

but eliminating the expense and delay of

traditional customisation, making the

concept a real boon to the consumer’’,

explains Andrew Lucas, MD of AOS.

‘‘However, the advantages to manufacturers

are also significant, for example beating the

competition to offer new products, being

able to offer a greater product range at the

same price, aiming for ‘zero stock’ on hand,

and reorganising quickly if there are

problems such as machine breakdowns. This

new approach is a ‘smarter’ way to

manufacture – it will help to make British

manufacturing more competitive, and better

able to make its vital contribution to the UK

economy.’’

The results of the work being undertaken

by the team are expected to become

commercially available within the next year,

and the new system is likely to be on many

factory floors by 2005. So the day that you

can order your new car or mobile, and it will

build itself to your specifications, is closer

than you might think!

For further information: Dr Andrew Lucas,

AOS Ltd. Tel: +44 (0)7867 806552; E-mail:

[email protected] or Dr

Duncan McFarlane, Institute for

Manufacturing. Tel: +44 (0) 1223 338069;

E-mail: [email protected]

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Volume 22 . Number 3 . 2002 . 206–214

ABB accelerates industrialIT programme

Thousands of products are now certified

to new standard

Keywords ABB, Production management

ABB has accelerated the certification of its

offerings under the ‘‘IndustrialIT’’ label.

Some 3,000 products have been certified as

part of ABB’s programme to simplify the

integration and operation of its entire range

of products for its utility and industry

customers. At year-end 2001, ABB had

certified 1,000 products, surpassing its

target of 800 products.

‘‘ABB’s technologies are rapidly evolving

under a single information framework that is

transforming our entire product line into an

integrated system of compatible ‘building

blocks’’’, said ABB president and CEO

Jorgen Centerman. ‘‘With IndustrialIT, our

customers can build tailor-made solutions for

their businesses, helping them improve their

performance.’’

IndustrialIT is ABB’s information

framework based on open industry standards.

It links ABB’s automation and power

technology products so they are easier to

configure, install, operate and maintain in real

time. The goal is to allow customers to

integrate industrial systems and information

technology by managing information about

plant, assets, operations and business

systems.

‘‘IndustrialIT-enabled’’ products from ABB

or its partners come equipped with software

containing detailed information about the

product – such as instruction manuals,

drawings, remote control faceplates and

configuration tools.

As each certified IndustrialIT product is

installed (for example, a sensor, robot, motor,

transformer, etc.), the software can be copied,

pasted and arranged into a customer’s

monitoring and control system. A simple

mouse click opens up the full array of

information needed to configure,

troubleshoot or optimize a given component.

ABB has also announced the first external,

non-ABB product to be IndustrialIT

certified, a suite of maintenance

management applications that form part

of IFS applications from Swedish software

producer IFS AB.

For more information contact: Bob

Kingman, ABB, Howard Road, St Neots,

Cambs PE19 3EU, UK. Tel: +44 (0) 1480

488207; Fax: +44 (0) 1480 218361; www:

[email protected]

Sprayforming goes with the flow

Keyword Rapid prototyping

Novarc, Europe’s leading exponent of

sprayforming for tooling, has announced a

joint programme with tooling and pressings

specialist Airflow Streamlines to develop its

technology for Airflow clients in the

automotive industry. Sprayforming, brought

to commercial reality by Novarc in

conjunction with Oxford University and

Ford, is set to both reduce the cost and

increase the speed of tooling production.

At present, Airflow is exploiting

sprayforming to produce tools for the

production of body in white panels. Tools

supplied have already shown a high degree of

wear resistance in press trial runs, due to the

robust physical properties of the steel shell

generated by the spray process.

Stewart Pearson, director and general

manager of Airflow Streamlines’ body

division, noted: ‘‘We are delighted to be

involved in the commercial exploitation of

sprayforming in the automotive arena.

‘‘At Airflow, we can see the obvious

potential of the technology and will be

working alongside Novarc to bring its rapid

tooling advantages to the benefit of our

clients. We are extremely optimistic about

prospects for the automotive sector over the

next 12 months and see sprayforming as

another string to our bow.’’

For further information contact: Novarc,

8a, Begbroke Business and Science Park,

Sandy Lane, Yarnton, Oxford OX5 1PF, UK.

Tel: +44 (0) 1865 849326; Fax: +44 (0) 1865

849327; www.novarc.com.

JAVA technology heads for the factoryfloor

Keywords JAVA, Automation

An international specification for real-time

data access (RTDA) is helping JavaTM

technology to elbow its way onto the factory

floor, J Consortium, Inc., has announced.

An open forum committed to advancing

Java technologies in real-time embedded

systems, the J Consortium published RTDA

to introduce Java into assembly-line

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Volume 22 . Number 3 . 2002 . 206–214

manufacturing. The specification focuses on

how to access data from such assembly-line

equipment as actuators and sensors under

tough time constraints. RTDA closes the gap

between Java technology and real-time

performance, allowing the use of Java

technology at the lowest level of factory

automation while preserving Java’s essential

nature of complete device independence.

For further information: http:/wwwj-

consortium.org

Billion-dollar Chinese shipbuilder toimplement 10,000 licenses of AutodeskInventor 3D mechanical design software

China State Shipbuilding Corporation

selects Autodesk software for a global

competitive advantage

Keywords CAD, Shipbuilding, China

Autodesk, a world leading design and digital

content creation company, today announced

that China State Shipbuilding Corporation

(CSSC), one of China’s top 100 enterprises,

will purchase 10,000 licenses of the Autodesk

Inventor Series over the next three years,

primarily for the use of Autodesk Inventor 3D

mechanical design software included in the

Autodesk Inventor Series. CSSC worked with

China Daheng Information Technology

Corporation, Autodesk’s Manufacturing

channel partner in China to select the

Autodesk software as its standard for digital

design.

China is the third-largest shipbuilding

nation in the world and entry into the World

Trade Organization has created an urgent

need to upgrade its shipping industry’s

technology infrastructure. Implementing

enterprise-wide IT and advanced digital

design solutions are necessary to improve

China’s competitiveness in the global

shipbuilding industry.

The collaborative capabilities of Autodesk’s

software will help CSSC promote digital

information exchange among ship design

enterprises and ship owners. CSSC also

anticipates that improved collaboration will

increase competitiveness throughout its

shipbuilding supply chain, improving quality

and enhancing results.

‘‘The advantage of low labour costs in

China cannot be undermined by low

productivity’’, said Qiu Huihui, vice president

of Information Industry and Investment

Development at CSSC. ‘‘Utilising advanced

and suitable information technology is one of

CSSC’s strategies to address global

competition. Cooperating with Autodesk has

created an environment for CSSC to fully

utilise the 3D design applications and

resources available from Autodesk.’’

‘‘Autodesk’s work with CSSC plays a

strategic role in supporting China’s policy of

adopting advanced technology’’, said Robert

Kross, vice president of the Manufacturing

Division at Autodesk. ‘‘Autodesk is

committed to working with CSSC and China

Daheng Information Technology

Corporation to ensure they are able to take

full advantage of the powerful functionality

offered by Autodesk Inventor 3D design

software.’’

Further information from: Tina Naylor,

Autodesk Ltd. Tel: +44 (0) 1483 462653;


Cognex inks agreement with Entivity forintegrating vision with PC-basedautomation and control software

Keywords Machine vision, Assembly

Cognex, a world leader in machine vision

systems, has signed an agreement with

Entivity, a leading supplier of PC-based

automation and control software, to establish

a cooperative effort for the development and

promotion of integrated PC-based control

software and machine vision solutions.

The two companies will work together to

specify and develop interfaces that will

simplify the integration of Entivity’s

award-winning Studio family of automation

and control software with Cognex’s

award-winning In-Sight family of machine

vision sensors. Entivity and Cognex will also

cooperate on the promotion and support of

these integrated solutions in a variety of new

markets and applications.

Entivity’s Studio product integrates

advanced control and information technology

with Microsoft Vision 2000 to give users a

complete automation software solution.

Built-in enterprise connectivity, productivity

analysis and transparent scalability across the

full range of Microsoft Windows platforms

dramatically accelerates automation

implementation. Studio is a fully extensible

open architecture automation and control

software development platform.

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Volume 22 . Number 3 . 2002 . 206–214

‘‘Entivity products are very successful in

information-intensive applications and

complex control applications incorporating

sequential logic, motion and machine vision

systems’’, said Ken Spenser, president and

CEO of Entivity. ‘‘Tightly integrated

advanced control and machine vision

improves control of the entire manufacturing

process for customers and system integrators

across a number of industries.

‘‘Our In-Sight machine vision sensors

provide manufacturers with feedback about

their product quality, process control, and

machine productivity’’, said Dr. Robert

Shillman, president of Cognex. ‘‘Entivity is a

world leader in taking PC-based control into

high value, information-intensive applications

and is a natural partner for us.’’

In-Sight vision sensors are low-cost, high

performance online inspection devices that

are used to automatically measure parts,

verify the correct assembly of products,

identify parts, and guide production

equipment. Ethernet communications are

built into most models, enabling users to

gather data to and from the image sensors and

put it on the same network as Entivity’s

PC-based control logic functions, helping

to speed the process of machine

troubleshooting. Operator and maintenance

personnel have the ability to check machine

flow and vision status from any of Entivity’s

Visio powered HMIs on the line, and share

vision results with all levels of the

organisation.

For further information contact: Katrina

Dixon, Cognex UK, Units 7-9, First Quarter,

Blenheim Road, Epsom, KT19 9QN, UK.

Tel: +44 (0) 800 0180018; Fax: +44 (0) 1372

726276; E-mail: [email protected]

OptoForm LLC established to pursueadvanced digital manufacturingopportunities


3D Systems Corp., a world leader in solid

imaging equipment, and DSM Somos, a

leading material manufacturer, announce the

official launch of OptoForm LLC, a new

company to pursue opportunities in the new

and expanding field of advanced digital

manufacturing (ADM), as conceived by 3D

Systems. ADM is expected to become a key

enabling technology for the customisation of

design and manufacturing, also called mass

customisation.

OptoForm LLC will deliver shop-floor

manufacturing solutions to the industrial

market based on composite plastic, ceramic

and metal materials using a proprietary direct

composites manufacturing process.

‘‘ADM will allow designers to reduce part

count in the design process thus reducing part

costs and assembly time. Designers and

engineers will be able to add custom features

and complexity to designs not currently feasible

with today’s manufacturing techniques’’, says

Grant Flaharty, executive vice president, global

business operations for 3D Systems.

‘‘The ability to manufacture a product

using additive fabrication techniques will

radically alter designs and manufacturing

methods over the next decade and beyond’’,

says Mervyn Rudgley, general manager of

OptoForm LLC. ‘‘Using ADM techniques

such as direct composite manufacturing and

other 3D systems technologies, existing

designs can be manufactured without the

costs and lead time associated with hard

tooling, and more complex designs will

become easier to manufacture.

‘‘We are pleased that we have the combined

resources of 3D Systems and DSM Somos, as

we begin our development program with

selected Fortune 100 industrial partners’’,

adds Rudgley.

Steve Hartig, vice president of marketing at

DSM Somos, says: ‘‘Over the next year we

expect to develop and test new materials that

will set new standards for structural

performance and capability in digital

manufacturing.’’

More information about the company is

available at: www.dsmdesotech.com and

www.dsmsomos.com

New application areas to promoterobust growth in advanced motioncontrol market

Keyword Motion control

Signs of optimism increase in the European

market for advanced motion control products

as flickers of light become visible in the

economic gloom and the array of end-user

applications in the industry diversifies and

drives market potential.

A new study by Frost & Sullivan (http://

motors.frost.com/), the international

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Volume 22 . Number 3 . 2002 . 206–214

marketing consulting company, underlines

the durability of the recovery in advanced

motion control product sales. Amassing

sales worth $1.43 billion in 2001, the market

is forecast to reach revenues worth $1.82

billion in 2008. This advance should be

supported by declining prices and the

potential for enhanced productivity, driving

penetration of advanced motion control

products into a broadening spectrum of

industrial sectors.

‘‘Falling prices have helped increase the

viability of advanced motion control products

in comparison to cheaper electromechanical

alternatives based on pneumatic and

hydraulic technologies. The decrease in prices

has positively influenced demand with the

resultant volume growth expected to outstrip

price reductions, thereby supporting revenue

growth’’, reports Mik Sabiers, research

manager at Frost & Sullivan.

A major factor in the expansion of advanced

motion control systems has been its potential

for enhanced productivity. A growing

emphasis on improved productivity and cost

reduction in manufacturing processes is

building a trend towards the automation of

production. With end-users increasingly

prepared to pay for electrically automated

motion control systems so as to eliminate

labour costs and maintain competitiveness,

the demand for advanced motion control

systems is expected to grow.

Market expansion is also likely to be

driven by end-users in industries such as

packaging, pharmaceuticals and food

processing that have traditionally utilised

electromechanical motion control systems.

These sectors are becoming increasingly

receptive to the use of advanced motion

control products. Another area gaining

importance is the military market, where

increased defence expenditure is likely to

spur growth. Rising demand from other high

growth potential industries is also

anticipated to further the market for

advanced motion control products.

The widening use of advanced motion

control in these new markets is expected to

offset the increasing saturation of demand in

the key industrial automation sector, in

particular the machine tools segment. As Mr

Sabiers notes, all companies can benefit

from an awareness of growth patterns in

other application areas, particularly faster

growing niche markets that are less likely to

attract the attention of major suppliers in the

near future.

‘‘More peripheral markets, and particularly

the printing sector and processing industries,

remain unsaturated and offer strong potential

for future growth’’, he adds.

Technological developments are further

expected to aid revenue growth. The

increasing use of PC-based controllers, and

more particularly, intelligent drives, is

expected to contribute to growth in the

advanced motion control market.

Technological changes are likely, however,

to have a negative impact on some product

segments. For example, the shift to intelligent

drives and the more widespread use of

PC-based controls are expected to gradually

reduce the need for controllers. This, in turn,

is likely to lead to a substantial moderation in

the future growth potential of the controllers

market.

While servo motors, servo drives and

feedback devices are expected to account for

a rising proportion of these revenues,

stepper motors, stepper drives and

controllers are expected to diminish in

relative significance.

With competition intensifying, the

competitive landscape is displaying less

fragmentation. The market is currently

going through a spate of consolidations,

mergers, and acquisitions. This trend is a

reflection of end-users demanding complete

motion control systems and favouring

multinational suppliers with wide product

ranges and international support networks.

Changing end-user requirements,

combined with price reductions and the need

to achieve scale in manufacturing, are

increasingly tipping the balance in favour of

larger suppliers, as can be seen from the

dominant presence of leading multinational

competitors, such as Siemens, GE Fanuc,

BoschRexroth (Indramat), Rockwell

Automation and Danaher, that together

account for over one third of revenues in the

market.

In total terms, the European market for

advanced motion control, which suffered a

reversal due to the uncertain economic

climate, is starting to show the signs of robust

recovery. Its increasingly visible presence in

newly emerging applications is certain to

presage a return to the boom days of the past,

the study concludes. http://frost.com

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Volume 22 . Number 3 . 2002 . 206–214

NanoMuscle selects ASE for theproduction of NanoMuscle actuators tomeet increasing demand

Keyword Actuators

NanoMuscle Inc., a developer and

manufacturer of advanced miniature motion

technologies, today announced that

Advanced Semiconductor Engineering, Inc.,

one of the world’s largest semiconductor

packaging and testing companies, has been

selected to provide manufacturing services

for NanoMuscle’s linear actuator products.

The expanded production at ASE’s Korea

facility will allow NanoMuscle to sufficiently

meet the increasing demand for their

products.

‘‘With growing demand from our

customer base across a wide range of

industries such as automotive, consumer

electronics, computer peripherals,

children’s toys and medical instruments, we

needed to quickly ramp-up on production

and sought a partner who could provide

services on a turnkey basis’’, said Rod

MacGregor, CEO of NanoMuscle. ‘‘ASE’s

Korea facility is capable of producing

millions of high quality actuators for us each

month and delivering them to our customers

around the world.’’

‘‘Due to the many applications of small

motors, we foresee that the market potential

for these products will burgeon in the next

few years’’, said Jim Stilson, president of ASE

Korea. ‘‘ASE’s Korea facility possesses

immense experience in IC packaging and has

the additional expertise in module assembly.

Hence, we were able to adopt our existing

manufacturing processes for NanoMuscle

actuators based on their innovative

technology.’’

NanoMuscle actuators enable a new

generation of devices by providing silent,

miniature motion. At one-tenth the size and

one-twentieth the cost, NanoMuscle’s

actuators displace traditional small motors and

solenoids in automotive, consumer electronics,

computer peripherals, children’s toys and

medical instruments, enabling a new

generation of micro devices by providing

affordable miniature motion. The NanoMuscle

actuator uses a breakthrough process to

harness the power of shape memory alloys

(SMA). While traditional small motors and

solenoids can be bulky, expensive, and noisy,

the NanoMuscle actuator is completely silent,

smaller, lighter and less expensive than

comparably priced solutions.

For more information, please go to

www.NanoMuscle.com

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Volume 22 . Number 3 . 2002 . 206–214

Delphi expands dieselinjector output usingautomated assembly

John Mortimer

Delphi Diesel Systems is investing $60

million over two years at its plant in

Stonehouse, Gloucester, UK, aiming to treble

output of fuel injection equipment for diesel

engines – both electronic unit injectors

(EUIs) and electronic unit pumps (EUPs) –

over the next five years.

Plans call for the company to raise installed

capacity from 400,000 truck diesel injection

systems to over one million units by 2003. In

addition, the company will maintain its

current installed annual capacity of 400,000

passenger car fuel injection systems.

David Friday, director and general manager

of Delphi’s heavy-duty business, based in

Stonehouse, explained: ‘‘I expect the growth

of business over the next five years to more

than treble’’, he said. ‘‘It might even

quadruple.’’

Significantly, Friday has no plans to

increase the present manufacturing floor area

at Stonehouse, even though land is available.

Indeed, Friday takes great pride in the role

played by the company’s lean manufacturing

teams in their efforts to generate more output

from a given floor area.

‘‘We are producing three times as many

items as we were four years ago, but with

fewer people’’, declared Friday, who also

expects further increased output to be

achieved with ‘‘only a few more people’’ as the

company ‘‘leans’’ further its manufacturing

processes.

It was in 1992 that production of EUIs

began at Stonehouse, then a brand new,

tailor-made facility built by Lucas Diesel

Systems to produce this specialized

high-value component in high volumes. The

diesel fuel injection business then was owned

by Lucas Industries Ltd. In 1996 Lucas

Industries merged with Varity of the USA to

form Lucas Varity before, three years later, in

1999, being acquired by TRW. On

10 January 2000, Lucas Diesel Systems was

purchased by Delphi Automotive systems. By

merging its own diesel activities, Lucas Diesel

Systems overnight became the second largest

diesel fuel injection business in the world.

In year 2000 Delphi Automotive Systems

recorded annual sales of $29.1 billion for its

world-wide businesses that provide world-

class components for the automotive industry.

Delphi Automotive Systems itself began life in

1995, being spun out of the General Motors

subsidiary, ACG Worldwide (Automotive

The author

John Mortimer is a freelance manufacturing and

engineering journalist based in Milton Keynes, UK and an

Associate Editor of Assembly Automation.

Keywords

Engines, Fuel economy, Testing, Assembly, Robots

Abstract

A manufacturing plant for the manufacture of diesel fuel

injection equipment at Stonehouse, Gloucester, UK is

being expanded at a cost of $60 million to cater for a new

production using lean manufacture and without

expanding the manufacturing area.

Electronic access




available at


Feature

215

Assembly Automation

Volume 22 . Number 3 . 2002 . pp. 215–222


DOI 10.1108/01445150210436400

Components Group Worldwide). It became a

totally independent company in 1999.

Delphi Automotive Systems employs a total

of 202,700. Its main competitors are Bosch

(annual sales of $20.6 billion), Visteon ($19.5

billion) and Denso ($16.4 billion). Delphi

Diesel Systems is part of Delphi Energy and

Chassis Systems – itself an $11.6 billion

business with 51,000 employees world-wide.

In the diesel engine business, the

established practice for many years was first to

use inline pumps and then rotary pumps to

create the high pressures necessary for

injection of diesel fuel into engine combustion

chambers. Since these early designs, many of

which are still in use today, there has been a

watershed in diesel fuel pump and injector

design, spurred on by the need to achieve

emissions legislative regulations, improve fuel

economy and pave the way for lowest cost

after-treatment. This watershed was made

possible by the increased availability of

advanced electronics and new trends in

miniaturization.

Leading the field

Lucas Diesel Systems has led the way with

electronically-controlled EUIs driven by the

engine camshaft; but new concepts are

emerging including piezo and digital valve

systems.

Lucas Diesel Systems was the first to move

EUIs into production in 1988. The first

application in 1992 was in Caterpillar’s 3176

diesel engine – the first Caterpillar diesel

engine to be designed specifically for

on-highway application. This advanced

engine used a weight-saving aluminium

spacer deck and articulated pistons. The

second application was as a heavy-duty unit

fitted to the new Volvo D12 engine in 1993.

In 1997 the first EUI for car and light

commercial vehicles was in the Land Rover

‘‘Storm’’ engine. In 2001, the business also

launched its own light-duty common rail fuel

injections system.

But the EUI is not a new development. It

had been evolving within Lucas Diesel

Systems over a number of years, at least since

1980. The system first emerged as a

‘‘colenoid’’ – a very powerful solenoid.

Engineers learnt a great deal from this

technology; indeed their experience led to a

more compact and lower cost design.

Engineers became increasingly aware that if

they placed the valve near to the pumping

chamber they could reduce internal volumes.

This in turn reduced the size of the pump and

subsequently the size of the solenoid. Some

four or so years ago it was found the solenoid

could be packaged within the body itself – the

basis of the current E1 and E3 designs of

EUIs. An earlier A3 design has the solenoid

mounted outside the main valve body (see

Figure 1).

There were plans also some years ago to

create a compact EUI design for use in

Volkswagen’s passenger car diesels, but the

decision was taken at a senior level within the

French headquarters of Lucas Diesel Systems

not to pursue that development but instead to

concentrate on common rail systems.

In addition to the A3, E1 and E3 designs,

Delphi engineers have developed EUPs based

on E1 and E3 technology. These are linked to

‘‘smart’’ injectors through engine controllers

using sensors (see Figure 2). The EUPs will

follow the E3 units into production.

Production of E3 is due to begin in 2003.

‘‘In the first phase of our reorganization we

are closing up manufacturing space in several

areas as well as achieving gains in productivity

to make space available for E3 production’’,

said Friday. ‘‘We will also use better tools and

techniques.’’

Space will also be made available for the

manufacture of EUPs, once production of

E3s has settled down.

The Stonehouse plant is now the only

source of EUIs world-wide within the Delphi

business. The heavy-duty business unit itself

employs 470 people (at Stonehouse 360) and

the design and development unit at Park

Royal, London. The present installed

capacity is 500,000 units a year – 400,000

units for car and LCV application and

100,000 units for heavy trucks.

According to Friday, the heavy-duty group

with its resources offers:. Best product technology to meet

emissions with good fuel economy.. Best machines tools and lean approach to

give good quality, minimum investment,

good flexibility and good value for

money.. Ability to take out cost year-on-year.. Best team with up-to-date skills,

flexibility and adaptability that can be

enthusiastic, ever improving and proud of

its achievements.

216

Delphi expands diesel injector output using automated assembly

John Mortimer

Assembly Automation

Volume 22 . Number 3 . 2002 . 215–222

. Good understanding of market structure,

customer requirements and competitive

activity.. Excellent teamwork, communication and

training.. Management with vision, determination,

confidence and prepared to take bold

actions and decisions.

The year 2001 saw the start of a new ‘‘change

programme’’ with lean manufacturing and

lean enterprise being the focus of attention at

Stonehouse, together with the adoption of

lean enterprise also at Park Royal.

Various types

The Stonehouse facility produces three types

of diesel fuel injector but plans call for a

fourth type – the EUP.

Figure 1 Delphi’s electronic unit injectors (EUIs) have matured from a side-mounted spill valve (A3) through to in-

line single (E1) and two-valve (E3) configurations.

Figure 2 Fig. 2 Delphi’s electronic unit pumps (EUPs) are capable of meeting Euro 3 and Euro 4 emissions

requirements. They use ’‘smart’’ injectors

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John Mortimer

Assembly Automation

Volume 22 . Number 3 . 2002 . 215–222

When the current phase of facility

reorganisation is complete the plant will be

making EUI units for Land Rover’s

five-cylinder Storm engine (this EUI is now

regarded as a one-off design even though

there is a manufacturing line that is

specifically dedicated to it); the EUI 200 (or

the A3) for the John Deere 12 litre engine and

the Hyundai L-engine or Powertec 12 litre

power units, the single-valve E1 injector for

Volvo and the new two-valve E3 injector, also

for Volvo.

Volvo was keen to be the first to use the new

E3, giving it an element of exclusivity and a

lead over its competitors. Production of the

E3 is now being ramped up in readiness for

volume production to begin in 2003. E3 also

uses a ‘‘smart’’ injector, the control of which is

monitored by the engine controller. The E1

and E3 for Volvo will continue for a time in

parallel before E1 finally eases out.

Next to come on stream will be the EUP,

which also has a peak injection capability of

2,000 bar (like E1 and E3). This is suitable

for cam-in-block truck diesel engines of 1.5 to

2 litres per cylinder. It can also give higher

injection pressures than the single valve

system and common rail systems.

Production of EUPs, for an as yet unnamed

customer, could begin in 2003 or early 2004.

The A3, E1 and E3 designs are all of

cam-in-head configuration; that is, the

camshaft is mounted in the cylinder head.

At present, Volvo is the principal customer

for the company’s E1 as well as for the next

generation E3, due to come on stream in

2003. However, Friday hints that there could

be four new customers in addition to the

present customer base of Volvo, John Deere,

Hyundai and Land Rover.

The $60 million investment is being spread

over the current year and next year and is

being used to reorganize existing equipment

and install new capital equipment to

manufacture the E3 injectors and the entirely

new EUP design.

The latest designs of Delphi EUIs are

compact and a far cry from the chunky

features of the original designs for Caterpillar

and Volvo.

‘‘Ten years ago we did not have the

technology available to miniaturize the

design’’, notes Friday. ‘‘The design has

evolved from the external solenoid

configuration to the in-line single valve design

and then on to the two-valve configuration of

E3’’ – and the EUP?

‘‘We have taken the technology of the EI

and the E3 and applied it to create the EUP’’,

said Friday. ‘‘The technology has moved on in

other areas, most notably in terms of both

pressures and speeds.’’

The net effect is that, to achieve high

delivery pressures, very close tolerances are

demanded of components that fit together.

This implies a high degree of precision as well

as a strong element of automated

manufacture.

World-wide business

Delphi Diesel Systems is part of Delphi

Automotive Systems; it has world-wide sales

of $1 billion from 8,000 employees in 13

manufacturing operations and three principal

engineering centres. It supplies nine of the

world’s top ten diesel engine makers.

The heavy-duty element of the business is

responsible for all aspects of the EUI and

EUP business, including design, development

and manufacture. It employs 360 people at

Stonehouse in manufacturing and 115 at Park

Royal, London, in design and development.

Current annual sales of the heavy-duty

business are ‘‘between $75 million and $150

million’’, according to Friday.

There are no plans to increase the present

manufacturing area. Indeed, Friday takes

great pride in the role played by the

company’s lean manufacturing teams in

generating more output from the same floor

area.

‘‘We are producing three times as many

items as we were four years ago, but with

fewer people’’, declared Friday, who notes

that he expects further increased output to be

achieved with ‘‘only a few more people’’ as the

company leans further its manufacturing

processes.

When the next phase of facility

reorganization is complete the plant will be

making the EUI units for the Land Rover

Storm engine, the EUI 200 (A3) for the 12

litre John Deere and 12 litre Hyundai power

units, the single-valve E1 injector for Volvo

and the new two-valve E3 injector, also for

Volvo. The latest two-valve configuration

offers higher operating pressures (typically

2,000 bar at engine speeds of 1,800rpm,

compared with about 1,800 bar for a

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John Mortimer

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Volume 22 . Number 3 . 2002 . 215–222

single-valve system. Typical operating

pressure for common rail is in the region of

1,500 bar.

Volvo was keen to be the first to use the new

E3, giving it a lead over its competitors. E3

also uses a ‘‘smart’’ injector, the control of

which is monitored by the engine controller.

The E3 has an application range of 1.5 to 2.6

litres per cylinder.

Next to come on stream will be the EUP,

which also has a peak injection capability of

2,000 bar (like E1 and E3). This is suitable

for cam-in-block truck diesel engines of 1.5 to

2 litres per cylinder. It can also give higher

injection pressures than single valve system

and common rail designs. It also makes use of

technology and components that form part of

E1 and E3.

In fact, Delphi has been quietly marketing

the EUP system within the diesel engine

industry around for years. It is effectively a

version of the E1 system. The latest EUP is a

second-generation device with a solenoid at

the injector as well as one by the pump.

The EUP is designed for diesel engines with

injection camshaft drive systems mounted on

the side of the cylinder block; as such they

known as cam-in-block designs. In general,

they are cheaper than the cam-in-head unit

injection systems. Daf Trucks (with its UPEC

design) in particular uses cam-in-block fuel

injection. It is understood that Delphi does

have a customer for its new EUP system.

Meanwhile, Delphi’s A3, E1 and E3

designs are all of the camshaft-in-head

configuration.

According to Friday, cam-driven systems,

like E1/E3 and EUP, ‘‘will outperform

current common rail solutions’’.

‘‘I do not believe common rail is the best

heavy-duty solution for Euro 1V’’, said

Friday, ‘‘nd while some third-generation

higher pressure common rail solutions will

become apparent for Euro V, most will not

emerge until much later’’.’

Lean manufacture

Manufacture of EUIs and EUPs is a highly

precise, heavily capital intensive activity.

Most, if not all, the components are

cylindrical, lending themselves to CNC

machine tools. The manufacturing area itself

is broken down into about a dozen cells.

The entire manufacturing area is

self-contained with various cells including its

own prototyping unit; the automated Land

Rover spill valve manufacturing unit; a

supermarket type store with tug delivery to

line-side; a test area; fully automated build

and test area for Land Rover Storm injectors;

cleanliness checking-off cells; standards room

and high pressure measuring room with print-

off; an actuator and solenoid manufacturing

unit complete with coil winding, terminal

insertion, welding, full testing between

stations, and injection moulding of the unit

onto the stator; full testing between stations;

complete system test cells and cleanliness

checking-off cells.

Other cells within the facility handle: A3

body soft machining; E1 body soft machining;

A3 match grinding of plunger-to-body

stations; four-stage honing on a Kadia

machine; hard turning of E1 valve bodies, and

match and lift grinding of E1 valve using chip

on pallet to capture data.

As part of the process of continuous

improvement and lean manufacture, steps are

being taken to move the A3 and E3 cells

closer to the testing area. These will be new

lean A3 and E1 assembly cells.

Manufacturing engineers are also making

space for the new EUP assembly and test

processes.

One of the largest cells at Stonehouse is

devoted to the manufacture of spill valves for

Land Rover’s Storm engine EUIs. As

mentioned, this is a fully automated assembly

and test line (with Ewab conveyors) making

full use of match grinding. The line is

replenished every two hours.

Match grinding allows Delphi to achieve

exceptionally tight tolerances between pin

and the guide bores. In-line quality systems

ensure that every pin is within the specified

1mm tolerance as well as allowing 100 per cent

statistical process control in real-time (see

Plate 1).

The cell runs on two shifts using six people

and has a capacity of 9,000 units a week.

Typical output at present is in the region of

6,000 a week. The engine is fitted to Land

Rover Defender and Discovery.

In this particular cell there is one R/F tag

per pallet and each pallet carries one

component.

The Stonehouse facility uses the Delphi

manufacturing system. This makes

considerable use of Japanese poka-yoke

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(Japanese for error-proofing not fool-

proofing, as is sometimes suggested – industry

does not employ fools) techniques to ensure

that key processes have been completed

within the required tolerances. For example,

at one EUI spill valve manufacturing station,

a strain gauge in the insertion mechanism

automatically checks that the pin insertion

force is correct. The pin must fit into the

guide with a tolerance of 1.5mm (see Plate 2).

According to Friday, poka-yoke is used in

almost every aspect of EUI manufacture.

‘‘It will continue to be so, but especially in

respect of sensors and vision systems. For

example, sensors detect holes using light

beams, while vision systems can look for

burrs’’, he added.

Vision systems

Vision systems are used in the plant to check

that the correct product is being built. It is

estimated there could be at least 20 camera-

type systems in operation together with other

systems that can recognize colour.

For example, in the Land Rover facility

engineers use vision systems to check the tip

of the nozzle, to check for either four or five

nozzle holes, the length of a spacer and the

colour of a particular bush.

Vision systems will be used ‘‘much more’’

on the manufacture of the E3 units for Volvo

to check again for variety, but this time much

earlier in the line, to check the existence of

key features. They will also be used in EUP

manufacture.

‘‘This will be particularly valuable when we

are doing more automated assembly’’, noted

Friday.

Engineers use a variety of pick-and-place

robots with almost all the hard stage

machines employing this type of robot to

pick-and-place components from pallets. In

some cases there is manual pallet movement

between stations.

‘‘In the future we will use more intelligent

pick-and-place devices’’, declared Friday.

‘‘For example, we will use robots to deburr

during unloading, or to insert a dowel

during load or unload. At the same time we

will be checking the unit with a vision

system.’’

The Stonehouse facility has long

experience of working with DT Industries

in the design and build of automatic

assembly and test stations. The business

was formerly Lucas Assembly and Test Ltd,

in Buckingham.

‘‘We shall continue to do so if their

products remain state-of-the art and

competitive’’, said Friday.

In the Land Rover Storm engine cell, parts

movement is handled by means of intelligent

chips mounted on pallets. Radio frequency

tagging (RF) is used. In this particular cell

there is one RF tag per pallet and each pallet

carries one component. This is in contrast to

the E1 valve line where the tag on a pallet of

36 parts stores the match grind and lift grind

dimensions of each part individually by

location to avoid the need to use shims. The

same system is used to store information

about each assembly and test operation on

E1, much of which is then laser etched onto

Plate 1 Match grinding allows Delphi to achieve tight tolerances

between the pin and the bore of EUIs that it supplies to land Rover

Plate 2 The Delphi manufacturing system uses poka-yoke techniques to

ensure key processes are completed within required tolerances

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Assembly Automation

Volume 22 . Number 3 . 2002 . 215–222

the data matrix of each injector, thus making

each injector individually matched to the

engine (see Plate 3). It will be used on E3

and EUP lines also.

The Delphi manufacturing system was used

also to optimize the assembly of EUIs at

Stonehouse. Just two people are required to

operate the E1 assembly cell using a high level

of automation to ensure consistency and to

allow the integration of extensive in-line

quality checking (see Plate 4).

The E3 cell, when it comes on stream, is

likely to be manned by three operators.

Delphi engineers have developed the line’s

concept, with its many stations, but detail

design and manufacture is in the hands of

three suppliers.

Meanwhile, the new EUP assembly cell is

likely to use more automation, especially in

the movement of components from one

automatic station to another. This is

because the pump body is at least twice the

weight of the E3 unit and it is also much

larger.

Meanwhile, prior to assembly, racks of A3,

and E1 (later E3 and EUP) bodies and

plungers undergo ultrasonic washing to

ensure reliability and accuracy when running

at the very high operating pressures

encountered during normal service. It is

essential that all debris is eliminated at this

stage (see Plate 5). When the time comes,

EUP components will be ultrasonically

washed also.

Once completed, all A3, E1 (and E3 when

ready) units undergo a thorough functional

test in a system designed and built by Delphi

engineers. Delphi engineers also wrote the

software. Eighteen parameters are measured

including fuel delivery, injection pressure,

valve lift and timing, as well as various

temperatures (see Plate 6). A similar

functional test will be used for the upcoming

EUPs.

Finally, after assembly, the RF tag is read

and manufacturing and performance data are

downloaded to the facility’s archiving system.

Plate 3 During assembly of EUIs a radio frequency tag carries size and

tolerance data for each of the 36 valves on the pallet

Plate 4 Two people are required to operate a cell for the assembly of

EUIs. The cell uses a high level of automation

Plate 5 Racks of bodies and plungers for Delphi’s E1 EUI injector receive

ultrasonic washing to ensure accuracy and reliability

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Selected data are then laser etched onto each

unit injector with the mark tested to ensure

that all of the data can be read accurately.

At the customer’s factory, the laser mark is

read again and data downloaded to the engine

control unit, allowing it to optimize control

signals to match the characteristics of each

individual injector. The system provides a

greater level of control than is possible with

traditional systems that batch injectors into

performance bands (see Plate 7).

Plate 6 Completed E1 EUIs undergo a thorough functional test in a

system designed by Delphi Diesel SystemsPlate 7 Following assembly of the EUI, the RF tag is read and

manufacturing and performance data are downloaded to the archiving

system

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A new wave ofsynchronous robots

Anna Kochan

One robot is good but two are even better.

This was the main theme running through

Paris’ Euro-Assemblage Exhibition this year.

Use one robot for holding a workpiece and

another for working on it and the result is an

automated solution that excels in flexibility

potential. Many companies at the French

show feature their capability to perform such

an exploit.

Fanuc is the leader in this domain with its

dual-arc concept. At the exhibition, it

demonstrated the arc welding application for

exhaust systems that Renault is implementing

in its assembly plants. This involves two

robots, one for manipulating the assembly

and one for welding it, with a two-camera

vision system to ensure an accurate result.

Christian Guibert, manager director of Fanuc

Robotics France, claims to be handling

customer enquiries for some 100 new

synchronous robot projects.

At the Paris show, Commercy, the French

systems integrator that partners with Fanuc

for robot welding projects, also exhibited the

dual-arc concept for the welding of exhaust

systems, as well as new configurations of

welding cells. One configuration, specially

designed for the latest design of exhaust

systems for diesel engines, mounts the

welding robot on an inclined turntable (see

Plate 1). ‘‘These exhaust systems are

complex. They incorporate catalytic

converters and particle filters. Using this

configuration combined with inclined

fixturing for the exhaust components, it is

possible to orientate the welding robot relative

to the workpiece in the optimum position for

a quality weld and to complete the entire

welding cycle at a single station. It would

otherwise require several stations’’, explained

Remi Marchal, sales engineer at Commercy.

Faurecia, the French automotive supplier,

installed four of these cells in 2001 for the

welding of diesel engine exhaust systems.

Also new on the Commercy stand was the

linking of an arc welding robot with a vision

system for seam finding and seam following.

The vision system employed is from

Canadian company Servo Robot, even

though Fanuc offers its own vision system.

‘‘The Servo Robot system is less expensive

than the Fanuc one’’, adds Remi Marchal.

Like Fanuc and Commercy, Motoman also

demonstrated exhaust system welding at the

Paris show. The Yaskawa subsidiary, based in

Sweden, proposes a solution based on three

The author

Anna Kochan is European Associate Editor for Assembly

Automation.

Keywords

Assembly, Robotics, Parts, Machine vision, Welding,

Automotive components industry

Abstract

Reports from the Euro Assemblage Exhibition, in Paris,

highlights the development of synchronous robots,

identifies new approaches to robot control and

programming, outlines the application of

six-axis robots to parts feeding.

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DOI 10.1108/01445150210436419

robots all welding the same assembly

simultaneously. With 27 axes, the Motoman

controller is capable of managing the

movement of the robots and of the

manipulator that is holding the assembly. It is

a solution that is already running in industry,

says Jean Paul Clerc, managing director of

Motoman Robotics France.

Synchronous robots was also featured on the

stand of systems integrator Bema where Fanuc

robot and ABB robot worked together on a

welding application (see Plate 2). Here,

however, the innovation was not particularly in

the fact that robots from different

manufacturers were working synchronously.

The most original feature of the demonstration

was the complete elimination of pneumatic

systems and their replacement by electrically

driven devices. ‘‘Compressed air is expensive,

dirty and complicated. In addition, its energy

efficiency is only 10 per cent. Another

limitation is that only on/off control is

possible’’, explains Yves Ravot, Bema CEO.

He says that the all-electric robot welding/

handling cell will not only be less costly to run,

but it will also give improved accuracy. The

range of all-electric devices now available from

Bema includes a wide variety of electric

grippers and clamps, connectors and fixturing

units.

Other exhibitors at Paris highlighted

developments in control systems and man-

machine interfaces. Adept, for example,

showed its new SC robot controller and its

new desktop man-machine interface.

The SC controller, which will replace the

current MV controller when it becomes

available later this year, incorporates

innovative Firewire technology. ‘‘This high

speed communications system was originally

developed by Apple and Sony for video

camera applications and we are the first of the

robot companies to use the technology’’,

claims Aldo Arban, director of Adept

Technology France. It is technology that

enables a data transfer rate of 800Mb/sec. to

be achieved. As a result, the cabling of a

robotic cell is greatly simplified. Instead of

each element of the cell requiring a direct

cable connection into the controller, all the

cell components can now connect to the

controller via a single cable. The simplification

of design that is possible leads to a controller

that is less than half the size of the MV and

costs 40-50 per cent less.

The desktop product that Adept showed for

the first time at the Paris event is a software

package that is designed to provide a

graphical programming, controlling and

monitoring interface to Adept equipment

using V+ or MicroV+. It is much more user-

friendly than the previous interface, says Aldo

Arban.

At the show, Adept also demonstrated a

first-time linkup of one of its six-axis robots

with the FlexFeeder device. While Adept’s

vision-assisted FlexFeeder is widely used in

conjunction with Adept Scara robots for

picking up randomly-arriving parts from a

conveyor, the six-axis robots from Adept are

only recently available on the market – and

they add greater functionality to the

FlexFeeder concept. ‘‘Using a Scara limits the

application to parts and applications where a

vertical pick and place action is acceptable,

the robot always working in a downwards

direction. With a six-axis robot, the parts can

Plate 1 Specially designed for the latest design of exhaust systems for

diesel engines, the welding robot is mounted on an inclined turntable

Plate 2 The most original feature of Bema’s synchronised robot

demonstration was the complete elimination of pneumatic systems and

their replacement by electrically driven devices

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A new wave of synchronous robots

Anna Kochan

Assembly Automation

Volume 22 . Number 3 . 2002 . 223–225

be picked from any angle and placed at any

angle, in an upwards or downwards

direction’’, Aldo Arban explains. This will

greatly extend the field of applications for the

FlexFeeder, he adds.

Like Adept, the French robot maker Staubli

is also developing new controls and man-

machine interfaces. At the Paris show, Staubli

previewed the new CS8 control system. Using

a new operation system and the new

generation programming language VAL3, the

CS8 is an entry-point product designed for

simple applications such as handling and

assembly. It is a 100 per cent Staubli product

and it is Staubli’s first PC-based controller,

claims Jean-Luc Bordas, technical sales

manager. Previously, the controls were

VME-based and used Adept’s V+ as the

programming language. Jean-Luc Bordas

believes that having developed the control

electronics and the programming language so

that they work well together, Staubli has

achieved a system that enables robot

applications to be programmed and

implemented simply and quickly.

Staubli also exhibited the V_Cell man-

machine interface. Although it was

introduced two years ago, sales of V_Cell only

started in June 2001. Now, says Jen-Luc

Bordas, customers ask for it systematically.

‘‘Instead of having to develop their own

interfaces, customers can buy V_Cell,

customise it to their own needs and use it as a

common interface for all their applications. It

reduces programming time by 40-50 per

cent’’, he claims.

225

A new wave of synchronous robots

Anna Kochan

Assembly Automation

Volume 22 . Number 3 . 2002 . 223–225

US NationalManufacturing Week

Dick Bloss

The National Manufacturing Week show, in

Chicago, proved the perfect venue for

Assembly Automation to explore the current

situation in the market for automated

assembly and to preview the latest in new

products and services. Top executives at

major automated assembly industry suppliers

were interviewed regarding the state of the

market and their plans and strategies for

coming out ahead of the pack as the North

American market returns to its former glory.

Deloitte & Touche, a major accounting

firm, indicated that the manufacturing section

of the US economy, which had been on a

downward spiral, had experienced a

1.6 percent increase in new factory orders in

January. Doug Engel, national managing

director for the firm said: ‘‘We have seen

organizations employing strategic flexibility’’

in response to current conditions.

Ted Zajac Jr, president of Zaytran, a

supplier of specialty grippers, indicated that

he felt he had seen less of a decline than most

competitors because of his focus on special

applications, larger capacity grippers and

some successful design wins in North

American and international auto production

plants. He also said his cooperation

agreement with the major Japanese full line

automation accessories giant, SMC, had

opened new doors at just the time many other

segments were in a down turn.

Montech marketing manager Corinne

Martin said that the European producer of

assembly actuators and transport units was

starting to see a rebound in business. She felt

the market was coming out of the flat at the

bottom.

Paul Schnizler, formerly president of

Industrial Profile Systems (IPS), supplier of

modular structure elements, who is now

business unit manager for IPS at Parker

Hannifin, said many of the segments IPS

serves and ongoing projects held up fairly well

and it was mainly newer projects which were

seriously depressed in the past year or so. He

sees the demand picking up. IPS, with about

US$20 million in turnover, was acquired

recently by Parker Hannifin.

A Festo representative, Mark Stankiewicz,

said Festo has enjoyed good demand from the

paper industry segment, which moderated

their turnover decline. Festo anticipates a

major pickup in the semiconductor industry

in the next 6-12 months. To address this

anticipated surge, Festo has established a

The author

Dick Bloss is an Associate Editor for Assembly

Automation.

Keywords

Assembly, Marketing

Abstract

A report from the 2002 National Manufacturing Week

Exhibition, combining executive interviews on the outlook

for the current market for assembly in North America plus

new product and services introductions from Schunk,

Festo, Thomson, PHD, GE Fanuc, NB, Rexroth Bosch,

Bimba, THK, Bayside and Techno.

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DOI 10.1108/01445150210436428

facility on the West Coast to better serve the

semiconductor and clean room industry with

engineering support and product for custom

applications. Festo is a major German

producer of pneumatic and electronic

components, controllers and engineered

systems.

Schunk Inc., an international provider of

precision automation, workholding and

toolholding solutions, says its answer to

market conditions is best represented by its

recently expanded North American facility in

North Carolina. The 35,000sq. ft of office,

engineering, manufacturing and warehouse is

better able to meet the needs of customers.

Five CAD design seats provide for quick

customization of holding solutions. A multi-

million dollar inventory of products and

replacement parts insures speedy delivery.

Emil Melvin, national sales manager for

Del-Tron Precision, Inc., supplier of slides

and stages, reported that his firm is

experiencing a slight uptick in sales. NKS, a

supplier of motion control devices, indicated

that it is starting to see the semiconductor

market come alive a bit. ATI, a supplier of

robotic tool changers, crash protectors and

torque sensors reported business as flat, with

new project opportunities very soft.

President of another modular structural

elements supplier expressed the feeling that

he had seen the bottom and that a slight

uptick was underway. He felt the downturn

had come to his firm later than for some. The

marketing manager of a major supplier of

grippers and actuator slides was gloomy that

the light at the end of the tunnel had not been

turned on yet.

Overall, the industry is not discouraged and

announced a bevy of new product and service

offerings.

Festo introduced the new pre-engineered

HAT, two- and three-axis pneumatic systems

for cantilever, Cartesian and gantry-style pick

and place applications (Plate 1). The Festo

HAT system offers pre-engineered modules

which can be quickly configured, reducing

design and engineering time, providing

excellent performance and at lower prices

than custom motorized or other pneumatic

systems. Travel options range from 50mm to

500mm and with load capacity to 5kg.

To meet the needs of faster machine cycle

times, Festo introduced the MH2 miniature,

fast switching pneumatic valve, offering flow

rates to 100 litre per minute and extremely

fast switching rates to as low as 2-6

miliseconds. Special design features allow the

MH2 valve to be easily retrofitted into

existing applications to allow them to benefit

from the faster switching times.

MicroStage 46, a new high performance,

low cost linear motion slide from Thomson

Industries (Plate 2), features aluminum

design for optimum strength, rigidity, light

weight and lower cost than heavier steel based

products. A patented bearing segment design

provides backlash free assembly without

sacrificing load capacity or smoothness of

operation. The new slide stage is available in

stroke lengths to 1,840mm. Applications for

the MicroStage 46 include multi-axis pick

and place, component insertion for PC board

assembly, and wafer transport and handling.

A rotary actuator with a hollow pinion is a

featured new product from PHD, Inc. Their

new series RLxH rotary actuators in bore sizes

of 25mm, 32mm and 50mm and torque

ranges of 3.6Nm to 46.8Nm at 6 bar, features

a hollow pinion for protection and routing of

electrical cables and air lines. The actuators

provide up to 180 degrees of rotation and

Plate 2 Thomson Industries MicroStage 46 linear slide

Plate 1 Festo three-axis pneumatic pick and place robot

227

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Dick Bloss

Assembly Automation

Volume 22 . Number 3 . 2002 . 226–229

optional shock absorbers for quiet operation

and end of rotation deceleration.

PHD, Inc also introduced a PS reach and

pick device (Plate 3) which combines a

pneumatic powered slide and a pick clamp

which are activated by a single external

control valve. The jaws stay open until the

slide reaches its fully extended position.

Clamps, which may be rotated and spherically

adjusted to suit application, remain closed

even is air pressure is lost.

GE Fanuc introduced their new Global

Solutions services. GE Fanuc can assist client

companies with implementation of the

Cimplicity# Collaborative Production

Management Suite of software. The suite can

aggregate, deliver and facilitate dynamic

business decision making within the entire

manufacturing environment. GE Fanuc also

announced the first major contract for this

Global Solutions Division with Ford Motor

Company. The new solution for Ford will

automate the production scheduling, routing

and tracking of the assembly of vehicles at

plants around the globe.

Also introduced by GE Fanuc was the new

18i MB5 CNC controller. A first in that the

controller can take a five-axis part program

post processed for one configuration of five-

axis machining center and without further

post processing run the same part on a

different configuration of the five-axis

machine.

This will prove a major benefit to machine

shops with several configurations of five axis

machines. They will not have to maintain

several part programs files to insure a part can

be run on the first available five-axis machine.

NB Corporation of America introduced a

new line of smaller all metal linear slides

designed especially for clean room

applications such as semiconductor or

medical device production. The units feature

repeatability to 2 micron. A retained ball

design makes for easy of maintenance. NB

features an uncommonly quick delivery lead

time of three weeks or less on most products.

Rexroth Bosch introduced the VarioFlow2

(Plate 4) single strand chain conveyor. The

VarioFlow is available in two widths, 65mm

and 90mm and offers transport speed to

50m/min. The single strand enables assembly

functions such as part feeding and packaging

to occur on either side of the moving conveyor

system. The STAR linear motion slide, just

introduced, features a toothed belt drive

offering speeds to 5m per second. The motion

is guided by four linear bushings that run on

two hardened steel shafts for significant

load-carrying capacity and long service life.

To reduce installation cost and maintenance

problems on miniature ball rail systems,

Rexroth Bosch introduced the stainless steel

cover strip. The strip snaps in place after the

rail has been fully fastened in place. The strip

protects against dirt or other contaminants

and provides an unbroken surface to improve

runner sealing.

System integrators can now use a low

profile air table actuator just introduced by

Bimba Manufacturing Co. The small

cross-section, single bore cylinder actuated

linear table has roughly one half the height of

a standard twin bore air actuated table. The

table comes with ready to use tooling plates,

Plate 4 Rexroth Bosch VarioFlow conveyor

Plate 3 PHD Inc. PS reach and pick clamp

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Dick Bloss

Assembly Automation

Volume 22 . Number 3 . 2002 . 226–229

anodized aluminum bodies and a wide variety

of stroke lengths. A narrow profile air table

actuator was also introduced which features a

very space-efficient slide and single bore

cylinder package. The NPA is approximately

half the width of a comparable twin bore of

similar bore diameter.

Another new development from Bimba is a

high-accuracy pneumatic controller which

offers designs the ability to have closed loop

feedback control using an open architecture

with either 0-10VDC or 4-20mA command

signals (Plate 5). The controller can achieve

rotary repeatability of + 0.5 degrees and

average rotational velocity of 150 degrees per

second and linear repeatability to + 0.004in.

and average velocities to 6.5in. per second

and loads to 90lb.

A revolutionary caged ball technology from

THK America is featured in their new linear

motion guides. The ball retainer separates

and aligns the re-circulating ball bearings for a

smoother more consistent gliding motion.

The caged ball technology eliminates heat

associated with ball-to-ball friction for greater

speed and longer operating life. THK

indicates the technology is especially well

suited for medical device and semiconductor

applications.

The THK Mechatronics Division offers

custom solutions to customer needs, using

off-the-shelf elements where possible. THK

engineers employ their expertise and

application knowledge to offer solutions to

the most demanding requirements. Products

are available in stainless steel, chrome plated

or other corrosion inhibiting technologies for

adverse environments. For strict space

requirements ultra-low profile guides can be

incorporated into solutions.

A unique integral motor style linear slide

was introduced by Bayside Motion Group.

The Luge LM features a brushless servo

motor built directly onto the ball screw for

direct drive. This decreases overall length

while improving dynamic performance over

conventional mounting techniques. The Luge

features improved positioning accuracy,

repeatability and reliability. Stages are

available to 1,000mm travel with repeatability

to 5 microns. The Luge stages are also fully

enclosed for protection from environmental

factors.

Techno Inc. introduced two new low cost

CNC router systems. The new all-steel

constructed CNC routers combine brushless

servo motors and THK ball screw actuators.

The LC Series complete with CNC, work

holding table, ball screw actuation Windows-

based software is as low as US$13,995 in the

4ft 6 8ft table model. Options for the routers

include toolchanger spindles, lathe

attachment, vacuum workpiece hold down

table and laser scanner. The low cost makes

router functions available to manufacturers

who previously might not have been able to

consider the advantages of in-house

production capabilities.

For more information contact:. PHD Inc. ([email protected]).. Thomson Industries Inc. (www.

thomsonindustries.com).. Festo Corporation (www.festo-usa.com).. NB Corporation (www.nbcorporation.

com).. GE Fanuc (www.gefanuc.com).. Rexroth Bosch Group (www.

boschrexroth-us.com).. THK America (www.thk.com).. Bayside Motion Group (www.

baysidemotion.com). Techno Inc. (www.techno-isel.com).. Bimba Manufacturing Co. (www.bimba.

com).. Schunk Inc. (www.schunk-usa.com).

Plate 5 Bimba high accuracy pneumatic controller

229


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Assembly Automation

Volume 22 . Number 3 . 2002 . 226–229

Trends in the roboticsimulation industry

Greg Ahrens and

Gord Pageau

Introduction

In today’s competitive business environment,

the need for increased efficiency and

productivity permeates every aspect of a

company’s operation. In the field of robotics,

this has some companies turning toward

computer simulation and offline

programming to accelerate the design phase

of projects and to minimize the amount of

time that cells are taken out of production.

The robotic simulation industry has

responded to this need by producing products

that are more customizable, compatible,

accurate and automated. These underlying

trends can be seen in the new and innovative

functionality that has been incorporated

throughout the industry within the different

software packages.

When dealing with the field of flexible

automation it is important that your

simulation software be as flexible as the rest of

your equipment. The trend toward open

architecture can be seen in several of the

products on the market. This is accomplished

through an integrated visual basic

development environment comparable to

what is available with Microsoft’s Word or

Excel programs. The end result of this

customization is software that is configured so

that the most important and frequently used

functionality is readily available to the user.

This leads to a more efficient design that is

personally tailored to the needs of each user.

In the case of VBA customization, another

advantage is the ability to tie into the

functionality of other software packages that

also offer VBA customization. For example,

Workspace 5 allows the user to implement

functionality so that relevant data, such as a

robot’s joint values, are logged to an Excel

spreadsheet during every interval of a

simulation. These data can then be used in

dynamic calculations to analyze the

performance of the robot. This type of

compatibility is just one example of this

growing trend.

In this age of information, compatibility in

the exchange of data has become increasingly

important. This also holds true for the

simulation industry. At the heart of every

simulation package lies the 3D CAD data that

describe the objects in the cell. The ability to

use pre-existing CAD data, especially part

data, eliminates the need for remodeling and

helps to decrease the time spent on the design

The authors

Greg Ahrens is President of Automation Simulation Inc.,

Tampa, Florida, USA.

Gord Pageau is in Quality Assurance, Flow Software

Technologies, Windsor, Ontario, Canada.

Keywords

Simulation, Robotics, CAD, Computer software

Abstract

The need for increased efficiency and productivity has led

many companies towards computer simulation and offline

programming to accelerate the design phase of projects

and to minimize the amount of time that cells are taken

out of production. The robotic simulation industry has

responded to this need by producing products that are

more customizable, compatible, accurate and automated.

These underlying trends can be seen in the new and

innovative functionality that has been incorporated

throughout the industry within the different software

packages. Describes robotic simulation software being

used in design for assembly as well as some industry

trends.

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DOI 10.1108/01445150210436437

of a cell. All of the major simulation packages

offer neutral CAD format file importing, such

as IGES or STEP, but the trend has moved

towards Native CAD file importing or

translating. The elimination of the neutral

format in the exchange between two CAD

systems increases the accuracy and usefulness

of the resulting part. But the accuracy in the

CAD information is just the first step in

creating an overall accurate cell that is needed

for off-line programming.

Since most of the information that is sent to

the robot during offline programming is

positional data, it is important that the model

is an accurate representation of the real world,

and this begins with the robot. In the

assembly of every robot there are allowable

tolerances that affect the kinematics of each

individual robot. Because of these tolerances,

most simulation packages allow for some type

of robot calibration where the true kinematics

of a particular robot are measured and stored

with its own unique model. This involves

connecting the robot to some type of

measuring device and then exercising each of

the joints through a range of motion. The

positional data recorded by the measuring

device are then compared to the actual target

data to determine the variations in the

kinematics. Once the kinematics of the robot

have been modeled accurately, it becomes

possible to use the robot as a measuring

device in order to improve the accuracy of the

relative distance between the robot and the

other objects in the cell. Workspace 5 has a

system wherein objects in a model can be

repositioned by matching up two sets of robot

targets, each containing three points. One set

of points is located on well defined features on

the modeled part within the software, while

the other set is taught in the actual cell by

moving the robot to each of the

corresponding features on the part in the real

world. These points are then imported from

the robot’s controller into the software, and

the modeled part is adjusted so that the two

sets of points match up. The positional

information in a modeled robot cell, such as

the one described, is not the only area of

robotic simulation where accuracy has been

improved. Advances in the accuracy involved

in the motion of the robot have also been

made.

Every robot manufacturer has its own

proprietary motion control software,

therefore, each simulation package must have

its own motion control software as well. The

differences between the motion control

software used in simulation and the ones used

on the factory floor lead to discrepancies in

cycle time and the robot’s actual path. RCS

(based on the realistic robot simulation

specifications) modules now allow simulation

software packages to use the same motion

control software that is found on the robot

controller. RCS modules are available

through the robot manufacturer and can be

plugged into robotic simulation packages

such as Workspace 5. The use of the robot

manufacture’s motion control software

insures more accurate cycle times and

predictable paths (within + 3 percent for

cycle time and within + 0.00005 radians for

reference).

The latest trend in robotic simulation is to

automate as much of the process as possible.

The most prevalent examples of this are

automatic robot positioning, automatic tool

selection and automatic path generation. The

automatic robot placement is fairly

straightforward and is based on the location

and orientation of the robot targets that have

been created. The software searches and finds

the optimal position such that all of the

targets are within reach. The software

engineers realized that it is much easier for the

computer to run through a search algorithm

than for the user to test out different positions

one at a time (Figure 1).

Automatic tool selection is a little more

complex and is usually only offered in

conjunction with spot welding guns. It

Figure 1 An ABB robot used for a material handling application. This was

for an oil pan leak test station and workspace was used to determine

reachability. Workspace 5 was used to optimize the robot placement

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Trends in the robotic simulation industry


Assembly Automation

Volume 22 . Number 3 . 2002 . 230–234

involves sectioning the part to determine the

physical demands on the tool as well as

looking at the weld requirements for the tool.

It uses these parameters to search a database

of tools and offers the user the tool it thinks is

most appropriate for the job. Both of these

automated processes can help speed up the

design phase of a project, but neither has the

impact on efficiency that automatic path

generation does. Automatic path generation

creates a path for the robot based on part

CAD data and the constraints set by the user.

In this way, an entire path can be created in

one step. When dealing with applications

such as waterjet cutting, where paths contain

large numbers of robot targets, the time saved

by not having to create the points individually

is enormous (it has been measured at

90 percent for certain examples). It allows the

user the ability to test out different paths in

order to optimize performance and reduce

cycle time as opposed to using the first

solution that is achieved, which is so often the

case when programming robots by hand

(Figure 2).

Though these trends in robot simulation

have led to more efficient products, the true

benefits of simulation are seen when

compared to not using robot simulation at all.

Mark Bevins, CEO of CIS Robotics and a

Workspace 5 user states: ‘‘Before, we were

experiencing between 20 to 50 hours of online

programming time per hour of robot cycle

time. That has been reduced to about five to

ten hours online since we started using

simulation and offline programming software,

and with the new products on the market we

are looking to reduce that even further.’’ In a

business environment where cost cutting has

taken such a high priority, the robotic

simulation industry has responded by

producing products that continue to improve

efficiency in the production cycle.

Using Workspace 5 to take design forassembly to the next level

Let us assume for a minute that your

company has designed a sub-assembly for a

customer. Now strictly speaking, it meets all

the constraints set forth in their engineering

specifications, but is it the optimal solution?

Well one way to find this out is to test the

methods of manufacture for various revisions

of the individual parts as well as the assembly

as a whole. A manufacturing simulation

package such as Workspace 5 can do just that.

As an example let us look at a small

subassembly made up of four distinct parts

and let us assume that two of these parts will

need to be manufactured internally. A

comparison of alternatives can be set up using

a simulation package. The proper work cell

CAD can be defined, or just imported from

the automation vendor. Then things like

specific tooling, safety equipment, arrival

rates and service rates can be examined.

Using valid data for variants such as arrival

rates one can increase the accuracy of the

simulation to a point where the results would

be significant to their design process.

However, even if accurate or historical data

can not be found or does not exist, a direct

comparison of alternatives can save time and

money.

Far too often the cycle time of the part is the

only concern when simulation is being

considered. If this was our only concern then

a discrete event simulation package could be

used, but there are many other costly

problems associated with a work cell.

Everything from tooling design to cell input/

output could be examined using a desktop PC

rather than interrupting production.

Minor adjustments can be made in part,

tooling and fixture design. If we have

imported a part from a high end CAD

package we can now determine a tool path for

the manufacturing process (Figure 3). Once

this has been accomplished, collision

detection can be run for the entire cell so as to

Figure 2 Two Motoman robots being used for a waterjet cutting

application. The parts in this case were plastic automobile interior panels.

Workspace 5 was used as an offline programming tool

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Volume 22 . Number 3 . 2002 . 230–234

prove the viability with either current or

future machinery. As an example, a path for

the manufacturing process may not be

possible if the fixtures are getting in the way

and it is less costly to find this out now.

It is fine to say that resulting cycle time for

part one is ‘‘x’’ seconds, but where simulation

software really shines is in running what if

scenarios. Before money is spent on either

outsourcing of production or automation to

an existing facility, someone will need to sit

down and determine the cost effectiveness of

any potential solutions. With packages such

as Workspace 5 the end user can do this for

itself rather than just depending on the

accuracy of its vendors. There just may be too

many unknown inputs for an outside vendor

to properly cost out a job, but there are many

cases now where even the vendors, both small

and large, will do this simulation work

themselves before agreeing to the viability of a

given design. On a larger scale, the end user

can determine potential bottlenecks in the

manufacturing of these assemblies by running

simulations of either entire lines or controlled

areas of the plant.

Beyond industrial robotics, Workspace 5

can handle all sorts of peripheral devices. Belt

and gravity fed conveyors can be used to

transfer parts in and out of the work areas as

well as for buffering purposes (Figure 4). For

the purposes of an accurate reflection of the

real world workcell part feeders can be

utilized. Turntables and positioners can be

controlled as external axes on the robots or as

distinct devices, depending on the situation.

Even if the cell is an existing one there may be

major changes necessary to adjust for an

engineering revision or prepare for the newest

model. Tooling design and positioning of

fixtures are two that come to mind

immediately (Figure 5). So that even if a final

assembly has been designed, engineering

analysis has been done to prove its strength

and the marketing department has signed off

on its colour scheme, the simple fact remains

that the part may not be possible to

manufacture without serious expense.

While the final assembly is very important

in terms of human hours and time to market,

we need simulation at some point unless the

Figure 3 Two Motoman robots used for a waterjet cutting application. The

parts being prepared in this case were vehicle headliners for an automotive

supplier. Workspace 5 was used to determine optimal part placement

Figure 4 Two ABB robots used for a material handling application. This

was for a palletizing area of the plant to test for reachability and cycle

time. Workspace 5 was used to determine potential throughput

Figure 5 A Panasonic robot was used for an arc welding application. The

part being tested was a subassembly to be used in a larger assembly.

Workspace 5 was used for proof of concept

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Volume 22 . Number 3 . 2002 . 230–234

more costly trial and error method is to be

used. Think back to the day where parts were

designed independently of each other and

assemblies were not tested out on computers.

A computer-based solution can now take this

to the next level, as we can easily prove out an

assembly in CAD software the next obvious

step would be to make sure that it is possible

to manufacture.

Workspace 5 enables the user to quickly

change from one tooling design to the next

without so much as milling a single piece of

aluminum. Not only can we directly see the

cost savings associated with digital

manufacturing, but we can also work

concurrently so as not to effect the plant floor.

Internally, at Flow International, there have

been many recent cases of one division doing

all the design and build work while another

does the simulation in a different geographical

location (saving a total of two days robot

programming and part positioning time in the

most recent case).

The software itself has many tools built in

to save manual work as well. Workspace 5

uses an automatic path generation command

to enable the user to create tool paths from

simple CAD objects either imported or

created directly in its environment. If

comparative parts are being used then we can

also re-use one tool path and program with a

copy and paste, thus enabling the user to do

the work only once per work cell and not on a

per part basis. The open ended VBA side of

the software can also be used to facilitate

change at a more rapid pace. Using everything

from basic macros to complex user forms can

result in information being passed into and

out of the simulation without the end user

even noticing.

So assuming the process has been

optimized for reach problems, cycle time, as

well as other key areas, the next and equally as

important step is to do something with all

these data. We will assume that the proper

steps have been followed throughout the

simulation process and that every number, no

matter how significant, has been validated in

some method, we can then use CAD import/

export functionality to maintain the work we

have accomplished. Sending these data out to

another package for design revisions or even

manufacture is what separates manufacturing

simulation from simple process simulation.

Although the validity of the numbers should

be equal, why would the end user want to do

all that work only to repeat much of what they

have accomplished in a second package?

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Assembly Automation

Volume 22 . Number 3 . 2002 . 230–234

Robots great and smallat Hanover

Anna Kochan

The robotics and automation sector is one

that never ceases to evolve and innovate.

Robots continue to feature higher speeds,

greater payloads and improved accuracy. It

was all to be seen at the Hanover Fair, the

event which has become a state-of-the-art

showcase of the industry.

Most innovative at this year’s Hanover Fair

was new vision technology from Isra. The

German company showed its new visual servo

product that is designed to enable robots to fit

parts onto a vehicle as it moves continuously

along an assembly line. ‘‘Most vehicle

manufacturers today stop vehicles on the line

at each point where robotic assembly takes

place. That adds to the cycle time and costs

money. The market is definitely looking for a

non-stop concept’’, says Isra chairman,

Enis Ersu.

Isra’s solution, the visual servo, is based on

a Kuka robot and Isra vision system to track

the vehicle as it moves. The challenge,

according to Enis Ersu, is to achieve a control

loop between the robot and the vision system

that is very high speed. He claims that Isra has

achieved a control loop that cycles at

100-200Hz. Kuka is currently Isra’s preferred

robot to work with since it has has the most

advanced controller, he adds.

The first visual servo installation, expected

towards the end of 2002, will carry out those

moving assembly tasks that make lowest

demands on accuracy, such as the placing of

the spare wheel in the boot or the location of

the battery in the engine compartment. These

tasks, says Enis Ersu, only require + 1mm

accuracy. However, he expects Isra to have

mastered visual servo for the higher accuracy

applications by the end of 2003. The

positioning of cockpit modules and seats, for

example, requires tolerances of + 0.5mm.

Isra is continuing to develop its vision

solutions in other areas. A future application

for Isra technology is the inspection of gap

and flush on cars. A first attempt at a solution

has just been delivered to VW for test.

However, it is only able to check gap and

flush where a metal panel ‘‘meets’’ another

metal panel. A solution for metal-to-plastic or

glass, such as in the headlamp area, is still in

development.

Like Isra, manufacturing equipment

specialist Comau has a strong interest in the

automotive market. The Italian company has

decided to join the select club of robot

builders offering a model with a 500kg

The author

Anna Kochan is European Associate Editor for

Assembly Automation.

Keywords

Assembly, Pick-and-place, Robotics, Machine vision,

Automotive components industry, Food industry

Abstract

Reports from the Hanover Fair on new developments in

automated assembly technology, particularly robotic

assembly, outlines the latest robot hardware and software

innovations to be launched on the market, describes new

applications being taken up by industry.

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DOI 10.1108/01445150210436446

payload. To date, only Kuka and ABB have

introduced robots of this size. Comau’s

version, the Smart X1 (see Plate 1), is

however, just the first of a new family that

will, over time, offer payloads up to 700kg

and reaches of up to 3.5m. This is the plan, at

least according to Arturo Baroncelli,

marketing manager for robotic welding

systems, who claims that the Smart X1 ‘‘is the

strongest robot in the world’’. Although the

product is new, the technology already exists

in other Comau robot families such as the

H4, he adds. Comau has shown the first X1

robot to selected customers and has already

received about ten orders. ‘‘We have

developed the X1 for bodyshop applications.

It is strong enough to handle complete car

bodies, which are both large and heavy, and

to manipulate complex fixtures’’, explains

Arturo Baroncelli.

Also targetting automotive bodyshops is

German company SEF, which builds the

VW-designed robot. It highlighted laser

welding applications on its stand at the

Hanover Show. In one demonstration (see

Plate 2), two SEF robots equipped with laser

sources from Berlin company High Yag

carried out laser welding operations on a door

that was being held in place by a third robot.

The cell was set up for the exhibition to show

the potential of laser welding robotics, says

Frank Wrede, manager of technical sales at

SEF. He sees a great potential for laser

welding in the automotive industry. ‘‘The

new generation of cars will feature up to

70 per cent laser welding’’, he comments.

Elsewhere on the stand, SEF showed a

remote laser welding cell with a 2.4m 6 1.5m

working envelope that it has developed with

laser supplier Rofin-Sinar. According to

Frank Wrede, more than five of these cells are

already installed in the automotive industry.

New laser welding solutions were also

demonstrated by Reis but for joining plastics

rather than metal. In one demonstration, a

Reis RV16 robot used a Prolas diode laser to

join automotive rear light coloured glasses.

The specific feature of the RV16 robot is the

integration of the laser beam guidance system

into the fourth axis of the robot arm. Due to

the central exit of the laser beam at the

flexible wrist, Reis was able to omit the sixth

axis of the robot and to use the space for beam

guidance. Developed in collaboration with

Prolas and Thyssen Lasertechnik, the

solution gives the advantages of compactness,

flexibility and speed.

Reis also exhibited CO2 laser welding for

plastics parts, claiming that its five-axis

RV16L articulated robot is unique, due to the

integration of the beam guidance system

within the robot arm. The laser beam,

generated by the CO2 laser source mounted

on axis three, is guided via mirrors and a

beam-shifting element to the head axis of the

robot, where it enters the cutting optics. Reis

claims that this very compact design allows

short beam ways, process-safe beam

guidance, unlimited movement of the robot

and excellent access to components.

On its stand at Hanover, Reis also

announced a brand new robot kinematics. By

mounting a five-axis articulated robot on a

linear axis to create the new KRVL16, Reis is

attempting to offer the ideal solution for

machine load/unload operations (see

Plate 3). A five-axis solution compared to the

more common three-axis one allows

Plate 1 Comau joins the league of heavyweights with its Smart X1 but

promises even greater things

Plate 2 Demonstrating the laser-welding of doors with three robots

working collaboratively

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Robots great and small at Hanover

Anna Kochan

Assembly Automation

Volume 22 . Number 3 . 2002 . 235–238

workpieces to be handled in more flexible

ways, says Volker Wunsch, sales manager –

handling systems.

Also new from Reis is a software feature

known as Safe Production that enables an

operator to remain in a robot cell while it

continues to run in fully automatic mode but

at a reduced speed (see Plate 4).

The safety function is integrated with the

ROBOTstarV robot controller. Safetycontroller

software monitors the axis speeds of the robot

and reduces them so that operators can observe

the process in close-up and intervene in it

directly without having to interrupt the

automatic operation.

So far, Reis has developed three modes of

Safe Production operation:

(1) An installation running automatically at

full process speed slows down to a

personnel-safe speed as soon as an

operator enters the cell to observe the

process or perform other tasks. This is

particularly useful for maintenance

personnel who may have little experience

of operating the installation.

(2) The work envelop of the robot is divided

into two areas, one where the operator

has no access and the robot speed is not

subject to limitation, and one where

operator access is permitted and where

the reduced speeds apply during operator

presence.

(3) The robots are operated without separate

safety devices, and the man and machine

work hand-in-hand with a firmly

programmed speed. For example, the

robot takes over the handling of heavy

parts while the worker executes assembly

or machining tasks.

Volker Wunsch claims Reis is the first in the

world to offer a control function of this type.

New software developments were also

highlighted by Fanuc at the Hanover Fair.

Olaf Gehrels, executive vice president of

Fanuc Robotics Europe, described a new

software feature called Approach Deterrence

as a way of optimising robot programs so that

cycle times are kept to a minimum and space

utilisation is maximised. It is particularly of

benefit when programming a number of

robots that are working in the same space, he

said.

Conventionally, collision avoidance is

achieved by tracking the locations of tool

centre points. This, says Olaf Gehrels, does

not take account of the complete robot

structure. Using Fanuc’s Approach

Deterrence feature, however, virtual models

Plate 3 Reis mounts a five-axis robot on a linear axis to

create an automated solution for machine load/unload

Plate 4 With Reis’ Safe Production feature, the operator

can observe a robotic process from close by

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Volume 22 . Number 3 . 2002 . 235–238

of the entire robot structures are used. Virtual

models of component feeding equipment can

also be introduced, should these have an

impact. As a result, robot cells can be

programmed in a more flexible manner to

achieve more compact layouts,.

Also new from Fanuc is a high-speed

packaging robot suitable for handling small

parts such as chocolate bars. Based on the

design of the existing M400 packaging robot,

the new M420iA has a 40kg payload and is

capable of 3,000 cycles an hour, whereas the

M400 can only perform 1,800 cycles an hour.

Fanuc claims the M-420iA is 25 per cent

faster and can carry 30 per cent more weight

than competitive robots. The three-robot cell

demonstrated at the Hanover Fair is, in fact,

due to be delivered to Ion, a Greek chocolate

manufacturer, later this year. Developed by

German systems integrator Paal, the cell will

package 900 chocolate bars per minute.

A relative newcomer to the robotics market

in Europe is the Japanese manufacturer

Denso – although it is one of the market

leaders in Japan. A specialist in small robots

(payload up to 20kg) for assembly and

pick-and-place applications, Denso has

delivered a total of 20,000 robots of which

6,000 are operating in the company’s own

automotive component production plants in

Japan. Denso is now making inroads into the

European market, with a market share in

Europe that doubled in 2001, according to

Jeroen van Asten, sales and marketing

manager – Denso Europe, and he is ambitious

about maintaining or even increasing this

growth rate. Having already established six

system integrator partners in Europe, Jeroen

van Asten is now aiming to increase this to 20

in the next few months. He is particularly

looking at Germany, the UK, Italy and

Scandinavia. The applications Denso targets

are many and varied, ranging from food to

automotive.

Last year, at the Hanover Fair, Denso

introduced its family of six-axis robots. This

year, it was a family of four-axis robots that

made their debut (see Plate 5). According to

Jeroen van Asten, no other four-axis robot on

the market matches the new Denso range in

terms of speed and accuracy. He claims a

cycle time of 0.35sec. or 0.29sec. for the

larger and smaller members of the four-axis

robot family respectively, compared to the

0.5sec. of competitors’ products.

Repeatability ranges from + 0.015mm to +0.025mm, depending on the model.

Plate 5 Denso adds four-axis range to existing six-axis family

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Assembly-initiatedproduction – a strategyfor mass-customisationutilising modular,hybrid automaticproduction systems

Anders Karlsson

1. Introduction

In this article, manufacturing is seen as

operations directly involved in creating a

product. To simplify matters, assembly is

seen as a part of manufacturing. When

addressing assembly specifically, the term

assembly is used. There are, however, many

other different definitions of manufacturing.

One very important factor, needed to

succeed in the field of production, is the

presence of an overall valid strategy that takes

into account future trends, market demands

and technological development. Otherwise

one will possibly repeat mistakes made by, for

example, Ford when missing the need to

adapt to changing market requirements. A

very good example is the Toyota production

system, which had clear goals and ways how

to reach them. Assembly-initiated production

(AIP) aims at being such a strategy.

The project foundations lie within the ideas

generated by current trends in industry,

existing just-in-time (JIT) philosophies, and

the modular function deployment

methodology (Erixon, 1998). With current

philosophies and methods as a starting point,

the program aims to describe a new

production strategy, and methodology, with

particular focus on assembly.

Trends that have been identified as

important issues when developing AIP are

(Karlsson and Onori, 2000):. Shifting production volumes, must ramp

up and down very quickly in response to

the order volumes (large capacity

fluctuations).. Shorter product life spans (frequent

system reconfigurations).. High, and continuously increasing

number of product variants.. JIT delivery.

The author

Anders Karlsson is at the Royal Institute of Technology

(KTH), Department of Production Engineering, Assembly

Systems Division, Brinellv, Sweden.

Keywords

Assembly, Hybrid systems, Customization

Abstract

The assembly-initiated production (AIP) project aims at

developing a strategy for mass-customisation with short lead

times through the production. The presented results are the

outcome of cooperative work between KTH and 19

companies of different sizes, active in Sweden. AIP is formed

around the idea to assemble products from product modules

on customer orders. The total delivery time would be time to

process order + assembly time + shipping-time. This gives a

total delivery time considerably shorter than when

manufacturing the entire product to order. There are many

factors to consider. Challenges like modularising the

products to fit the strategy, finding ways to automate

assembly and manufacturing operations, and at the same

time, accomplish a flexible production solution. There are

also many other factors to consider being successful in mass

customisation, like materials supply and material handling

issues, information system design and creating a suitable

organisation form. Of utmost importance is the way the

factors affect each other and the production as a whole

when changes are made.

Electronic access




available at


Research article

This work was financially supported by

Woxencentrum and The Royal Institute of

Technology, Stockholm, Sweden.

Great contributions to the results presented here

were made by people from these companies, here

in alphabetical order: ABB Corporate Research,

ABB Future Center, ABB Motors, ABB Power

Systems, ABB Robotics, ABB Switchgear, ABB

Ventilation Product Division Stratos, Alfa Laval

AB, Atlas Copco Tools AB, BT Products AB,

Ericsson Radio Systems AB, ESAB Welding

Equipment AB, ITT Flygt AB. Gustavsberg

Vargarda Armatur AB, Posten AB, Rexroth

Mecman Svenska AB, Segerstrom & Svensson AB,

TUBE Control AB and Volvo Truck Corporation

AB.

239

Assembly Automation

Volume 22 . Number 3 . 2002 . pp. 239–247


DOI 10.1108/01445150210436455

These trends put different requirements on

the companies and their production. The AIP

strategy is being developed to take these

factors into account and to do this

comprehensively, it has to include all areas

involved in the production:. Reconfigurable manufacturing systems.

For example, there is the need for

stepwise expandability and the possibility

to adapt to different products (Onori et

al., 1999).. Product designs that assist the production

processes, and at the same time, result in

products attractive to customers.. Information systems that are designed to

support the processes. This means that

the information systems themselves have

to be reconfigurable in the same manner

as the processes.. A supply chain that supports the

manufacturing processes and that

strengthens the production as a whole.. Competent and flexible personnel to

enhance the characteristics of the rest of

the production system. They must have

the ability to identify different situations

and to react in a suitable way.. Other personnel-related subjects like

human-machine interfaces, working

environmental issues, etc., have to be

taken into account when creating the

system.

As one can see, AIP is designed in line with

issues normally associated with mass

customization. Mass customization emerged as

manufacturers, enabled by their proficient lean

production systems, explored ways to better

meet the needs of customers (Alford

et al., 2000). Going from mass production to

mass customization requires a total

reengineering of the company. A reengineering

is basically enacting multidimensional change

to achieve dramatic improvements in

performance. To be fully capable of supplying

unique goods and services to customers as a

planned strategy without sacrificing cost

control, product quality or delivery speed,

companies must actively redesign business

processes for the era of mass customization

(Gilmore, 1993).

2. Assembly-initiated productionstructure

Figure 1 describes the functions of the AIP

structure.

(1) The customer order enters the computer

system and is immediately available to the

entire manufacturing chain, although the

final assembly is where the order is

retrieved and the manufacturing is

initiated. Any sales department involved

should have its work immediately

registered to avoid increased lead times.

(2) The final assembly will be able to see

which orders are in the system at an

earlier stage. This will lead to a more

responsive production.

(3) One of the central concepts about AIP is

the modularization of products. The

modules and standard components will

be stored close to the assembly. When an

order is to be executed, components and

modules will be taken from the storage

and assembled into products.

Figure 1 The AIP structure

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Anders Karlsson

Assembly Automation

Volume 22 . Number 3 . 2002 . 239–247

(4) The finished products are, after the

assembly, packed and delivered to the

customer.

(5) The module storage is set just before the

module (assembly) workshops. To avoid

delays, the module workshops will have to

be able to deliver the modules required by

the assembly workshops at the correct

rate.

(6) The demands placed on parts

manufacturing and ordering of

components from sub-contractors are

basically the same as the ones placed on

modular workshops.

One should note that the sub-contractors

could deliver to any station in the chain. That

is, they could deliver raw material or

components at different levels of completion,

from simple components to product modules

as well as material not directly included in the

final product, like packaging material.

What AIP introduces is the possibility to

give a product its final identity as late as

possible within the production chain. This is

of great value in a world in which the product

variant is commonly created in parts

manufacturing, with ensuing buffers and

warehousing problems. It becomes obvious,

then, that the application of AIP strategies

requires a highly reactive, order-driven

control system and equally efficient assembly

workshops. Assemble to order is, as a

manufacturing principle, far from new. The

originality of the AIP project is to use

assembly to order to solve today’s problems

with technology available now or in the near

future.

The predominant solution to be preferred,

as long as the product features allow it, is the

cell or assembly workshop. Basically, an

efficient final assembly requires an equally

efficient set of sub-assembly or module-

assembly units. That is to say that, if AIP is to

become a successful tool, equally reactive and

truly flexible assembly solutions must be

developed.

3. AIP related production requirements

In this chapter, an overview of what is

required from different manufacturing-

related areas is presented.

The amount of variants produced at each

stage greatly affects the constraints and

demands put on the system respectively. In

Figure 2 the module manufacturing (D, E

and F) and assembly (C) are divided into

cells. These cells should be easily

reconfigurable to be able to meet the current

customer demands (Figure 3).

The necessity to be able to reconfigure the

systems is enhanced in the final assembly

since there a much larger variant variety will

be produced. To make this possible, these

basic properties of the manufacturing system

are looked at in a wider sense.

3.1 Materials supply

Support for the AIP strategy has been found

within supply chain management (SCM).

Balsmeier and Voisin (1996) classify SCM as

formal linkage among all levels in a marketing

channel; it is a technique that looks at all the

links in the chain from raw material suppliers

through various levels of manufacturing and

distribution, to the final customer. SCM may

be seen as an overall strategy for all parts in a

supply chain, including manufacturing and

assembly. This becomes clearer when looking

Figure 2 A detailed AIP application example

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at Otto and Kotzab’s (1999) condensation of

SCM principles:. Compress. Reducing the number of nodes,

members or actors in the chain or by

reducing the physical distance between

any two nodes.. Speed up. Reducing the amount of time

necessary to move between any two nodes

in a chain or a network or between two

stages in a process.. Collaborate, cooperate. Increasing the

intensity and scope of cooperative

behavior between two or more

independent decision-making units.. Integrate. Reducing the penalty in time,

effort, cost or performance to move

between any two activities in a process or

between processes.. Optimize. Maximizing the value of a

target function through the use of

quantitative models and methods.. Differentiate, customize. Increasing the

specificity and thus the effectiveness of a

subject towards a given purpose.. Modularise. Reducing the penalty in time,

effort, cost or performance to replace a

particular segment of the chain.. Level. Reducing the magnitude of

variation of a certain parameter of an

object over time.. Postpone. Moving the product

differentiation closer to the time and

locus of consumption.

SCM also shows some of the main ideas of

AIP. A comment has to be made about the

level principle. In AIP, there are no goals as to

leveling the daily amount of production over a

period of time. The variations due to shifting

volumes, new products introduced, different

product variants, etc. should be dealt with by

having a flexible production system and by

product design. Otherwise the lead times will

be longer than necessary. The manufacturing

of parts and modules (C, D, E and F in

Figure 2) will automatically be more leveled

since they will manufacture only a few

variants of modules which will be more even

in volume than the manufacturing of the same

end products within a department layout

factory would be.

One problem found in supply chains is the

bullwhip effect. The bullwhip effect is the

amplification of order variability along the

supply chain. The closer to the first link in the

chain, the larger the variability (Lee and

Padmanabhan, 1997). The effective way to

eliminate bullwhip effect is by allowing viable

information to be available and to create short

delivery times. Both are built-in features in

the AIP strategy and therefore bullwhip effect

should be of little or no concern. The

reduction or elimination of the bullwhip effect

reduces the need for capacity flexibility within

the automated production equipment. This

without lessening the total capacity flexibility

of the production, indirectly demanded by the

customers.

Figure 3 A rough sketch of how the relative amount of different variants of components or products are being

produced through an AIP production flow

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3.2 Information handling and use

Product data management (PDM) systems

originate from engineering aspects of product

development, so the systems mainly deal with

product engineering related data. PDM

systems rarely use and treat data like, for

example, sales, costs, supply-issues or

manufacturing control (Peltonen, 2000).

PDM is very much about managing

configurations and changing of

configurations. Considering the goals with

AIP regarding the possibility of producing

many different product variants and different

volumes, the availability of accurate and

quickly accessible product data is of utmost

importance. A PDM system should therefore

be seen as an integrated part of the

information system in Figure 1.

The question as to how to design the

production planning and control (PPC) for

AIP production arose early in the pre-study

phase, considering all the problems related to

PPC noticed. Among the problems that have

been identified are (Karlsson and Stromberg,

1998; Karlsson, 1999):. Little or no control over the actual

situation.. Lead times, given by the PPC system,

were often inaccurate.. PPC systems are not designed for the

given type of production or the way the

companies produce.. Unfriendly user interface of PPC

software.. The real material flow does not comply

with the model in the system.. Poor or nonexistent handling of rush

orders.. The system is often considered a burden

rather than a helpful tool.

These problems have to be solved and, as the

work proceeds, more problems will most

likely appear. To be able to decide what

system or principle to use, a review of the

benefits and limitations of each system was

necessary.

Materials requirement planning (MRP) is

flexible in terms of products and floor layout,

but contributes to long lead times and large

inventory levels. JIT-associated methods, on

the other hand, have a narrow range of

product and layout flexibility, but build up

minimal inventory levels and give a short lead

time (Plenert, 1999a). At the same time there

are many other principles to be considered,

e.g. bottleneck allocation methodology

(BAM) (Plenert, 1999b) and theory of

constraints (Goldratt and Cox, 1986;

Goldratt and Fox, 1986). Differences do exist

between the MRP based software systems

themselves, each exhibiting its own strengths

and weaknesses (among others, Shotten and

Kees, 1995). In order to gain the required

benefits, JIT methods will most likely be an

adequate alternative in many parts of the

production, and the limitations of little or no

concern. Parts of the production will have a

more stable order situation (C, D, E and F in

Figure 2) than the final assembly, which may

give the opportunity to use, for example,

kanban control.

The suggested solution is a more

decentralized control concept within the

company with a more modular approach

where each sub-control system covers only a

part of the production system. The expected

benefits from such a system approach is that

such an architecture provides departments

with better opportunities to incorporate their

specific planning requirements in the control

system. This would make the PPC system to

support the inherent characteristics of AIP.

3.3 Human resources in manufacturing

Although being a very important area, an

in-depth look at this research area has been

outside the scope of the AIP research so far.

This means that there are no solutions

suggested here, but important issues are

identified and discussed. It was clear in the

pre-studies that the areas concerning human

resources have a considerable impact on the

performance of the production. It is,

therefore, a research area to put efforts into.

In the pre-study phases, different

personnel-related issues were identified.

These are divided into the following areas:. Organizational issues. The division into

work groups, formal and informal

channels for information distribution,

authority, etc.. Competence issues. Education, knowledge

about operation and the products,

choosing an education and knowledge

level on the employees.. Work environmental issues. The creation of

a workplace that is stimulating to work in,

forming a workplace layout that promotes

effective manufacturing, working to

reduce and avoid work-related injuries,

etc.

The areas interact in different ways, which is

also to be considered.

Estimations on possible additional costs

related to changes in the workforce have not

been made, since such costs would be highly

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related to a specific case. The AIP project has

so far been general to its nature.

3.4 Manufacturing processes

One has to get flexibility out of the production

equipment. Some may be able to do that by

using their ordinary machinery, depending on

machinery available and the product

manufactured. In the companies within the

pre-studies, it was observed that using manual

operations was bringing about a great deal of

the necessary flexibility in assembly

operations. This is rather common in the

industry and especially when it comes to

assembly. AIP, however, does not specify the

use of manual or automatic processes.

To find a suitable solution to flexibility

problems in automatic assembly, the AIP

project has been performed in cooperation

with the Hyper Flexible Automatic Assembly

project (HFAA) (Onori and Alsterman,

2000). HFAA describes a concept consisting

of a set of equipment modules, with

standardized interfaces. The benefits to be

gained from a standardized solution are

many, among others:. Shorter installation times.. Lower investment costs and related risk

factors.. Simpler re-configurations of original

layout.. Second-hand market equipment.

This entails that mechanical, electrical,

pneumatic, electronic and software interfaces

must be standardized, be of a common

format, description, etc., and allow the

transport of the particular medium (software,

air, etc.) without adjustments. This also

entails that the physical dimensions of the

particular equipment are such that the unit

may be inserted into any assembly system

without requiring particular modifications

(Sandin and Onori, 2002). For this purpose,

standardization guidelines have been

developed, consisting of six elements that

together define the standardization levels

required. The elements are (Sandin and

Onori, 2002):. documentation;. availability;. recognition;. update;. validity;. sector management.

This makes it easier and more affordable to

rearrange automated equipment to create

flows that fit the current order situation. AIP

does not put any additional demands on the

assembly equipment that are not addressed in

the HFAA project. They are, on the contrary,

quite similar.

There are many other projects, finished and

ongoing, that are addressing these problems

as well. One should note that the AIP strategy

is not limited to a certain set of solutions. It is

important to fulfill the requirements of the

AIP strategy, not to use a certain solution.

The design of the process is closely related

to the product design and is putting

constraints on each other. The degree of

dependence differs from case to case.

Production equipment that is able to adapt to

the production of products matching the

current order situation would lessen this

dependence, or at least the effects from it.

3.5 Product design

A modular product design is a part of the AIP

strategy. Modularization is the decomposition

of a product into building blocks (modules)

with specified interfaces, driven by company

specific reasons, called module drivers

(Erixon, 1998).

Analysing module drivers, the primary

drivers for AIP are to be able to combine

modules into products with different

specification, different styling and that are

sharing common units among variants.

Basically, they are central building blocks of

the AIP strategy. They make it possible to

create product variants within the final

assembly.

Second, to improve overall flexibility of the

production, the drivers carry-over of modules

to new products, planned design changes,

technical advancement during the product

lifetime and the possibility to outsource are

important. The choice made by a company of

which module drivers to be considered

important affects the choice of modules and

hence, the product design. Standardization of

parts that are not to be modules is included in

the design process.

An observation made on participating is

that the technical properties of a product or

product group as well as customer

requirements influence the possibility to

modularize products. Common for the

participating companies are the need to

compete by being able to deliver customer

specific products and, at the same time,

having short delivery times. The products are

high quality and high price products, sold to

other companies. The high price still means

that one has to compete with other

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companies, which are manufacturing similar

products, sometimes by reducing prices, be it

pneumatic hand tools or trucks.

There are also many different ways to ease

production by designing the products to the

specifications of the manufacturing

equipment. Use of design for X, including

design for manufacturing and design for

assembly methods, will contribute to the

overall flexibility and performance of the AIP

system.

3.6 Concluding words on requirements

The goals with AIP put needs on the

manufacturing system to be very flexible in

terms of capacity and to handle new products

and different product variants. The maximum

capacity and flexibility should be seen as the

sum of the capacity and the flexibilities from

the product design and the manufacturing

system. Human resources directly involved in

the manufacturing are also included. The

other areas presented here (information

handling, material supply and human

resources) should support this and not

hamper the overall performance of the

production, which is very common today.

The suggested AIP structure supports the

use of stepwise expandable manufacturing

systems. The structure makes it easier to

choose between manual and automated

processes and also combinations (hybrid

systems) thereof. It would also be possible to

incorporate disassembly cells within the

manufacturing due to the built in flexibility of

the production.

To give details on numbers concerning, for

example, buffer sizes, product module

structures, costs and such, are subjects for

more detailed projects, researching the

possibilities to implement AIP in specific

cases. Therefore it is left out at this stage,

which is devoted to strategy development. It is

an essential step within the AIP project,

however, to present means for system design

and it will be subject to more research. First

steps have been taken to design such a

method in the form of developing a

theoretical model.

4. Transferring AIP theory to amanufacturing system model

The first goal has been to provide a theoretical

model that could be used when mapping

important characteristics of a planned

manufacturing system.

The first stage is a design of a generic set

structure that is to describe input, output and

the influence the set has on its environment.

The set structure is to describe a chosen part

of a manufacturing system. The set structure

is called functional process area (FPA).

The central point in this method is the

process. The process is here measured and

specified by the:. input, like material and resources;. output, which is the product or partly

manufactured product;. influence the process has on its

environment.

These factors are set by the performance of

the process itself. To be able to select these

three factors, one has to decide what to

measure within the process and how to

measure it. The total of the input, the output,

the influence and the process itself is here

called FPA. An FPA is depicted in Figure 4.

To be able to characterize the set content of

the FPA, the following division of

manufacturing areas has been made. These

manufacturing areas correspond to those

presented in chapter 3:. Supply, which is the area of supplying

material and components to the process.

It also involves the transportation of

manufactured goods from the process. A

large part of the area of logistics is

covered here.. Information covers all information

distribution from, within and out from

the FPA. It includes PPC as well as

PDM.. Human resources covers organizational

issues as well as competence and other

personnel-related questions.. Process includes machine-related issues

like reliability, processing times,

resettings, etc.. Product is an area which includes product

related issues like product design, choice

of materials and aspects that affect the

output of an FPA.

Figure 4 Functional process area definition

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Commonly, more than one area affects the

performance of a manufacturing system. A

complex product design could cause the need

for more resettings than another design would

etc. The possible interactions are numerous.

The influence the FPA has on its

environment is here roughly divided into:

(1) Flexibility. The possibility to produce

entirely new products, to manufacture

different product variants and to be able

to change capacity to meet changes in

demand. This should be considered both

on a long-term basis as well as a

short-term basis.

(2) Speed and swiftness. Included here are lead

times, the possibility of adapting the

production in a short time, operation

times, resetting times and such.

Everything that affects the speed and

swiftness of the system should be

included.

(3) Robustness. The reliability of the system

when it comes to breakdowns,

downtimes, the amount of quality

approved products manufactured etc.

These are non-expected events that affect

the production (including flexibility)

negatively.

(4) Resources needed. The amount of

resources needed to manufacture the

products through the FPA. It could be

measured in money, hours or anything

appropriate.

These four areas are to be divided into

measurable factors for the general use within

a factory.

The strength of the FPA definition is that it

could be applied at different levels of the

manufacturing.

For example, a manufacturing section does,

in turn, consist of different parts. One could

start at factory level and structure in FPAs

down to individual machines if desirable.

Therefore an FPA could consist of lower level

FPAs (Figure 5), which makes it possible to

form a tree structure of the manufacturing

system.

In Figure 6, A and B represent linked FPAs

that form the lowest level within the factory.

Each FPA in the lowest level consists of a row

of individual operations. The B part

resembles the structure of Figure 6.

Each FPA in the lowest level consists of a

row of individual operations. The structure of

the manufacturing system becomes evident.

The material presented in this chapter

forms a base for the intended method, which

aims at finding key properties of a

manufacturing system. The base is far from

complete and is subject to further research.

For example, it should be possible to evaluate

how changes in one area affect the entire

system design. Questions suitable for the

method could be how certain changes in an

assembly process change the robustness of a

department of which the assembly process is a

part, or how changes in materials supply to

an assembly station affects the throughput of

a line.

5. Further development of AIP

Completing research includes finding

solutions to AIP specific production-related

constraints. These constraints are identified

to be necessary to develop according to AIP

demands. Summarising the results presented

in section 3, there is a need for research on:. AIP-specific product module interface

design to be able to create different

product variants by combining different

modules.

Figure 5 FPAs could consist of lower level FPAs. This figure could

describe a cell that consists of three machines

Figure 6 A tree structure formed by FPAs. The lowest and middle levels

of the B part would be equivalent to Figure 5

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. Finding suitable organization forms for a

system designed after the guidelines

provided in the AIP strategy.. Developing flexible and reconfigurable

manufacturing processes. This means

that machinery should be easily

changeable and combinable with each

other to be able to adjust the capacity to

the present order situation.. Developing information systems that are

as changeable as the manufacturing

systems. With information systems are

meant here especially PPC, but also the

availability of product data and other

crucial forms of information.

This does not mean that all other factors

are not needed to be developed further.

What is meant is that the other areas are

useable in their present form or the research

in those areas is taking a direction, also

useful in AIP.

As a parallel development, the theoretical

model will be developed further (Figure 7).

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Figure 7 Future research within the AIP project

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Shortening the designfor assembly processtime for torqueconverter development

Y.J. Lin and

Adam Uhler

1. Introduction

In today’s demanding workplace, customers

are requiring improved designs with shorter

lead times. As technology continues to

provide new tools, the methods that

mechanical engineers use to design products

will continue to change and improve. The

challenge for design engineers is to leverage

the new technology by developing new design

techniques utilizing these new tools

extensively. Tools such as PTC’s Pro/

Engineer offer an engineer the ability to create

solid models that can be used to calculate

mass, inertia, FEA, tool paths, interference,

and kinematics analysis. These calculations

result in a much more robust design and

ultimately shorten the development cycle

through fewer prototypes; however, the

complexity of the new tools requires more

skill and work from the design engineer.

Much of the work needs to be conducted

before the design begins. If a well-developed

plan is not created, design timelines will

actually increase due to the complexity of the

new tools. Design engineers working in

manufacturing industries must look for

methods to decrease the amount of time to

design a product while using the new

technology. One method that offers promise

is modular design of assemblies and the ability

to reuse components.

Three-dimensional CAD systems such as

PTC’s Pro/Engineer represent one of the new

tools available to design engineers. In recent

years, solid modeling has not only changed

the way that engineers design their products,

but also, how companies do business. Due to

the ability of Pro/Engineer to create and

utilize relationships between parts, features,

layouts, etc., different departments within a

design group (tooling, manufacturing,

product development) are becoming more

integrated. With the use of tools like Pro/

Engineer, these new designs can be shared

and prototypes created in very short periods

of time. But, with these new tools comes

increased complexity. Engineers must fully

understand the relationships that are created

in their designs. If care is not taken in laying

out relationships, modifications to a design

will yield extremely different results than

anticipated. It may even be impossible to

The authors

Y.J. Lin is in the Department of Mechanical Engineering,

The University of Akron, Akron, Ohio, USA.

Adam Uhler is a Design Engineer at Luk Inc., Wooster,

Ohio, USA.

Keywords

Design optimization, Mapping, Modeling, Torque

Abstract

By leveraging various designs for assembly and designs for

manufacturing methods, manufacturing industry can apply

solid modeling, or 3D design, to increase profit margins and

decrease the time to market of its product. Specific to torque

converter development, an engineer can utilize a CAD

package and gain all of the advantages of designing in 3D

without the drawback of increased design time. In this paper

we propose a behavioral modeling technique to capture

design intent and utilize the intent maps for obtaining 3D

solid models in a similar amount of time as on a 2D CAD

system, but with the advantage of a life-like final design.

This results in fewer modifications and less inaccuracies

associated with 2D design. A 3D model so generated also

assists in drawing interpretation. In general, using the

proposed techniques will streamline the torque converter

design cycle and move readily towards desired assembly

automation. Torque converter design for assembly is

implemented as an illustrated example.

Electronic access




available at


Research article

The support to this work from Luk Inc. is

gratefully acknowledged.

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DOI 10.1108/01445150210436464

modify a design if improper relationships are

created.

When properly implemented and leveraged,

a 3D modeling package offers several

advantages in the overall development cycle

of a product, such as: 3D visualization,

improved sales presentations, rapid

prototypes, rapid castings, rapid tooling, tool

path creation, FEA, kinematics’ studies, and

assembly interference checks. However, a

corporate-wide effort must be put forth to

realize these gains. In addition, a sound

modeling method must be developed and

incorporated for a smooth running design

cycle.

Even with these advantages, the complexity

of relationships in the 3D system and the

amount of computer processing time

necessary to make modification can cause the

design cycle to increase. In addition, a

standard project will have many variations of

a design before the final design is chosen. In

order for a solid modeling package to be

successful, modifications have to be made

quickly and design modifications have to be

stored.

Design intent within a component is

critical. Each component is dimensioned from

a default coordinate system. As the

component grows, new features can be

dimensioned back to the default coordinate

system or to features that were previously

created. The manner in which the component

is dimensioned will have dramatic effects

when modifications are made to the part. The

designer has to pay special attention to the

dimensioning scheme that is used during the

creation of the part.

Using a solid modeling package is relatively

simple if it is only used to model single parts.

In a real design environment, rarely is a single

component useful because it must interact

without components in an assembly. Before

the design can begin, an abstract idea of the

assembly structure must be considered. This

method of design has been labeled as

‘‘top-down design’’ (PTC, 1998; Koh and

Park, 1996; Koichi et al., 1993; Liesbon,

1999; Mantripragada et al., 1999; Bankq and

Lin, 2001). In other words, top-down design

is a method of designing a product by

specifying top-level design criteria and

passing down these criteria from the top level

of the product’s structure to all the affected

subsystems (PTC, 1998; Koh and Park,

1996; Koichi et al., 1993; Liesbon, 1999;

Mantripragada et al., 1999). In addition,

feature-based design for assembly (DFA)

concepts have become essential issues in

recent research in the design community

(De Fazio et al., 1993, 1999; Eng et al., 1999;

Chuang and O’Grady, 1999; Whitney et al.,

1999). This system embeds the parts’

associativity between the parts in a complex

design machine, which it can automatically,

propagates the dimensional change to the all

related parts globally, in the case of dimension

change in a local part. As product

requirements become more volatile and

exhaustive, and products more highly focused

and tailored, industry requires a different type

of mechanical design automation technology.

The new generation of CAD systems,

behavioral modeling addresses these needs

and promotes the creation of well-designed

products through the synthesis of

requirements, desire functional behavior,

design context and geometry through an

open, extensible environment (PTC, 2000).

Behavioral modeling design system develops

the CAD system one step closer toward the

intelligent modeling design system. It is using

the design intent and design constraints for

generating the all-possible geometric shapes

for a design. An intelligent CAD system is a

target for automating a manufacturing design

system. It contains all the specification and

process information they need to adapt to

their environment. In addition, it applies all

kinds of analyzing and optimizing methods to

model automatically to generate all possible

design alternatives that fulfil the design

intents. In other words, for designing a torque

converter there will be no need to design,

analyze, and optimize the components

individually without considering the

interrelationship effect of the components in a

whole mechanism. However, in order to

create such an intelligent CAD system we

must quantify all interrelationship effects of

the components of the torque converter

during the product development cycle. In

order to embed trade specific functions

efficiently in a CAD system, it is necessary to

understand and formalize the semantics of the

technological objectives concerned, to

determine the mapping relation between

technology and geometry and to clarify the

logical process of the specification of these

technological objectives (Deneux, 1999).

Therefore, this paper is focused on

quantifying the interrelationship effect of the

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torque converter components during the

assembly process.

Understanding how the CAD software will

update models as they are modified and how

relationships are created between models is

essential for building a robust solid model. In

addition, the components in an assembly will

inevitably need to be replaced, deleted,

copied, and moved as the product develops in

its design cycle. Relationships between parts

can tend to make these actions impossible.

Therefore, the assembly structure should be

completely understood and documented

before the design begins. The solid model

must be flexible so that it can grow and

change with the design.

2. Design intent mapping

2.1 Product structure layout with

behavioral modeling concept

Before any 3D modeling can begin on the

torque converter, the project structure must

be carefully considered and laid out. In

considering the project structure, capturing

the design intent of the 3D model can be the

most critical and difficult task of the project

(Paulson, 2000). In a behavioral modeling

sense, the design intent is the manner in

which the model reacts to modifications. It

determines how dimensions and relations are

referenced to features in the design. For

example, if the diameter of the torque

converter doubles, the width may need to

remain half of that value. By laying out the

product structure, solid design intent can be

developed, which will make modifications

easier and faster. Ultimately, the design cycle

is shortened because changes are fast and

easy.

The design input can come from a number

of different sources. This input must be

captured in the design intent through the

solid model. First, the engineer must collect

all of the design input. A beginning point is

aimed at the very basic function of the torque

converter. In a given application, the torque

converter will have a performance

specification that it must meet. Figure 1

shows typical sample performance curves of a

torque converter for design references. This

determines an overall diameter for the torque

converter, at least from a performance

standpoint, and may be considered as one of

the behavioral modeling elements.

Another key factor for the behavioral

modeling elements is the customer envelope.

Due to increasing demands on fuel economy

and weight reduction, the envelope that the

torque converter must fit into decreases. The

envelope is becoming an increasingly

important design criterion and must be

considered in the design intent of the solid

model. Figure 2 illustrates a sample customer

envelope or bell housing schematics.

In accordance with the size of the torque

converter, weight and inertia play an

important role in the design of the torque

converter. Using a 3D model enables the

engineer to calculate and optimize the weight

and inertia of the torque converter. Finally,

structural integrity and manufacturability

round out the behavioral modeling task and

yield the general design criteria for the torque

converter.

2.2 Product development phase for

behavioral modeled components

Throughout the development phase of the

project, the customer is liable to change the

design input. Therefore, it is critical that the

engineer understands the product structure

so that it can be captured properly in the

solid model. Once the solid model is

created, it must be tested to ensure that the

necessary modifications produce the desired

outcome. When captured properly, the

design intent used in a three-dimensional

solid model can be one of the greatest assets

of a parameter driven, three-dimensional,

software package (Braxton, 2000).

However, when the design intent is not

captured properly, it can cause the entire

project to fail. For example, it is possible to

machine prototypes to a given model that

was inadvertently modified due to poor

design intent. The outcome can be months

of lost work and investment.

The first and most basic step of

constructing the product structure is to

identify and list the subsystems in the torque

converter assembly. The sub-assemblies

contained in a torque converter are listed as

follows and shown in Figure 3:. impeller assembly;. reactor assembly;. turbine assembly;. torque converter clutch assembly;. cover assembly

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These components also represent the division

of the product for a modular design approach.

If these sub-assemblies are designed in such a

way that they can be interchanged with other

sub-assemblies of the same type, the possible

torque converter designs multiply. This is an

important concept as the engineer considers

how the sub-assemblies should be constrained

and relate to one another. If fewer constraints

are applied between sub-assemblies, the

sub-assemblies can be replaced much easier.

As such, this saves substantial time for any

necessary modifications.

3. Visual prototyping phase

In this phase of the development cycle, the

CAD-based prototypes of each component

constituting the entire sub-assembly of

functional elements for a torque converter are

to be built. First, the components of each sub-

assembly must be identified. By employing

top-down design concept, at the highest level,

the torque converter has a group of geometric

constraints that are not necessarily

components, but they drive the geometry of

the design. Most of this information will be

stored in the top-level assembly skeleton.

Here the skeleton modeling approach is

introduced (Deueux, 1999). Based on the

proposed behavioral modeling technique, the

following informative elements are considered

and included, namely:. customer envelope;. transmission bell housing;. flex plate;. lug/stud configuration;. transmission pump drive.

3.1 Impeller assembly prototyping

The first component is the impeller assembly.

The impeller assembly is the component that

converts mechanical energy into fluid energy

when the torque converter clutch is

Figure 1 Sample performance curves of a torque converter

Figure 2 Sample customer envelope (bell housing)

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disengaged. When the clutch is engaged, the

impeller directly drives the transmission input

shaft. In addition, the transmission pump is

typically driven by a mechanical connection

to the impeller hub. The impeller consists of

the following components (see Figure 4):

(1) Brazed impeller shell sub-assembly:. finished impeller shell with blade tab

indents;

– stamped impeller shell;

. impeller blades with tabs rolled;

– impeller blade with tabs

unassembled;. impeller core ring with blade tab

slots;

– stamped core ring (optional).

(2) Impeller hub.

The stamped impeller core ring is marked

optional because the manufacturing process

can be combined into the stamping of the

Figure 3 An exploded view of sub-assemblies contained in a torque converter

Figure 4 Virtual prototype of impeller component

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blank based on the curvature of the core

geometry profile. If the core has a shallow

profile, the slot can be stamped into the

blank. This requires added flexibility in the

structure of the core. Each of the semi-

finished parts adds a complication to a

product structure because it needs to be

directly connected to the finished part. When

one of the two parts changes, the other should

change. The two parts must be tied together

for design efficiency and reduction of errors.

3.2 Reactor assembly prototyping

Next, the reactor assembly is axially constrained

to the impeller shell. The reactor redirects fluid

back from the turbine back into the impeller

when the vehicle is launching. This multiplies

the torque of the fluid coupling by recovering

some of the energy still in the fluid after it drives

the turbine. The reactor is constrained radially

by a shaft connected to the bell housing. The

inner race of the reactor must mesh with a

spline on the shaft. The reactor assembly

consists of the following components (see

Figure 5):. machined reactor with outer race

pressed in;

– semi-machined reactor;

– outer race;. rollers;. springs;. inner race;. side plate;. thrust bearing between impeller and

reactor. thrust bearing between reactor and

turbine (optional)

Another optional feature exists in the reactor

assembly. Based on application, the thrust

bearing between the reactor and turbine can

be combined with the side plate as an

integrated thrust washer. This method saves

space and money, but thrust loads may be

extreme for high torque applications. Once

again, the model must accommodate the need

for flexibility.

3.3 Turbine assembly prototyping

The turbine assembly is very similar to the

impeller assembly. The turbine assembly

receives the fluid from the impeller and

converts the fluid energy back to mechanical

energy through a spline tooth connection to

the transmission input shaft. Figure 6 depicts

the virtual prototype of the turbine assembly.

The turbine will also be connected to the

torque converter clutch in a variety of

different methods.

(1) Brazed turbine shell sub-assembly

(optional):. finished turbine shell with blade tab

indents;

– stamped turbine shell;. turbine blades with tabs rolled;

– turbine blade with tabs

unassembled;. turbine core ring with blade tab slots;

– stamped core ring (optional);

(2) Turbine hub, rivets.

(3) Main damper assembly:. springs;

– end caps;. spring retainer.

Figure 5 The reactor assembly prototype

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3.4 Turbine shell assembly prototype

The turbine shell assembly may or may not be

brazed based on the specific application. Also,

depending on the damper configuration, the

main damper assembly may not be contained

in the turbine assembly. In Pro/Engineer, this

can be a difficult task to make flexible because

of the assembly structure. By using modular

design techniques, the turbine assemblies

could be interchanged. In this case, a second

assembly structure could be used as follows

(see Figure 7):. finished turbine shell with blade tab

indents;

– stamped turbine shell;. turbine blades with tabs rolled;

– turbine blade with tabs unassembled;. turbine core ring with blade tab slots;

– stamped core ring (optional);. turbine hub, rivets.

3.5 Torque converter clutch assembly

prototype

The torque converter clutch creates a hard

coupling of the engine and the transmission

using pressure to push a plate against the

cover. The plate has a piece of friction

material bonded to it. There is also a spring,

torsion damper to isolate engine vibrations.

The exploded view of the torque converter

clutch assembly prototype is demonstrated in

Figure 8. The damper can have a variety of

Figure 6 Turbine assembly prototype

Figure 7 Turbine shell assembly prototype

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configurations, which makes it an excellent

candidate for modular design.

Possible configuration:. cover plate;. spring retainer plate;. springs;. end caps;. flange;. piston plate bonded;

– piston plate stamped;. multiple clutch plates, rivets, facing.

The assembly shown in Figure 8 is a triple plate

clutch with an unbonded piston plate. The

spring retainer is part of the clutch in this

particular assembly. This can change as was

shown in the turbine assembly in Figure 6.

The number of varieties of the torque

converter clutch is the most difficult Pro/

Engineer issue with which to deal and to

consider in the behavioral models. The

different configurations can cause the turbine

assembly to change. For example, a spring

retainer could be riveted to the turbine

assembly. The Pro/Engineer assemblies

should match the actual product assembly.

Therefore, modular designs suit the problem

well. If the Pro/Engineer structure of the

torque converter will promote a modular

design in the behavioral model, the two

assemblies can simply be interchanged.

3.6 Torque converter cover assembly

prototype

Finally, the torque converter cover is the last

component in the assembly. The cover

connects the torque converter to the engine. It

also provides a flat friction surface for the

torque converter clutch. The cover also pilots

the converter in the crankshaft of the engine,

and the cover transmits torque through a weld

joint to the impeller. The prototyped

structure is shown in Figure 9 and

components listed as follows:. cover stamping. drive plate assembly (depending on

envelope);

– drive plate;

– studs;

– possibly pilot;. lugs or studs if no drive plate assembly is

used;. pilot (if not in drive plate assembly or not

extruded from the cover).

Again, the components of the assembly can be

found in different assembly structures. This

behavioral modeling concept leads to a modular

design where one cover structure can be

replaced with another as the design changes.

The reason that the product structure is so

important to understand upfront is that

Pro/Engineer does not allow for direct

modifications to the structure. In order to

change the assembly structure, components

must be deleted and reassembled in the proper

sub-assembly. The assembly constraints can be

changed, but a component cannot easily be

moved from one assembly to the next. In

addition, the assembly structure should look the

same as the actual production structure. This

enables the designers as well as the

manufacturers to visualize the live assembly

process of all torque converter components,

sub-assemblies, and final assembly. For

example, the impeller shell, core, and blades

should be assembled in the brazed shell

assembly rather than assembling the

components individually in the top-level

assembly. As a result, physical prototypes of all

components and their assemblages costs,

typically required in a trial-and-error basis, can

be eliminated. It saves design and modification

times tremendously too. By following the

production method, all of the models developed

in the previously mentioned cycle can be

directly made available later on for generating

the two-dimensional working drawings for real

prototyping needs.

4. Behavioral modeling design inputs ofeach assembly

Pro/Engineer allows the designer to relate

features to one another so that the features

Figure 8 An exploded view of a torque converter clutch assembly

prototype

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update as the design input changes (Pieschke,

2000; Uhler, 2000). This represents a huge

timesaving through automation of the design.

However, when the relation is not set up

properly, more time is wasted trying to find

and fix the relation than would have been

spent to make all changes manually. This is

the reason that proper planning is so

important in the initial stages of the design.

In order to properly create relations

between parts, the design inputs need to be

captured for each component. Each assembly

has a different set of design inputs.

One of the most influential inputs driving

the impeller geometry is the fluid dynamic

performance required from the torque

converter. Part of the area that makes up the

fluid coupling is the blade geometry. An

external program called ‘‘Bladegen’’ derives

the blade shape. This program creates a curve

file that is read into Pro/Engineer. This is a

non-associative process, which means that if

the blade changes in ‘‘Bladegen’’, it will not

update in Pro/Engineer. Because of the seam

in the design process, the blade surface must

be trimmed to fit the shell and core in

Pro/Engineer. This will ensure that the

physical parts will fit together in real life. In

addition, the blade has tabs that must fit into

slots in the shell and core. Because of the 3D

geometry of the blade, it is very difficult to

obtain a logical reference point on the blade

to define the geometry. In addition, the

reference point must drive the tab location

and the slot location, but the tab and the slot

must be able to move independent of one

another for manufacturing modifications. It

could be argued that the customer envelope is

the most critical driving constraint because

the converter is useless if it does not fit in the

customer’s space requirement. In actuality,

both must be carefully considered. In

addition, the impeller must provide a thrust-

bearing surface based on the thrust loads in

the converter. Also, the impeller shell must

mate with the torque converter cover, and

provide adequate clearance for the turbine

assembly. Finally, the customer will typically

specify a feature in the impeller hub to drive

the transmission pump.

The reactor is also driven by the

hydrodynamic performance requirements.

The blade geometry is most directly

influenced, but also the hub and rim

diameters. The engine torque will determine

the size of one-way clutch that is required.

The stress level in the one-way clutch can be

calculated from the engine torque. The size of

the one-way clutch has to be modified to limit

the stress levels. In addition, the

circumferential length will determine how

many rollers will fit in the one-way clutch.

The number of rollers will also affect the

stress-level. Also, the customer will

sometimes have a shaft already defined to

which the stator must mate. Finally, thrust

loads will determine the size of thrust bearings

that are used or if a thrust washer can be used

to save cost.

The turbine assembly design input is very

similar to the impeller. The fluid dynamic

performance required from the torque

converter will determine most of the turbine

geometry. The blade for the turbine assembly

is created in the same manner as the impeller,

and therefore, must be trimmed to fit the shell

and core. The turbine assembly will typically

require a hub with a spline connection to the

Figure 9 Torque converter cover sub-assembly prototype

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transmission input shaft. The spline will

typically come from the customer. The spline

size and location is a design requirement. The

turbine assembly must also provide a surface

for thrust bearing or washer in the reactor

assembly. The most common variable in the

turbine assembly will be the torque converter

clutch. In some designs, components of the

torque converter clutch are directly connected

to the turbine assembly through rivets or

weld. The clutch will always be connected to

the turbine assembly in some manner so that

it can transmit torque to the turbine input

shaft, but if a component is an actual part of

the physical assembly, it must be contained in

the assembly structure of the torque

converter.

The driving parameter for the torque

converter clutch is the engine torque. By the

principal of friction and moment, the radius

of the friction material must be large enough

to transmit the engine torque to the

transmission with a specified allowable slip.

The friction coefficient of the paper and the

minimum operating pressure of the

transmission are necessary for this

calculation. The damper in the torque

converter clutch must isolate engine

vibration when the clutch is locked to the

torque converter cover. In addition, the

space requirement is a critical consideration.

These two parameters combine to

determine the type of clutch and the

configuration of the spring package in the

damper. There are many variations for the

clutch, which make a modular design both

difficult and useful.

The cover assembly is the simplest part of

the torque converter, but has many design

inputs. The most basic is that it must mate

to the impeller shell assembly to close the

pressure vessel. The second input is the

connection to the flex-plate given from the

customer. This involves selection of a lug or

stud, a diameter at which the connecter

must be located, and the number of

connectors necessary. In addition, the cover

must provide a friction surface for the torque

converter clutch, and clearance for the

clutch. The cover must have adequate

structural support so that when pressure is

applied to the torque converter, a minimal

amount of elastic and plastic deformation

occurs. Finally, the cover must fit in the

customer’s envelope.

5 Modular design

The term modular is a form of the root word

module. A module is defined as a

standardized unit or changeable part/

component. Therefore, modular design is the

concept of making each component

interchangeable, and thus, multiplying the

possible design combinations exponentially.

The entire design structure that is laid out

in the intent mapping section is intended to

be used with a modular design concept. Each

sub-assembly (module) can be replaced and

used in other modules because there is no

associativity. However, using the simplified

representation of the assembly, the feasibility

of the design can be quickly checked. In this

manner, parts can easily and quickly be

changed, and thus, creating a new torque

converter design in a short period of time.

The chart shown in Figure 10 quickly

reveals that complexity in design is increasing.

As manufacturing capabilities expand,

customers demand a more customized or

tailored product. However, as customization

increases, complexity of the product line also

increases. This tends to make companies

more inefficient. With the modular product

platforms, product assortment complexity

decreased while continuing to meet customer

demands.

This is possible because fewer parts are

needed to make a larger variety of assemblies.

The example depicted in Figure 11 shows

how a truck manufacturer was able to offer a

larger variety of cab assemblies with fewer

parts. Fewer parts results in less design time,

fewer pressing tools, and shorter assembly

time too. All of these factors result in more

products with less cost involved, leading to

higher productivities.

As another example, the following torque

converter (see Figure 12) shows two similar

covers used in a project. Each cover will fit on

the same torque converter, but they have

slightly different features. By using modular

design techniques, all six components of each

cover are completely interchangeable. This

provides multiple cover options, which can be

evaluated, based on a given application.

Finally, Figure 13 illustrates the power of

designing from an assembly (top-down)

perspective. If design practices support a

product range development, the product

range will grow exponentially. If the

product is developed at a component level

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(bottom-up), there is only the growth of one

new product.

6 Conclusions

By leveraging various design for assembly and

design for manufacturing methods,

manufacturing industry can apply solid

modeling, or 3D design, to increase profit

margins and decrease the time to market of its

product. New CAD solid modelers can offer

many advantages over traditional 2D CAD

software, and possibly the greatest advantage

is the engineer can see the component before

it is ever prototyped. This can save both time

and money because the design using these

advanced tools is more accurate and effective.

However, the modeling or design time

Figure 10 Design complexity chart showing the rapid increases in recent decades

Figure 12 Similar torque converter covers, each will fit on the same torque converter, but with slightly different

features

Figure 11 An example of how a truck manufacturer was able to offer a

larger variety of cab assemblies with fewer parts

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required to layout a product increases because

of the complexity of the software. By using

skeletons combined with simplified

representations, the engineer can work in 2D

with the option of 3D instantly. This gives

him the time advantage of 2D with the

realness of the 3D model in addition to the

benefits of FEA capability, kinematics

analysis, tool design, sales presentations, and

rapid prototypes to name just a few.

Each of the design requirements must be

considered as the engineer determines the

proper design intent that is to be captured by

the 3D model. By identifying each input and

function of the sub-components in the

assembly, a plan can be made to drive the

information from a logical source in the context

of a CAD environment. Applying the proposed

technique ensured that each component in the

model was current with the latest design

specification. The method described in this

paper has proved to be extremely effective for

torque converter development. For future

research and development, these techniques

will continue to expand and improve as

software and computers update.

References

Banka, N. and Lin, Y.J. (2001), ‘‘Mechanical design forassembly of a 4-dof robotic arm utilizing atop-down concept’’, Robotica, in review.

Braxton, T. (2000), ‘‘Mapping your good intentions’’, PROFiles, Vol. 4 No. 12.

Chuang, W. and O’Grady, P. (1999), ‘‘Assembly processvisualization in feature based design for assembly’’,International Journal of Agile Management Systems,Vol.1 No.3, pp. 177-89.

De Fazio et al. (1993), ‘‘Prototype of feature-based designfor assembly’’, J. Mechanical Design, Transactions ofthe ASME, Vol. 115 No. 4, pp. 723-34.

De Fazio, T.L., Rhee, S.J., Whitney and Daniel E. (1999),‘‘Design specific approach to design for assembly(DFA) for complex mechanical assemblies’’, IEEETransactions on Robotics and Automation, Vol. 15No. 5, pp. 869-81.

Deneux, D. (1999), ‘‘Introduction to assembly features: anillustrated synthesis methodology’’, Journal ofIntelligent Manufacturing, Vol. 10, pp. 29-39.

Eng, T., Ling, Z., Olson, W. and McLean, C. (1999),‘‘Feature-based assembly modeling and sequencegeneration’’, Computers and Industrial Engineering,Vol. 36 No.1, pp. 17-33.

Koh, B.K and Park, G.J. (1996), ‘‘Design of automobileexhaust system using top-down approach designmethodology’’, Int. J. of Vehicle Design, Vol. 17No. 3, pp. 276-94.

Koichi, K., Hiromasa, S., Hidetoshi, A. and Fumihiko, K.(1993), ‘‘A product modeling system for top-downdesign of machine assembly with kinematicmotion’’, Robotics & Computer IntegratedManufacturing, Vol. 10 No. 1/2, pp. 49-55.

Liesbon, S.H. (1999), ‘‘Developing CAE tools for top-downdesign of complex systems’’, EDN, Vol. 33, March,pp. 130-6.

Mantripragada, R., Adams, J.D., Rhee, S.H. and Whitney,D.E. (1999), ‘‘Integrated tools for top-downassembly design and analysis’’, Proceedings of the1999 IEEE International Conference on Robotics &Automation, Detroit, MI, May.

Paulson, D.W. (2000), ‘‘Capturing design intent withlayouts’’, PRO files, Vol. 4 No. 3.

Pieschke, K, ‘‘Pro/Engineer’s secret weapon – featurerelations’’, PRO Files, Vol. 5 No. 2.

PTC (1998), Top-Down Design Task Guide2, ParametricTechnology Corp., Waltham, MA, DOC-U0169P-EN-200.

PTC (2000), Consistent Innovation with BehavioralModeling, Parametric Technology Corp., Waltham,MA, pp. 1-16.

Uhler, A. (2000), ‘‘Utilizing various methods to shortenPro/Engineer design time for torque converterdevelopment’’, Master’s research, The University ofAkron, Akron, OH, Spring.

Whitney, D.E., Mantripragada, R., Adams, J.D. and Rhee,S.J. (1999), ‘‘Designing assemblies’’, Research inEngineering Design – Theory, Applications, andConcurrent Engineering, Vol. 11 No. 4, pp. 229-53.

Figure 13 The schematics showing the power of designing from an assembly (top-down) perspective

259



Assembly Automation

Volume 22 . Number 3 . 2002 . 248–259

Geometric variationprediction inautomotive assembling

C. Xiong, Y. Rong

R.P. Koganti, M.J. Zaluzec and

N. Wang

1. Introduction

Geometric variations are inherent in any

manufacturing and assembly process and

cause small deviations in parts from the

nominal geometry. The deviations affect

position, orientation, and other behaviors of

parts in an assembly. Moreover, these

deviations propagate and accumulate as parts

are assembled and can quickly drive assembly

geometry out of specifications, which

consequently causes various functional

failures and uncertainties of mechanical

products. Generally, product quality is

guaranteed by specifying ranges of allowable

deviations of a set of key assembly features as

assembly tolerances. The geometry variations

can seldom be eliminated in assembly

processes. To remain competitive, reduce

manufacturing time and costs of products, it

is necessary to predict and control the

variations in assembling. Once the geometry

variations exceed the tolerance specifications,

the factors affecting the geometry variations

must be investigated and effective measures of

controlling assembly processes need to be

provided.

In the past years, a lot of research work has

been done in the area of assembly tolerance

stack-up, including the constraint based

assembly analysis (Lee and Gossard, 1985;

Lee and Andrews, 1985) tolerance chain

analysis (Chase and Greenwood, 1988), sheet

metal deformation (Jack et al., 2000; Charles

and Jack, 1997; Ceglarek, 1998) fixturing

effect within a single assembly setup (Cai et

al., 1996; Jin and Shi, 2000), assembly

accuracy (Lee and Yu, 2000), optimum

tolerance allocation in assembly (Ngoi and

Min, 1999; Wei, 1997), assemblability

evaluation based on tolerance propagation

(Lee and Yi, 1995; Inui et al., 1996;

Sanderson, 1999; Li and Roy, 2001)), and

tolerance representations (Whitney et al.,

1994, 1999; Teissandier et al., 1999).

Variation stack-up analysis is a common

method for evaluating the conformity of

actual geometrical elements, surfaces, or lines

to their nominal size or shape. A graphical

approach was presented as the ‘‘Catena’’

method to perform assembly tolerance stack

analysis for form control (Ngoi et al., 1999a),

and applied the coordinate tolerance system

to tolerance stack analysis involving position

tolerance for individual parts (Ngoi et al.,

The authors

C. Xiong is at the Department of Mechanical Engineering,Worcester Polytechnic Institute, Worcester, Massaschusetts,USA and the School of Mechanical Science, HuazhongUniversity of Science and Technology, Wuhan, PR China.Y. Rong is at the Department of Mechanical Engineering,Worcester Polytechnic Institute, Worcester, Massaschusetts,USA.R.P. Koganti, M J. Zaluzec and N. Wang are at theManufacturing Systems Department, Ford ResearchLaboratory, Ford Motor Company, Dearborn, Michigan, USA.

Keywords

Assembly, Statistical process control, Quality control,Predictive techniques, Error estimation,Automotive industry

Abstract

This paper develops the statistical error analysis model forassembling, to derive measures of controlling the geometricvariations in assembly with multiple assembly stations, andto provide a statistical tolerance prediction/distributiontoolkit integrated with CAD system for responding quickly tomarket opportunities with reduced manufacturing costs andimproved quality. First the homogeneous transformation isused to describe the location and orientation of assemblyfeatures, parts and other related surfaces. The desiredlocation and orientation, and the related fixturingconfiguration (including locator position and orientation) areautomatically extracted from CAD models. The location andorientation errors are represented with differentialtransformations. The statistical error prediction model isformulated and the related algorithms integrated with theCAD system so that the complex geometric information canbe directly accessed. In the prediction model, themanufacturing process (joining) error, induced by heatdeformation in welding, is taken into account.

Electronic access

The research register for this journal is available athttp://www.emeraldinsight.com/researchregisters

The current issue and full text archive of this journal isavailable athttp://www.emeraldinsight.com/0144-5154.htm

Research article

260

Assembly Automation

Volume 22 . Number 3 . 2002 . pp. 260–269


DOI 10.1108/01445150210436473

1999b). Most of the work mainly focuses on

single assembly station for rigid parts.

In recent years, some researchers have

studied the statistical error analysis during

assembling (Lee and Yi, 1995; Whitney et al.,

1994), including compliant part deformation

prediction (Hu, 1997; Soman, 1996). The

Monte Carlo simulation (Shan et al., 1999)

and the tuning parameter design method

(McAdams and Wood, 2000) are often used

in statistical tolerance analysis. To predict

and control variation propagation, the

assembly sequence of mechanical assemblies

was modeled as a multistage linear dynamic

system (Mantripragada and Whitney, 1999).

Almost all the prediction models are linear.

However, there exists nonlinear coupling and

stack-up among all kinds of errors during

assembling because multiple fixtures are used

in each subassembly station. In fact, the

design and planning of locator schemes

(Zhang et al., 2001; Xiong et al., 1999) are the

challenges that are very critical for assembly.

Thus the linear prediction models cannot be

used to describe the assembly error

propagation from one to another subassembly

station. In addition, up to now, there has been

no statistical error analysis tool reported,

which is integrated with CAD system and

applicable for multiple assembly stations with

multiple fixtures.

In order to describe the characteristics of

coupling, stack-up, and propagation of

assembly errors during assembling for

multiple subassembly stations with multiple

fixtures, this paper proposes a systematic

approach to the assembly geometry variation

prediction. This paper is organized as follows.

Section 2 formulates the prediction problem

of assembly errors. Section 3 develops the

assembly errors’ representation and the

dimensional variation prediction algorithms.

Section 4 integrates the prediction

algorithms with the I-DEAS system. Section

5 gives a case study to verify the proposed

algorithms. Finally, conclusions are presented

in Section 6.

2. Formulation of problem

A product assembly system is a multileveled

hierarchical system, in which several parts are

joined together to form a subassembly and in

turn becomes a part to the next level of

assembly. Geometry variation in the final

assembly is accumulated as several parts are

assembled at each level of the system.

Moreover, the geometry variations will

propagate from one level subassembly station

to the next station. Prediction and control of

the geometry variations are essential to

retaining competitiveness in manufacturing

because excessive variations directly affect

product quality, time-to-market, and product

development cost. In every subassembly

station, the product geometry variations

depend on geometry errors, fixture location

errors, process error (heat induced

deformation in welding), and assembly

sequences. When multiple fixtures are used in

assembly stations, the geometry errors may be

coupled together in the error propagation,

which causes the non-linearity in the

tolerance stack-up model. Also, how to

optimize assembly sequences is one of the

problems to be solved in the assembly error

synthesis. To predict the geometry variations,

it is necessary to develop an analytical model

of the error coupling and stack-up in each

sub-assembly station as well as in the

propagation from one sub-assembly station to

another. Especially, the process errors such as

heat deformation need to be considered in the

analysis model.

The error stack-up and propagation during

assembly are shown in Figure 1, where

�mi � <6�1; �li �<6�1 and �wi �<6�1, are the

manufacturing error (geometric error),

locator error of fixtures and process error of

the ith part respectively. The problem of the

geometry variation prediction can be

described as: given the assembly setup

specifications, i.e. the manufacturing errors

�mi ;, locator position and orientation,

fixture’s locator errors �li;, and process errors

�wi ;, to calculate the variation of featureQk in

final assembly of product, in a statistical way,

where Qk can be described as:

Qk ¼ fk �m �l �wð Þj j ¼ 1 � � � nj� �

;

k ¼ 1 � � � K ð1Þ

In equation (1), j denotes the number of sub-

assembly station, and Qk is the kth element of

a set of key assembly requirements Q.

Equation 1 implies that assembly errors are

the nonlinear coupling and stack-up of all

kinds of errors such as�m,�l , and�w in each

subassembly station.

In addition, different fixture configurations

result in different fixturing errors. Fixturing

261

Geometric variation prediction in automotive assembling

C. Xiong, Y. Rong, R.P. Koganti, M.J. Zaluzec and N. Wang

Assembly Automation

Volume 22 . Number 3 . 2002 . 260–269

�l ¼ ð�plx �ply �plz ��lx ��ly ��lzÞT errors

depend on the locators’ positions rwi, 2 <3x1

and (i = 1, � � � ; m) and the normal position

errors �rl = (�rl1 � � � �rlm)T 2 <m�1; the

fixture locating errors can be written as

(Xiong et al., 1999; Xiong et al.

(forthcoming),

�l ¼ Wþ � L ��rl ð2Þ

where W+ = (WTW)–1 WT 2 <6�3m is the

general inverse of the fixturing matrix

W2 <3m�6, and

W ¼I3�3� G

WRrw1

� ��

..

.

I3�3� GWRrwm

� ��

264

3753m�6

;

L ¼ diag n1 � � �nmð Þ 2 <3m�m;

I363 is an identity matrix, GW

R is the

orientation transformation matrix of the part

frame with respect to the global coordinate

frame, Ni 2 <3�1 (i = 1, � � �, m) is the unit

normal vectors at each locator. How to plan

fixture configurations so that the fixturing

errors can be minimized is another problem to

be solved in the assembly error synthesis.

3. Statistical tolerance analysis anddimensional variation prediction

3.1 Assembly tolerance representation

Assume that the position and orientation of a

coordinate frame are represented as

p ¼ ðpx py pz �x �y �zÞT , then the

corresponding homogeneous transformation

matrix can be written as:

TðpÞ ¼

pxRð�x; �y; �zÞ py

pz01�3 1

2664

3775 ð3Þ

where Rð�x; �y; �zÞ 2 <3x3Þ is the orientation

matrix of the coordinate frame.

Assume that the position and orientation

errors of the coordinate frame are represented

as �p ¼ ð�px �py �pz ��x ��y �zÞT , thecorresponding differential transformation

matrix can be expressed as:

T �pð Þ ¼

1 ��z ��y �px��z 1 ��x �py��y ��x 1 �pz0 0 0 1

2664

3775ð4Þ

To analyze assembly tolerances, we use

homogeneous transformation to describe the

location and orientation of assembly features,

parts and other related surfaces. The location

and orientation errors are represented with

differential transformation, as shown in

Figure 2, the desired and actual location and

orientation of assembly feature j (target) with

respect to i (datum) can be described by the

location and orientation of related

coordinated frames.

In Figure 2, {Datum_desire} is the desire

coordinate frame of the feature i without

errors. {Datum_actual} is the actual

coordinate frame of the feature i, which

deviated from the desired coordinate frame

due to the part manufacturing error, fixture

locating error and welding error.

{Target_desire} is the desire coordinate

frame of the feature j without errors.

{Target_actual} is the actual coordinate

frame of the feature j, which deviated from the

desired coordinate frame due to the part

manufacturing error, fixture locating error

and welding error. If {Datum_actual} were

regarded as the desire coordinate frame of the

feature i, then {Target_desire_virtual} would

be regarded as the desire coordinate frame of

the feature j. In all coordinate frames, the

z-axes coincide with the outer normal vectors

of the feature surfaces or axes.

Let Dd

TdT and Da

TaT be the homogeneous

transformation matrices of the desire and

Figure 1 Error stack-up and propagation during assembly

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Assembly Automation

Volume 22 . Number 3 . 2002 . 260–269

actual target features with respect to the

desire and actual datum features respectively,

then:

Tdv

TaT ¼ Tdv

DaT � Da

TaT ð5Þ

Since

Tdv

DaT ¼ Td

DdT ð6Þ

Equation (5) can be rewritten as:

Tdv

TaT ¼ Td

DdT � Da

TaT ð7Þ

where Td�

TaTðTd�

DaT) are the homogeneous

transformation matrices of the frame

{Target_actual} ({Datum_actual} ) with

respect to the frame {Target_desire_virtual} .

The matrix Dd

TdT can be calculated using the

related points’ position information obtained

from CAD model. Using the matrix Dd

TdT , we

can obtain the desired position and

orientation q = (px py pz �x �y �zÞT of the

target feature with respect to the datum

feature. The matrix Da

TaT is related to the

geometric errors �m of parts and the process

errors such as fixture locating errors �l and

process errors�w during assembling, it can be

written as:

Da

TaT ¼ Da

DdT �m þ�lð Þ � Dd

TdT � Td

TaT �mð

þ�l þ�wÞ ¼ Dd

DaT � �m þ�lð Þ½ ��

Dd

TdT � Td

TaT �m þ�l þ�wð Þ ð8Þ

Thus, substituting equation (8) into

equation (7) yields:

Tdv

TaT ¼ Td

DdT � Dd

DaT � �m þ�lð Þ½ � � Dd

TdT � Td

TaT

�m þ�l þ�wð Þ ð9Þ

From equation (9), it can be seen that there

are error variables coupled in the

transformation matrices, which results in the

non-linearity of the model.

3.2 Dimensional variation prediction

modeling

3.2.1 Position and orientation tolerance

prediction

Using equation (8), we can calculate the

errors �q¼ ð�px �py �pz ��y ��2ÞT of the

position and orientation of the target feature

with respect to the datum feature, which is the

accumulated errors due to manufacturing

Figure 2 Position and orientation of target feature with respect to datum feature

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errors, fixture locating errors and process

errors in current sub-assembly station. After

being assembled in current sub-assembly

station, the errors �q become manufacturing

errors �m if the assembled part in current

station needs to be assembled with other parts

in the next station. This implies that

manufacturing errors, fixture locating errors,

and process errors propagate from one sub-

assembly station to another station during

assembling.

The tolerance of the target feature with

respect to the datum is the deviations of

z-coordinates of all characteristic points of the

actual target surface in the coordinate frame

{Target_desire_virtual} .

Assuming that there exists a point pai

(homogeneous point) in the frame

{Target_actual} , then, by using equation

(7), the point homogeneous coordinates can

be obtained in the frame {Target_desire_

virtual} is as follows:

pd�i ¼ Da

Td

TðqÞ� ��1

:Da

TaT ðqþ�qÞ:pa

i ð10Þ

From equation (10), z-coordinate zi of the

ith point pi is obtained and zi is a function of

the errors �q. The error variables �q may

be random in tolerance design and analysis.

If it is normally distributed, thus the

deviation �zi of the z-coordinate can be

described as:

�zi ¼

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi@zi@px

��px

� �2

þ � � � þ @zi@�z

��z

� �2s

;

i ¼ 1; � � � ; n ð11Þ

where #zi#px

, � � �, and #zi#�z, are the partial

differential of the function ziwith respect to

the variables px; � � �, and �z respectively.

The actual position and orientation

tolerance can be written as:

Tol ¼ max �zif g þmin �zif g ð12Þ

It should be noted that this method is directly

applicable for orientation tolerance

specifications and also applicable for other

types of tolerances (Kang, 2001).

Furthermore, if the error distribution is other

than normal distribution, the Monte Carlo

simulation method can be used.

Thus, we obtain an algorithm to predict the

position and orientation tolerance in the view

of statistics as follows:

Algorithm 1

. Step 1. Select assembly target feature and

datum feature.. Step 2. Calculate Td

DdT :

. Step 3. Input locator errors of fixtures.

. Step 4. Calculate fixture locating errors

using equation (2).. Step 5. Input geometric errors of parts to

be assembled, and process errors.. Step 6. Calculate Da

TaT using equation (8).

. Step 7. Calculate position and orientation

errors of target feature with respect to

datum feature.. Step 8. If continue to assemble, repeat

steps 1-7 for next assembly station.. Step 9. Calculate actual position and

orientation tolerance to be predicted

using equation (12).

3.2.2 Position error prediction of points

in space

After the matrix Da

TaT is obtained, i.e. the

homogeneous transformation matrix of the

frame {Target_actual} with respect to the

frame {Target_desire_virtual} is obtained as

a function of the position and orientation

errors �q, we can calculate the homogeneous

coordinates pj = ðxj yj zj 1ÞTof any point

paj ¼ ðxaj yaj zaj 1ÞT in the target feature, i.e.

xjyjzj1

0BB@

1CCA ¼ Tdv

TaT �qð Þ �

xajyajzaj1

0BB@

1CCA ð13Þ

equation (13) can be rewritten as:

xj ¼ fj1 �px � � � ��zð Þyj ¼ fj2 �px � � � ��zð Þzj ¼ fj3 �px � � � ��zð Þ

ð14Þ

Thus, the position errors of the point

paj(j = 1) can be written as:

�xj ¼

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi@fj1@px

��px

� �2

þ � � � þ @fj1@�z

��z

� �2s

�yj ¼


��px

� �2

þ � � � þ @fj2@�z

��z

� �2s

�zj ¼


��px

� �2

þ � � � þ @fj3@�z

��z

� �2s

ð15Þ

where@fj�@px

; � � �, and @fj�@�z

are the partial

differentiations of the function fj6 with

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Volume 22 . Number 3 . 2002 . 260–269

respect to the variables px, . . ., and �2respectively.

Thus, we obtain another algorithm to

predict the position errors of points in the

view of statistics as follows:

Algorithm 2

. Step 1. Select assembly target feature and

datum feature.. Step 2. Calculate Td

DdT.

. Step 3. Input locator errors of fixtures.

. Step 4. Calculate fixture locating errors

using equation (2).. Step 5. Input geometric errors of parts to

be assembled, and process errors in

assembly.. Step 6. Calculate Ta

DaT using equation (8).

. Step 7. Calculate position and orientation

errors of target feature with respect to

datum feature.. Step 8. If continue to assemble, repeat

steps 1-7 for next assembly station.. Step 9. Calculate actual position errors to

be predicted using equation (15).

4. Integrated prediction algorithms withCAD system

An assembly analysis system should include

three parts, assembly information resource,

key geometry variation prediction algorithms,

and assembly tolerance distribution strategy.

The assembly information resource provides

the geometric and tolerance information about

the parts, setup and fixture configuration,

assembly sequence, and process information.

The algorithms of predicting geometry

variations should be able to deal with the

characteristics of multiple fixture locating

errors, coupling effects of different errors, and

stack-up and propagation of all kinds of errors

in multiple subassembly stations. At the same

time, the tolerance distribution strategies

should be developed aiming at such

characteristics. Then the effective strategies

can be used to improve the assembly sequence

planning, the configuration of fixture locators,

and the assembly processes. Geometry

variation prediction algorithms and tolerance

distribution strategies are inter-dependent.

Developing the integrated geometry variation

prediction and control approach is the kernel

to improve further assembly quality control.

The framework of the system is shown in

Figure 3.

First the desired location and orientation of

parts in a product and their geometric errors

are automatically extracted from the product

CAD model with tolerance information.

Once the initial assembly sequence and

process are identified, an initial assembly

process graph and the datum flow chain

graphs of subassemblies can be constructed.

Based on the geometric error information, the

results of fixture locating error analysis,

process and connection error analyses, the

assembly error coupling and stack-up can be

described. The assembly error propagation in

multiple subassembly stations is followed to

provide information for the geometry

variation prediction. Then with the

probability distributions of all kinds of errors,

the dimensional variation prediction

algorithms can be applied to judge the key

assembly tolerance requirements. Once the

unsatisfied is identified, the assembly

tolerance distribution strategies must be

presented to improve the assembly sequence

and tolerance distribution as well as the

fixture design so that the assembly quality

control is implemented.

5. Case study

To verify the proposed algorithms of

predicting geometry variations in assembly,

two case studies are conducted for analyzing

assembly tolerances.

Case 1

In this case, two parts are welded together

into a ‘‘T-node’’ with two fixtures. Each

fixture constrains one part completely. The

tolerances of the assembly fixture pin

positions are + 0.125mm. The extrusion

surface tolerances of parts are + 0.250 mm,

and the extrusion end cut tolerances are +0.500mm. We need to predict position errors

of ten points on the part ‘‘T-node’’ as shown

in Figure 4. To predict position errors,

algorithm 2 is applied. First, the information

of geometric features for each setup, such as

the assembly target features and datum

features, the locator errors of each fixture, and

the geometric errors of parts to be assembled,

is input into the system by using the CAD

interface. Once all inputs are set, the system

will use the embedded algorithm to calculate

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Assembly Automation

Volume 22 . Number 3 . 2002 . 260–269

the corresponding position errors. Before

welding, the part errors are caused by part

manufacturing errors and fixturing datum

variation. Similarly, to predict position errors

after welding, the heat induced errors during

welding are input into the system. Using the

same algorithm embedded in the system, we

can obtain the corresponding position errors.

Because of the influence of three types of

factors, namely, the locator errors of fixtures,

the geometric errors of parts, and the heat

induced errors during welding, the final

position errors after welding are larger than

the ones before welding. In this case, the

number of measurement samples is 40. The

prediction results are consistent with the

measured results. Table I gives the predicted

position tolerances.

Figure 3 Integrated dimensional variation prediction and control framework

Figure 4 T-node module

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Case 2

In the second case, a front end module in the

development work in body structure is

studied, as shown in Figure 5. There are 20

parts to be welded within five subassembly

stations. In the first three stations, each

station contains two fixtures to constrain the

corresponding part to be assembled through

welding. In the later two stations, there are

more than two fixtures in each station. The

tolerances of the assembly fixture pin

positions are + 0.125mm. The extrusion

surface tolerances of parts are + 0.250mm,

and the extrusion end cut tolerances are

+ 0.500mm. The design tolerances of the

distance along x- and y-axis directions are

+ 0.4mm and + 0.3mm respectively. We

need to predict distance errors between the

left and right shock tower holes during

welding.

By using algorithm 1, the prediction errors

were obtained along x- and y-axis directions

as, before welding, + 0.363mm and

+ 0.4665mm respectively. The prediction

errors after welding are + 0.373mm and

+ 0.5135mm respectively.

From the prediction results, it can be seen

that the distance errors after welding are

larger than before welding because of heat

induced deformation during welding. The

prediction errors are out of the design

tolerance specifications. Assembly errors

depend not only on the geometric errors,

fixture locating errors and welding errors, but

also on the assembly sequences. Thus, the

planning of the assembly sequences is an

alternative and effective measure for product

quality control.

6. Conclusions

In this paper, the characteristics of error

coupling, stackup and propagation within

multiple subassembly stations are modeled

and analyzed. To develop an assembly error

prediction model, homogeneous

transformation matrices are used to represent

the location and orientation of assembly

features, parts and other related surfaces, and

use the differential transformation to describe

the location and orientation errors. Two

statistical prediction algorithms are presented.

One is for predicting the position and

orientation tolerance of any parts in the

assembly and the other is for predicting the

Table I T-node tolerance

Nominal coordinates Coordinate errors (prediction tolerances)

Point no. x y z dx dy dz

Before welding (without heat error)

1 –27.54 37.52 25.40 0.06 0.25 0.26 Z

2 233.79 37.52 25.40 0.06 0.25 0.26 Z

3 235.60 75.05 0.41 0.25 0.26 0.06 Y

4 –32.78 75.05 0.33 0.25 0.26 0.06 Y

5 96.81 75.05 59.08 0.15 0.33 0.11 Y

6 100.47 75.05 309.29 0.15 0.33 0.11 Y

7 74.60 42.27 203.63 0.27 0.10 0.07 X

8 125.40 35.37 186.90 0.29 0.09 0.07 X

9 99.91 48.83 –25.40 0.25 0.06 0.26 Z

10 105.10 75.05 5.32 0.25 0.26 0.06 Y

After welding (with heat error)

1 –27.54 37.52 25.40 0.058 0.252 0.290 Z

2 233.79 37.52 25.40 0.058 0.252 0.290 Z

3 235.60 75.05 0.41 0.252 0.291 0.058 Y

4 –32.78 75.05 0.33 0.252 0.291 0.058 Y

5 96.81 75.05 59.08 0.150 0.580 0.107 Y

6 100.47 75.05 309.29 0.154 0.588 0.108 Y

7 74.60 42.27 203.63 0.556 0.100 0.065 X

8 125.40 35.37 186.90 0.567 0.092 0.067 X

9 99.91 48.83 –25.40 0.253 0.058 0.290 Z

10 105.10 75.05 5.32 0.252 0.291 0.058 Y

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Assembly Automation

Volume 22 . Number 3 . 2002 . 260–269

position errors of any points in related parts.

The case studies were conducted to verify the

two prediction algorithms. The obtained

results showed that the algorithms are

effective and reliable.

The proposed geometry variation

prediction methods have taken into account

not only the geometric errors, but also process

errors such as multiple fixture locating errors

and welding errors. Moreover, the proposed

methods are integrated with a CAD system,

which means the methods are more practical

and easy to apply.

References

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metal fixturing: principles, algorithms, and

simulation’’, Journal of Manufacturing Science and

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evaluation of adaptive sheet metal assembly

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pp. 17-22.Chase, K.W. and Greenwood, W.H. (1998), ‘‘Design issues

in mechanical tolerance analysis’’, Manufacturing

Review, Vol. 1 No. 1.

Hu, S.J. (1997), ‘‘Stream-of-variation theory forautomotive body assembly’’, Annals of the CIRP,Vol. 46 No. 1, pp. 1-6.

Hu, S.J., Long, Y. and Camelio, J. (2000), ‘‘Variationanalysis for compliant assembly’’, Proceedings ofthe ASME Manufacturing in Engineering Division,pp. 31-7.

Inui, M., Miura, M. and Kimura, F. (1996), ‘‘Positioningconditions of parts with tolerances in an assembly’’,IEEE International Conference on Robotics andAutomation, pp. 2202-7.

Jin, J. and Shi, J. (2000), ‘‘State space modeling of sheetmetal assembly for dimensional control’’, Journal ofManufacturing Science and Engineering.

Kang, Y. (2001), ‘‘Computer-aided fixture designverification’’, PhD dissertation, WorcesterPolytechnic Institute, Worcester, MA.

Lee, K. and Andrews, G. (1985), ‘‘Inference of thepositions of components in an assembly: part 2’’,Computer-Aided Design, Vol. 17 No. 1, pp. 20-4.

Lee, K. and Gossard, D.C. (1985), ‘‘A hierarchical datastructure for representing assemblies: part 1’’,Computer-Aided Design, Vol. 17 No. 1, pp. 15-19.

Lee, N.K.S. and Yu, G.H. (2000), ‘‘Effect of mechanicalalignment system on assembly accuracy’’,Proceedings of the ASME Manufacturing inEngineering Division, pp. 47-53.

Lee, S. and Yi, C. (1995a), ‘‘Assemblability evaluationbased on tolerance propagation’’, IEEE InternationalConference on Robotics and Automation,pp. 1593-8.

Lee, S. and Yi, C. (1995b), ‘‘Evaluation of assemblabilitybased on statistical analysis of tolerance

Figure 5 Front end module

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propagation’’, IEEE International Conference onRobotics and Automation, pp. 256-61.

Li, B. and Roy, U. (2001), ‘‘Positioning of toleranced partsin a 2D polygonal assembly and its use in toleranceanalysis’’, IEEE Transactions on Robotics andAutomation, Vol. 17 No. 3, pp. 357-60.

Liu, S.C. and Hu, S.J. (1997), ‘‘Variation simulation fordeformable sheet metal assemblies using finiteelement methods’’, Transactions of the ASME –Journal of Manufacturing Science and Engineering,Vol. 119, pp. 368-74.

McAdams, D.A. and Wood, K.L. (2000), ‘‘Tuningparameter tolerance design: foundations, methods,and measures’’, Research in Engineering Design,Vol. 12, pp. 152-62.

Mantripragada, R. and Whitney, D. (1999), ‘‘Modeling andcontrolling variation propagation in mechanicalassemblier using state transition models’’, IEEETrans. on Robotics and Automation, Vol. 15 No. 1,pp. 124-40.

Ngoi, B.K.A. and Min, O.J. (1999), ‘‘Optimum toleranceallocation in assembly’’, Int. J. Adv. Manuf Technol.,Vol. 15, pp. 660-5.

Ngoi, B.K.A., Lim, L.E.N., Ang, P.S. and Ong, A.S. (1999a),‘‘Assembly tolerance stack analysis for geometriccharacteristics in form control – the ‘Catena’method’’, Int. J. Adv. Manuf Technol., Vol. 15,pp. 292-8.

Ngoi, B.K.A., Lim, L.E.N., Ong, A.S. and Lim, B.H. (1999b),‘‘Applying the coordinate tolerance system totolerance stack analysis involving positiontolerance’’, Int. J. Adv. Manuf Technol., Vol. 15,pp. 404-8.

Sanderson, A.C. (1999), ‘‘Assemblability based onmaximum likelihood configuration of tolerances’’,

IEEE Trans. on Robotics and Automation, Vol. 15No. 3, pp. 568-72.

Shan, A., Roth, R.N. and Wilson, R.J. (1999), ‘‘A newapproach to statistical geometrical toleranceanalysis’’, Int. J. Adv. Manuf Technol., Vol. 15,pp. 222-30.

Soman, N.A. (1996), ‘‘A model of the assembly ofcompliant parts’’, Ph.D. dissertation, MassachusettsInstitute of Technology, Cambridge, MA.

Teissandier, D., Couetard, Y., Gerard, A. (1999), ‘‘Acomputer-aided tolerancing model: proportionedassembly clearance volume’’, Computer AidedDesign, Vol. 31, pp. 805-17.

Wei, C.C. (1997), ‘‘Allocating tolerances to minimize costof nonconforming assembly’’, AssemblyAutomation, Vol. 17 No. 4, pp. 303-6.

Whitney, D E., Gilbert, O. L. and Jastrzebski, M. (1994),‘‘Representation of geometric variations usingmatrix transforms for statistical tolerance analysis inassemblies’’, Research in Engineering Design, Vol. 6,pp. 191-210.

Whitney, D.E., Mantripragada, R., Adams,J.D. and Rhee,S.J. (1999), ‘‘Designing assemblies’’, Research inEngineering Design, Vol. 11, pp. 229-53.

Xiong, C.H., Li, Y.F., Ding, H. and Xiong, Y.L. (1999), ‘‘Ondynamic stability of grasping’’, International Journalof Robotics Research, Vol. 18 No. 9.

Xiong, C.H., Li, Y.F., Rong, Y. and Xiong, Y.L. (n.d.),‘‘Qualitative analysis and quantitative evaluation offixturing’’, International Journal Robotics andComputer Integrated Manufacturing (forthcoming)

Zhang, Y., Hu, W., Kang, Y., Rong, Y. and Yen, D.W.(2001), ‘‘Locating error analysis and toleranceassignment for computer-aided fixture design’’,International Journal of Production Research.

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Dimensional variationsduring Airbus wingassembly

M. Saadat and

C. Cretin

Introduction

Very large components are more prone than

others to variations of shape and dimension.

This causes many problems in the civil

aircraft manufacturing industry, where,

despite the size of the components, the

tolerances for manufacturing and assembly

are kept very tight. The problems associated

with large components’ geometric variation at

the time of assembly can be inherited during

any of the preceding processes including

initial machining of rough materials to various

sub-assemblies. Further, at the assembly

stage, it is highly desirable to introduce

automation through the implementation of a

flexible jig structure. This would involve

carrying out activities such as component

handling, accurate positioning and part

fastening such as riveting, through the use of

sensors, robots and other automated

actuators. It is therefore a prerequisite of any

automation attempt to determine the sources

and amount of dimensional variations of

components that are currently being

experienced during the manual assembly

stage. However, defining which variation was

caused by which process, and on which part,

can be very tedious in a complex assembly

system that involves a large number of parts

(Ligget, 1993). Some of the most obvious

causes of variation are related to the

manufacturing processes, such as forming,

machining, fastening, but also to the

environment, such as temperature and time,

or the design due to the tolerance band.

The study of the dimensional variations

occurring in assembly starts with their

quantification. As metrology progresses, new

systems are available to measure across long

distances with very small losses in accuracy.

The older systems, such as theodolites, which

are accurate enough for use in the

construction industry, are gradually being

replaced by a new generation of optical

measurement devices using laser technology,

such as laser trackers and 3D co-ordinates

mapping systems (Metric Vision, 1995).

The authors

M. Saadat is a Lecturer and C. Cretin is a Researcher,

both at the School of Engineering, Manufacturing and

Mechanical Engineering, The University of Birmingham,

Birmingham, UK.

Keywords

Components manufacture, Measurement, Aircraft,

Assembly, Lasers

Abstract

The introduction of automation for the assembly of aircraft

wing box structures will require individual components to

conform closely to the CAD design specification with regard

to shape geometry and dimensional tolerances. Often, due

to a variety of previous manufacturing processes, the 3D

shape of these large components lose the accuracy of their

designed dimensional specifications. Under these

circumstances part-to-part assembly becomes tedious and it

would be impossible to rely on robots to achieve precise

assembly in an automated system. For this reason, variations

need to be accurately quantified in order to provide a

reliable prediction model in aid of any future automated

assembly. This paper describes the measurement method

used to record the possible variations occurring during the

assembly process. The measurements were made using a

laser tracker where the results are expected to offer some

explanations as to the causes of the variation. The suitability

of a laser tracker in a large assembly jig environment is then

assessed. This study is based on the work that was carried

out at BAE Systems UK, where the Airbus commercial

aircraft wings are manufactured.

Electronic access




available at


Research article

The authors wish to thank Airbus UK Ltd for its

sponsorship of this project, and its permission and

co-operation to allow measurement work to take

place during the production shifts at Airbus

Broughton plant, UK. The individual support

offered by Messrs Brian Turner, Raj Mistry, and

Paul Brandrick of Airbus UK is particularly

appreciated and acknowledged.

270

Assembly Automation

Volume 22 . Number 3 . 2002 . pp. 270–276


DOI 10.1108/01445150210436482

Measurement systems

A wing box consists of four major

components: the front spar, the rear spar, the

ribs, and the skins. The spars form the main

front and rear structures of the wing, called

the leading and trailing edge respectively. The

two spars are linked together by the ribs and

the ensemble forms the wing structure. The

skins, one on the top, the other at the bottom,

close the wing and cover the main surface of

the wing box. In assembly, the wing is held

vertically with the leading edge at the top in a

large jig structure. The jigs are designed for

easy access to all areas of the wing assembly,

and provide a strong, inflexible support for

the assembly process. The wing box

measurements described in this paper are

specific to the single aisle family of aircraft.

The jig has two levels in the first inboard half

of the wing in order to better cover its width,

and only one level in the outboard end as the

wing narrows down. The bottom floor of the

jig is inclined in order to follow the shape of

the wing since the leading edge is held

horizontally. Parts of the upper floor, closest

to the wing, can be folded back so that access

to the entire wing is possible. The structure is

schematically shown in Figure 1 (see also

Plates 1 and 2).

The measurement system must meet

certain criteria related to the size of the

component to be measured, and the required

accuracy. The accuracy of the measurement

process should be smaller than 30 per cent of

the tolerance band, as per Airbus quality

control guidelines (BAE Systems, 1998). This

represents approximately 1/30,000 of the size

of the wing. The goal of the measurement is

to compare positional data at different times,

and thus a reference system is necessary. The

system must also be able to be installed in the

same conditions at each step of the process.

The measurement process must take as little

time as possible, in order to cause as little

disruption as possible to a critical

manufacturing process. Finally, although the

jig is considered inflexible, there is a certain

amount of vibration occurring on the floor of

the jig. It is therefore necessary for the

measurement system to be separated from the

jig structure or the floor, so that any potential

movements would not affect the results of the

measurements (Fraser et al., 1999). Three

measurement systems have been considered

for this task:

(1) electronic coordinate determination

system (ECDS);

(2) photogrammetry; and

(3) laser trackers.

ECDS possesses the required range and

meets the accuracy requirements to complete

the measurements of the wing assembly.

However, the assembly jigs do not offer an

easy way to set up the ECDS stations outside

Figure 1 Wing assembly jig configuration

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Volume 22 . Number 3 . 2002 . 270–276

of the jig environment, which makes it less

reliable if vibrations occur onto the jig floor. It

is also a slow system to set up and collect data,

which could disturb the assembly process for

a longer time than necessary.

Photogrammetry offers a very good

solution, as far as speed and accuracy are

concerned (Beyer, 1995; Clarke and Wang,

1999). It can achieve the 1/30,000 accuracy

requirement and a large amount of data can

be collected in very little time. This system

only takes a few seconds to take a picture.

Photogrammetry also offers the advantage of

being unlinked to the environment.

Therefore, any vibrations or movements

occurring on the jig floor do not affect the

results of the pictures. The size of the wing is

outside the range of the available camera, but

it is possible to ‘‘cut’’ the wing in several parts

small enough to fit inside the range of the

camera. However, the camera requires the

targets to be present on every point measured

for each shot, which proved a costly solution.

Laser trackers are the most accurate

method to measure large components. The

wing box fits easily within the range of the

trackers. The assembly jigs have been built

and set up using trackers, and hence offer the

possibility to position a laser tracker inside the

jig, but independent of its floor or structure,

so that any potential vibrations are not

transmitted to the tracker. The laser tracker

can record points one by one, making only

one target holder necessary, which makes the

set-up much cheaper than photogrammetry.

The time required to collect the data online is

greater than offline systems such as

photogrammetry, though the required time is

less than using ECDS. For these reasons a

laser tracking system was selected as the

method of measurement for this study.

Measurement methodology

In order to carry out a comparative analysis of

the results it is necessary to follow a

methodology that includes:. a common set of features, which can be

measured throughout the process;. a stable reference system that can be used

to integrate the various sets of data.

The wing box is built in five stages as follows:

(1) Complete structure assembly (ribs,

leading edge and trailing edge).

(2) Drilling of the top skin.

(3) Drilling of the bottom skin.

(4) Bolting of the bottom skin.

(5) Bolting of the top skin.

The parts are bolted in the same position as

when they were drilled since the holes

determine the location of the parts.

Therefore, only the first three stages are of

interest to this study. A common feature to

these three stages of assembly is the location

of the holes in the rib through which a bolt

will attach the panel. This point is always

available and visible from the outside of the

wing box, making it a perfect reference point

for a half-inch corner cube. However, the jig

does not permit the installation of the laser

tracker on the bottom side of the wing: there

are no independent supports for the laser

tracker on that side, and the jig structure does

not allow for a continuous line of sight

throughout the length of the wing. The latter

actually restricts any type of continuous

measurement along the wingspan

independently of the method selected. The

Plate 2 Wing section in the assembly jig (by permission

of Airbus UK Ltd)

Plate 1 Wing section removed from the jig

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measurement of the variation from the upper

side of the wing was accepted to be sufficient

for the purpose of this exercise.

Since the measurements take place from the

outside of the wing, and a skin panel is to be

mounted onto the structure, the most external

measurement position would change when a

top skin is installed. It is therefore necessary

to measure the point defined by the

intersection of the centre line of the hole and

the inside face of the rib, shown in Figure 2.

Since this point is not visible from the laser

tracker, the method of ‘‘hidden points’’ is

used, together with a dual vector target

holder, to record the position of this point.

The target consists of two corner cubes as

shown in Figure 2. The laser tracker software

is set up to record the position of both targets.

From the dimensions of the dual vector

target, the system automatically calculates the

position of the ‘‘hidden point’’. A total of 27

points were selected on the wing as positions

to be measured, to give a general picture of

the deformation that may occur during the

installation of either skin panel.

In order to compare the results of each

measurement, it is necessary to measure in

identical co-ordinate system. The laser

tracker software offers great flexibility in this

area, and the co-ordinate system can be

recalculated each time as long as at least three

points are provided. A set of fixed known

points is necessary. The position of these

points is recorded at the beginning of each

measurement session using the default co-

ordinate system, usually based on the laser

tracker itself. The co-ordinates of these

points, in a particular reference system, are

imported from a database. By using ‘‘least

square best fit transformation’’ or ‘‘axis

alignment when using a minimum 3-2-1

control configuration’’ (Leica Geosystems,

1999), the points are transposed into the

co-ordinate of the database so that the laser

tracker can use this co-ordinate system. Since

these points are fiducial, the points measured

on the wing are not suitable. A set of five

targets was bolted onto the jig itself in order to

provide a fixed set of features. The position of

these targets was also measured in the jig

reference system, using least square best-fit

transformation method. This could eventually

be used to bring the measurements into the

wing co-ordinate system, so that the results

could be compared to the CAD design of the

wing.

Measurement procedure

The laser tracker was positioned on a

platform independent of the assembly jig. The

tracker was then left to warm up for one hour,

to ensure that the laser reached an optimal

temperature. The five reference points were

recorded using a 1½in. corner cube. An

associated software then re-calculated the

co-ordinate system so that the measurements

could take place in the jig reference co-

ordinate system. This would simplify the

comparison of the results.

The customised double vector target was

then installed into the first hole, and the

tracker recorded the position of the two ½in.

targets. The values were stored for later use.

The target was then moved onto the next

hole, and the procedure was repeated until all

the selected points were measured. The whole

process took over four hours, although the

disruption to the assembly cycle was less than

two hours.

The actual required position of the points

had to be calculated separately, but this task

was carried out offline. The two points

recorded on the assembly were used to

generate the third point, which is placed at the

centre of the hole, on the inside face of the rib

foot, as shown in Figure 2. This uses the two

recorded points to generate the equation of a

line passing through the centre of the hole.

The associated software uses the distance

from the first measured points to the

reference, to calculate the co-ordinate of the

reference point. These co-ordinates would

then be used to calculate the deviation

between each step of the assembly process.

When the assembly of the top skin had been

completed and all holes were drilled, the laser

tracker was brought back into the jig to

measure the new position of the rib feet as

Figure 2 Customised target holder

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Volume 22 . Number 3 . 2002 . 270–276

diagrammatically shown in steps given

Figure 3. The five reference points referred to

earlier were measured again, so that the

software could recalculate the co-ordinate

system used in the first set of measurements.

The previous set of data was loaded to the

software program so that the points to be

measured were known to the system. This

method is known as ‘‘build and inspect

mode’’ and ensures that the correct point is

measured. The tracker can find the point to

measure within a certain range, even though a

slight discrepancy may have occurred due to

the installation of the top skin. This helps

speed up the measurement process.

The custom target was then set into the first

position, and the laser tracker was able to

automatically find and record the positions of

the corner cubes. The operation was repeated

on each of the holes measured on the first set.

Figure 3 Relative positions and variations of measurement points during different stages of wing assembly

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Volume 22 . Number 3 . 2002 . 270–276

The tracker was then taken offline, to

calculate the position of the third point,

i.e. the reference position at the centre of the

hole on the inside face of the rib foot.

Although the measurement of these points

was much quicker than during the first set,

the positioning of the double vector target was

more difficult since the skin was in the way

when attaching it at the back of the rib foot.

The whole process took the same amount of

time as in the first set.

In the assembly jig, the top skin was

removed for deburring in order to offer an

easier access to the structure. The bottom

skin was then installed onto the structure.

After the holes were drilled and the panels

were slaved to the structure, the laser tracker

was brought back into the jig and was set up

to measure in the same co-ordinate system as

before. This is described in the steps shown

on the right hand side of Figure 3. The same

search feature was used as for the top skin,

which greatly improved the required time to

record the position of the two targets for each

hole. Since the top skin had been temporarily

removed, the measurement process was much

faster this time, and the disruption time was

reduced to one-and-a-half hours. The

software then calculates the third ‘‘hidden

point’’ offline.

Results and analysis

The results represent a set of co-ordinates

for a limited number of points of the wing

box assembly at different stages of the final

assembly. Each set of measurements uses

the same co-ordinate system, which was

created from the five fiducial points

described previously. For comparison

purposes, the first set of points, describing

the position of the ribs in the structure

without panels, were used as the reference.

The data from the two other sets were

imported separately from the first set of

data. The co-ordinate system is adjusted

using uniform weighting for each of the five

fixed points used as reference (Meid, 1999).

This method proves to be the most accurate.

It is, however, necessary to consider the

amount of error which is introduced by the

various changes of reference system by least

square best fit transformation (Calkins and

Salerno, 2000).

The software calculates the distance

between the points from the first set to the

points of the second set. These distances

represent the variation occurring between two

sets of measurements, i.e. the variation after

the top or the bottom panels are installed onto

the structure. Figure 3 shows graphs of the

average variation in terms of distance during

assembly corresponding to the measured

points given in the diagrams on their right

hand side. In this figure, variations of distance

are given for rear, centre, and front of the

wing. Variations occur at different directions

in space.

The installation of the top skin onto the

structure leads to some variations in the root

end area (i.e. area close to the fuselage)

especially toward the leading edge in the axis

parallel to the direction of flight. However,

the results suggest that the wing’s central area

is more prone to deformation than its edges in

the direction perpendicular to the line of

flight. There is also a noticeable variation in

the direction perpendicular to the skin, which

suggests that the rib is either pulled or pushed

by the panel, depending on the position along

the wing.

The installation of the bottom skin has a

certain effect on the opposite side of the ribs.

In both perpendicular and parallel directions

to the direction of flight, the variation is small,

though noticeably more significant near the

inboard end than toward the outboard end of

the wing. The data suggest that the bottom

skin tends to bend the ribs slightly toward the

inboard end. The bottom skin, similar to the

top skin, has a greater effect on the direction

perpendicular to the panels than any other

direction, which suggest that the installation

of the panels alters the profile described by

the outer edge of the ribs.

Although the laser trackers are extremely

accurate in laboratory environments, their use

on a shop floor can be subjected to larger

errors than expected (Calkins and Salerno,

2000). The discrepancies between the various

measurements, which have caused large

standard errors in some of the results, are due

to errors generated by the measurement

process. Although the laser tracker is a very

accurate measurement system, considering

the range of the equipment, its own

calibration is critical to the accuracy of the

results. The target holders could also be held

partly responsible. The holes that were used

to hold the customised target holder are

mostly pilot holes, and therefore their

accuracy in terms of diameter and direction is

questionable. It was necessary to use these

points for the measurement process since it

was the only feature available to measure the

overall profile of the wing during the various

stages of assembly. The dual target vector and

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Volume 22 . Number 3 . 2002 . 270–276

‘‘hidden point’’ method was necessary due to

the installation of the top skin, which hides

the hole from the tracker’s view. Although it

could have been possible to offset the skin

thickness, the variable thickness of the panel

along the wingspan would have made this a

very tedious operation and would not have led

to more accurate results than the ‘‘hidden

point’’ method.

The measurements were carried out on

three different assembly jigs. Although the

tolerance band for the assembly of the jigs is

relatively small, it is possible that the

differences between each of the three jigs

caused a slight difference in the way the rib

deforms under the installation of the skin

panels. Another factor influencing variation

is the environmental condition in which the

measurements were carried out. The

temperature differences during

measurement periods for each set is less

than 48C. This should not greatly affect the

variation considering that the wing

components are made of an aluminium-

based alloy with a coefficient of expansion of

24mm/m/K. Over the entire 20m length of

the wing these values would lead to an

expansion of less than 2mm, which is

insufficient to explain the lack of

repeatability in the position of the rib foot,

and its variation between each built.

It was possible to measure various other

components such as the rib profile during the

measurements of the structure. Several rib

surfaces were scanned in order to assess the

initial alignment of the rib between the front

and rear spar in the assembly jig. The results

of these measurements show that the rib does

not stand perfectly aligned between the two

spars caused by the misalignment of the two

flanges onto which the rib is attached.

Similarly, from the data provided by the

supplier responsible for the forming of the

skin panel, it appears that the curvature of the

panel is subject to large variations. These are

explained by the difficulties encountered in

the shot peening of large components as well

as the relatively large tolerance band allocated

to this process.

Conclusions

Use of a laser tracker is the preferred solution

for the in-production measurement of large

components due to its advantages, including

accuracy, target design costs, and the

provision of a customised holder. The

accuracy requirements for this study allowed

the use of the absolute distance meter (ADM)

when recording the second and third sets of

points for each wing in order to save time.

The ADM method may not always be

suitable, since the accuracy of the results is

affected. There are several methods available

to calculate the uncertainty introduced by the

various methods of measurement available

when using a laser tracker. However, if such a

measurement was to take place on a regular

basis, the laser tracker may not be so

appealing a solution. Laser trackers are far

more expensive than photogrammetry,

although the number of required targets by

photogrammetry is much greater. This would

increase the costs involved in the manufacture

of the targets.

References

BAE Systems (1998), ‘‘Airbus UK metrology guidelines’’,Measurement Handbook, Airbus UK internaldocument, BAe Samlesbury, Refs MA&A-QA-MH-0001 and DIN 2257.

Beyer, H. A. (1995), ‘‘Digital photogrammetry in industrialapplications’’, IAPRS, Vol. 30, Part 5W1, ISPRSIntercommission Workshop: From Pixels toSequences, 22-24 March, Zurich.

Calkins, J.M. and Salerno, R.J. (2000), ‘‘A practical methodfor evaluating measurement system uncertainty’’,Boeing Large Scale Metrology Conference, CA.

Clarke, T. and Wang, X. (1999), ‘‘An embedded metrologysystem for aerospace applications’’, CMSC ’99,26-30 July, Seattle.

Fraser, C.S., Morrison, R. and Kinzel, R. (1999),‘‘Deformation measurement of the world’s largestelectric ring motor’’, CMSC ’99, Seattle, 26-30 July.

Leica Geosystems (1999), Axyz Training Manual forTracker, Ref. 712390, Version 1.3.0, AG,Switzerland. .

Ligget, J.V. (1993), Dimensional Variation ManagementHandbook – A Guide for Quality, Design andManufacturing Engineers, Prentice-Hall, EnglewoodCliffs, NJ.

Meid, A. (1999), ‘‘Individual vs uniform weighting ofmeasurements and constraints in industrialmeasurement networks’’, Leica Geosystems, CMSC’98, Saint Louis, 6-10 July.

Metric Vision (1995), Non-contact Large-envelopePrecision Measurement: CLR 100 3D Co-ordinateMapping System, Metric Vision document, Gateway95, Newington, VA.

276



Assembly Automation

Volume 22 . Number 3 . 2002 . 270–276

FAS scheduling basedon operation flexibility

Rong-Lei Sun

Youlun Xiong

Runsheng Du and

Han Ding

1. Introduction

Digitization is considered as one of the most

important features of future manufacturing.

Interconnected networks have made it

possible for a product to be manufactured at

one place, which may be far away from where

the product is designed. Moreover, the

equipment used to produce a product in one

factory may be different from what is used to

produce the same product in another factory.

This implies that the process plan of a

product may differ from one factory to

another. In order to adapt to the changes of

the manufacturing environment it is not

sufficient any more for process planners to

provide only the optimal process plan that is

suitable to a particular manufacturing system.

Actually, they should provide for

manufacturers all possible process plans and

leave the selection of an executable process

plan to the manufacturing procedure. By so

doing, maximum processing flexibility

provided by a product is maintained. During

the manufacturing procedure, a scheduler can

select from the candidate plans the one that is

most suitable to a particular manufacturing

system. In some cases the selection is even

performed dynamically, according to the state

of the manufacturing system.

Even for a particular manufacturing system,

there are benefits from multiple process plans

in terms of reducing completion time,

decreasing load unbalance of the working

equipment, and quickly responding to

unpredictable events. Some investigations

demonstrate that the performance of flexible

manufacturing systems is improved

significantly if multiple process plans are

provided (Gindy and Ratchev, 1998; Gindy

et al., 1999; Kim et al., 1997; Kim and

Egbelu, 1999; Sun et al., 2001).

Under the framework of the new generation

of manufacturing systems, such as agile

manufacturing, holonic manufacturing and

multi-agent manufacturing, etc., the

machining equipment is more or less

intelligent, autonomous and co-operative

(Kim et al., 1997; Kim and Egbelu, 1999;

The authors

Rong-Lei Sun is a PhD student and Youlun Xiong,

Runsheng Du and Han Ding are Professors in the

School of Mechanical Science and Engineering, Huazhong

University of Science and Technology, Wuhan, People’s

Republic of China.

Keywords

Flexible assembly, Scheduling, Operations planning,

Evaluation

Abstract

Multiple assembly sequences can increase the flexibility of

assembly systems and consequently lead to better

performance. The relationship between multiple assembly

sequences and their impact on the performance of

assembly systems are studied. Based on the concept of

operation flexibility, this paper presents a flexibility

measure to evaluate each operation sequence. A

flexibility-based criterion is proposed to prioritize each

operation, which is then used to guide the assembly

scheduling. A simulation study demonstrates that when

using the criterion, higher system flexibility is achieved

and consequently better performance of the assembly

systems is obtained.

Electronic access




available at


Research article

The research work was supported by the National

Nature Science Foundation of China (Grant

No. 59990470, 59985004) and by the National

863 Hi-Tech Plan of China (Grant No.

2001AA412140). It was also supported by the Key

Lab of Intelligent Manufacturing Technology of

National Education Ministry.

277

Assembly Automation

Volume 22 . Number 3 . 2002 . pp. 277–282


DOI 10.1108/01445150210436491

Sun et al., 2001). Such a manufacturing

paradigm not only provides a mechanism to

make full use of alternative process plans, but

also requires multiple process plans to

support its negotiation or bid mechanism. It is

clear that the multiple process plans are also

requested by the new generation of

manufacturing systems.

Some researchers recognize that process

alternatives are crucial to improve the

performance of manufacturing systems, and

take into account multiple process plans in

their studies (Gindy and Ratchev, 1998;

Gindy et al., 1999; Kim et al., 1997; Kim and

Egbelu, 1999; Sun et al., 2001). A typical

method is to select from all feasible plans the

optimal one suitable to a particular

manufacturing system. When the system is

changed (such as changes of orders, machine

breakdown, etc.), it needs to re-select another

optimal process plan. One major drawback of

the scheme is lack of adaptability to

unpredicted events. Also the optimal solution

must be recalculated for every different

manufacturing system.

Another method commonly adopted to deal

with multiple plans is to take all possible

process plans into consideration throughout

the manufacturing process (Kim et al., 1997;

Kim and Egbelu, 1999). That is, the shop

managers do not select an optimal plan in

advance. The process plan which is selected is

dynamically determined according to the

real-time state of the manufacturing system.

During the decision-making procedure, all

candidate plans are treated equally. They are

assigned equal priority to be selected.

However, from the viewpoint of operation

flexibility (Tsourveloudis and Phillis, 1998),

when a manufacturing procedure is used with

a different process plan it will lead to a

different operation flexibility. Some lead to

higher flexibility while others lead to lower.

Thus the manufacturing process should use

the plan with the highest flexibility. Sun et al.

(2001) go one step further with this research

direction. They prioritized multiple operation

sequences using a decision space method. But

in a multi-phase decision-making procedure,

what we need to determine is which operation

will be performed at the next step, rather than

select a whole operation sequence.

This paper focuses on prioritizing assembly

operations when multiple assembly sequences

are available in flexible assembly systems

(FASs). We study the relationship between

multiple operation sequences and provide a

flexibility measure for operation sequences. A

criterion is proposed to prioritize operations

(rather than sequences), which can be used to

guide the decision-making procedure during

production scheduling such that there is

adequate flexibility at each decision point.

Experimental results demonstrate the

efficiency of the criterion when it is used as a

scheduling heuristic for FASs. It may improve

flexibility of assembly systems, and

furthermore, improve the performance of

systems. The rest of the paper is organized as

follows. First, in the next section, we outline a

framework integrating scheduling and process

planning. In section 3, we represent multiple

operation sequences as a tree and study

flexibility of operation sequences. A criterion

used to prioritize operations is proposed in

section 4. Simulation experiments and

experimental results are introduced in

section 5. Finally, in the last section, we

conclude the whole paper.

2. Framework integrating schedulingand process planning

Use of alternative process plans under the

FAS environment needs integration of

relevant techniques. Figure 1 depicts such a

proposed framework. Functions of major

components are briefly introduced in the

following sub-sections.

The assembly planner receives product data

from the CAD model and outputs:. Assembly sequence plans, which are then

sent to the scheduler.. Assembly operation plans, which are then

sent to machine controllers (MCs), where

the operation plans are analyzed and

transformed to instructions controlling

the assembly stations to perform the

assembly operations.

The scheduler receives the assembly sequence

plans and real-time states of the assembly line

from the assembly planner and the FAS

respectively. Then it outputs instructions

scheduling the FAS.

A prototyping system of the assembly

planner is being developed and some initial

results have been obtained (Niu et al., 2001;

Xiong et al., 1998, 1999). This paper,

however, focuses on FAS scheduling.

278

FAS scheduling based on operation flexibility

Rong-Lei Sun, Youlun Xiong, Runsheng Du and Han Ding

Assembly Automation

Volume 22 . Number 3 . 2002 . 277–282

3. Representation and flexibilityevaluation of multiple assemblysequences

Multiple assembly sequences are usually

formulated as a tree (Figure 2), which is

called a plan tree of assembly sequences (or

plan tree for short). A node in the tree

represents an assembly operation. An edge

represents the precedence relationship

between the two assembly operations

connected by the edge. A path starting with

the root and ending at a leaf represents an

assembly sequence plan. A sub-path starting

with a node other than the root and ending at

a leaf represents an assembly sequence sub-

plan. For dynamic scheduling in FASs the

assembly procedure for a product is

transformed to a multi-phase decision-making

procedure when assembly sequences are

formulated as a tree. Each time a node is

processed the scheduling system needs to

determine which sub-node of the node will be

processed next. In most research articles each

sub-node is assigned with the same priority

and has the same opportunity to be selected at

decision points. This method is not

recommended since the flexibility of the

manufacturing systems is affected

significantly by the operation sequence

selected. For example, in Figure 2, after node

3 has been processed, if both nodes 7 and 8

can be processed next, we would rather select

node 8 than node 7 by intuition.

Definition 1

Operation flexibility of a product refers to the

ease of changing the sequence of operations

Figure 1 Framework integrating scheduling and process planning

Figure 2 A plan tree of assembly sequences

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Assembly Automation

Volume 22 . Number 3 . 2002 . 277–282

that are required to manufacture the product

(Tsourveloudis and Phillis, 1998).

It is worth noticing that the operation

flexibility depicts possible assembly sequences

derived from the product CAD model. It is

the outcome of assembly sequence planning

and is sent to the scheduler in the proposed

framework in Figure 1. Operation flexibility is

quantified using the number of different

assembly sequences by which the product

may be assembled. When the assembly

sequences are formulated as a tree, the

operational flexibility of a product is equal to

the number of paths (or leaves) existing in the

tree.

Definition 2

In a plan tree of assembly sequences, the

number of leaves covered by a sub-tree

starting with node i is called the flexibility of

the node i.

According to the definition we have that

the operation flexibility of a product

decreases monotonously when the product

is being assembled. For example, in Figure

2, consider assembly sequence S1. The

product has maximal operation flexibility at

the beginning. It has in total nine possible

assembly sequences. When node 1 has been

processed, its operational flexibility drops to

four, which means there are four possible

assembly sequences remaining after nodes 0

and 1 have been processed. Further, after

the leaf 1 is processed, the assembly

procedure of the product has been finished

and there is no possible assembly sequence

to be selected.

Node flexibility represents the remaining

operation flexibility of a product when some

operations are finished. In a plan tree of

assembly sequences, node flexibility is labeled

in the circle representing the node.

Since multiple assembly sequences can

efficiently improve the performance of FASs,

the operation flexibility should be maintained

as much as possible. For a rule-based

dynamic scheduler, however, scheduling is

fulfilled through a multi-phase decision-

making procedure. That is, when a node has

been processed, the scheduling system must

determine which sub-node will be processed

next. Thus, what we are really interested in is

whether or not there are an adequate amount

of sub-nodes at each decision point.

Therefore, the assembly procedure for a

product should follow an assembly sequence

that satisfies the following:. It has totally reasonable flexibility.. The flexibility is distributed uniformly

among the nodes locating in the

sequence.

For such an assembly sequence, each node

has an adequate amount of candidate

operations from which a node can be selected

as the next operation. When the assembly

procedure is performed along with the

sequence, it will increase the flexibility of

FASs.

4. Evaluation of node priority

Definition 3

Let OP0, OP1, . . . , OPn be a path of a plan

tree of assembly sequences. Let F0, F1, . . . , Fn

be the node flexibility of node OP0, OP1, . . . ,

OPn respectively.

r ¼ 1

n

Xni¼1

Fi

Fi�1

is called flexibility reduction rate of the path (or

flexibility reduction rate of the assembly

sequence).

Node priority

In a plan tree of assembly sequences, the

priority of node i is denoted by wi, which is

the average flexibility reduction rate of the

paths including node i. During the decision-

making procedure a node is with higher

priority if it has lower w.

For example, in Figure 2, the flexibility

reduction rate of path S1, S5, S7 and S8 can

be calculated as follows:

r1 ¼ 1

4

4

9þ 2

4þ 1

2þ 0

1

� �;¼ 0:361

r5 ¼ 1

4

2

9þ 2

2þ 1

2þ 0

1

� �¼ 0:431

r1 ¼ 1

4

3

9þ 1

3þ 1

1þ 0

1

� �¼ 0:417;

r8 ¼ 1

4

3

9þ 2

3þ 1

2þ 0

1

� �¼ 0:375

The priority of node 1, 2 and 3 is:

w1 = (r1 + r2 + r3 + r4)/4 = 0.361;

w2 = (r5 + r6)/2 = 0.431;

w3 = (r7 + r8 + r9)/3 = 0.403.

Thus, the node 1 has the highest priority

while the node 2 has the lowest priority.

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Assembly Automation

Volume 22 . Number 3 . 2002 . 277–282

By defining the node priority, the

scheduling system can select a node with the

highest priority at each decision point so as to

increase the flexibility of assembly systems,

and furthermore, improve the performance of

assembly systems.

5. Simulation study

Consider an FAS consisting of three assembly

stations and three kinds of products. Product

1 includes four assembly operations: OP1,

OP2, OP3, OP4; product 2 includes four

assembly operations: OP2, OP4, OP5, OP6;

product 3 includes four assembly operations:

OP3, OP4, OP5, OP6. Each product has

multiple operation sequences that are

depicted in Figure 3. Each assembly station

can perform at least one operation. Assembly

time needed by an assembly station to

perform an operation is shown in Table I.

The assembly procedure is scheduled using

rule-based dynamically scheduling system.

Combination priority rule is as follows.

(1) Select an operation with highest priority

(i.e. lowest w).

(2) Select an operation with lowest

competition degree[1].

(3) The assembly station with the most

processing efficiency wins the

competition when several stations

compete for the same operation.

For comparison, we conduct experiments

under two conditions: considering operation

flexibility (experiment 1) and not considering

operation flexibility (experiment 2). The

experimental results are depicted in Figures 4

and 5 respectively. Performances obtained

from the experiments are summarized in

Table II. From the experimental results we

can conclude that the performances of the

assembly system are improved significantly

when considering operation flexibility.

6. Conclusions

Multiple assembly sequences can increase

the flexibility of assembly systems and

Figure 3 Plan trees of assembly sequences for products 1, 2 and 3

Table I Assembly time of operations performed on

stations

Station 1 Station 2 Station 3

OP1 50 60 –

OP2 120 – 100

OP3 110 130 120

OP4 60 70 –

OP5 – 100 70

OP6 – 100 110

Figure 4 Gantt chart of experiment 1

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Assembly Automation

Volume 22 . Number 3 . 2002 . 277–282

consequently lead to better performance.

We studied the relationship between

multiple assembly sequences and their

impact on the performance of assembly

systems. Based on the concept of operation

flexibility, we present a flexibility measure to

evaluate each assembly sequence. A

flexibility-based criterion is proposed to

prioritize each operation, which is then used

to guide the decision-making procedure

during assembly scheduling. Simulation

study demonstrates that when using the

criterion we may increase system flexibility

and consequently improve the performance

of assembly systems. Scheduling based on

operational flexibility is a sophisticated

problem. In this paper, only the precedence

constraint is considered in the plan tree. To

make this method more practical, it should

take into account the complexity of each

operation and the time needed to perform an

operation.

Note

1 Competition degree of operation: the number of idlestations that can process the operation at currentinstant.

References

Gindy, N.N.Z. and Ratchev, S.M. (1998), ‘‘Integratedframework for selection of machining equipment inCIM’’, Int. J. Computer Integrated Manufacturing,Vol. 11 No. 4, pp. 311-25.

Gindy, N.N., Saad, S.M. and Yue, Y. (1999), ‘‘Manufacturingresponsiveness through integrated process planningand scheduling’’, Int. J. Production Research, Vol. 37No. 11, pp. 2399-418.

Kim, K.H. and Egbelu, P.J. (1999), ‘‘Scheduling in aproduction environment with multiple process plansper job’’, Int. J. Production Research, Vol. 37 No. 12,pp. 2725-53.

Kim, K.H., Song, J.Y. and Wang, K.H. (1997), ‘‘Anegotiation based scheduling for items with flexibleprocess plans’’, Computers Ind. Engng, Vol. 33,No. 3/4, pp. 785-8.

Niu, X., Ding, H. and Xiong, Y. (2001), ‘‘A virtualprototyping approach to assembly sequenceplanning’’, Proceedings of 2001 InternationalConference on eCommerce Engineering: NewChallenges for Global Manufacturing in the 21stCentury, 16-18 September, Xi’an.

Sun, R.L., Ding, H. and Xiong, Y.L. (2001), ‘‘Decision spaceapproach to operation selection consideringalternative assembly sequences’’, Proceedings of 2001International Conference on eCommerce Engineering:New Challenges for Global Manufacturing in the 21stCentury, 16-18 September, Xi’an.

Tsourveloudis, N.C. and Phillis, Y.A. (1998),‘‘Manufacturing flexibility measurement: a fuzzylogic framework’’, IEEE Trans. on Robotics andAutomation, Vol. 14 No. 4, pp. 513-24.

Xiong, C.H. and Xiong, Y. (1998), ‘‘Stability index andcontact configuration planning for multifingeredgrasp’’, J. of Robotic Systems, Vol. 15 No. 4,pp.183-90.

Xiong, C.H., Li, Y.F. and Xiong, Y. et al. (1999), ‘‘Graspcapability analysis of multifingered robot hands’’,Robotics and Autonomous Systems, Vol. 27 No. 4,pp. 211-22.

Table II Performance comparison considering and not considering operation

flexibility

Average Average Load

Completion time assembly utilization unbalance

Average Maximal time (%) (%)

Experiment 1 346.7 360 346.7 96.3 2.56

Experiment 2 360.0 390 343.3 88.0 14.24

Figure 5 Gantt chart of experiment 2

282



Assembly Automation

Volume 22 . Number 3 . 2002 . 277–282

Mini features

Delphi uses Negari system to supportlean manufacturing and provideproduction flexibility

Keywords Automation, Assembly, Automotive

Modular Automation, from Birmingham, has

designed and built a new semi-automatic

assembly system for Delphi Diesel, of

Sudbury, that complies with the company’s

lean manufacturing principles (see Plate 1).

The system is the fourth line supplied by

Modular Automation for the same

application. The three previous lines were

supplied while the company was Lucas Diesel

Systems.

The system assembles diesel injector units

to the correct tolerance by using precision

shims to compensate for machining

limitations and the inevitable variations in the

tension of the springs used in the injector

body. By choosing a shim of exactly the

correct thickness, Delphi can vary the

opening pressure of the valve to achieve a

complete injector assembly that operates

correctly first time. The injectors are

subsequently wet tested to verify that

accuracy.

The additional line is a direct response to an

increasing demand for Delphi’s products. At

each stage, Modular Automation has

respected Delphi’s principle of balancing the

relative benefits of automation against manual

assembly. There is no doubt that it is

technically possible for all operations to be

performed automatically, however, Delphi’s

lean manufacturing principles require that

automation is only introduced where there is

a clear quality and economic case to do so.

The new system operates on a Negari

principle, which allows production volumes to

be varied depending on the number of

operators allocated to the line. A single

operator can operate all machines in

sequence; however, up to four operators can

work on the same line to create a

proportionate increase in production rates.

This system is intended to provide the

production flexibility needed to support the

three machines already in service and react

quickly to fluctuations in demand for the

product. When the product eventually is

withdrawn from service, the Negari line will

be able to provide service components

precisely to reflect demand with the minimum

of downtime.

Modular Automation has vast experience at

developing innovative assembly systems using

a modular approach and trusted technology.

By approaching its business in this practical

way it ensures that its systems are realistically

priced, effective and utterly reliable.

Enquiries to: William Bourn, Modular

Automation, Talbot Way, Small Heath

Business Park, Birmingham, B10 0HS, UK.

Tel: +44 (0)121 766 7979; Fax: +44 (0)121

766 6385; E-mail: [email protected]

PHASA assembly is key to productivity

Keywords Plastics, Rivets

A PHASA 20/40 series machine producing 90

off riveted fixings every cycle is the key to high

productivity on critical assemblies at the heart

of central locking control units for

Scandinavian vehicle manufacturer Saab (see

Plate 2).

The equipment, from Harlow-based

PHASA Developments, is used to secure

moulded key fob housings to PCB

motherboards, which are nested together to

allow 30 individual units to be processed in a

single cycle. In operation, the motherboards

are first mounted in a special-purpose

turnover fixture. Individual key fob housings

are then positioned onto the PCB from above,

using three moulded pegs for location. The

fixture subsequently clamps the components

in position, before inverting them ready for

the hot air staking process.

Plate 1 The new manufacturing system for Delphi Diesel of Sudbury,

designed and built by Modular Automation, complies with the company’s

lean manufacturing principles

283

Mini features Assembly Automation

Volume 22 . Number 3 . 2002 . 283–289

During the PHASA machine’s automatic

cycle, a custom-designed manifold

arrangement directs air at 3008C precisely

over the 1.5mm diameter pegs to bring them

to their plastic state. Cold forming tools then

reshape them into riveted heads, which cool

and solidify to produce a permanent,

vibration proof fastening.

According to PHASA’s John Neugebauer,

the development of the latest equipment for

Saab follows the success of a similar contract

for Rover. ‘‘We have proven the suitability of

plastic hot air staking for this type of work

over a number of years. Our track record

includes refining the process to produce more

than 200 fixings in a single operation. As a

result, customers throughout the

telecommunications, IT and domestic

appliance sectors can undertake PCB

assembly applications extremely

cost-effectively.

‘‘The system’s ability to assemble 30 off

units within a single 16 second cycle is a key

factor in achieving our customer’s required

production rates. What is more, this

capability is backed by inherent repeatability

and consistency, which enables Cpk figures in

excess of 2.0 to be achieved by most users –

the equivalent of less than one reject per

million operations.’’

‘‘Hot air staking not only offers a simple and

effective method of producing permanent,

low-cost fastenings, but is also suitable for the

pre-loading of seals, or the retention of

bearings and threaded inserts’’, he continues:

‘‘It has therefore become a first choice

assembly method for thermoplastic materials

across a wide range of automotive industry

applications – from lamp assemblies to

interior trim retention.’’

For more information contact:

International House, Horsecroft Road,

Harlow, Essex CM19 55U, UK. Tel: +44 (0)

1279 630200; Fax: +44 (0) 1279 630222. E-

mail: [email protected]; www: phasa.co.uk

Moving parts can be built pre-assembledby automated prototyping system


Stratasys has introduced the Prodigy Plus2,

an office-based prototyping system that

incorporates the automated support-removal

system called WaterWorks2. This system

uses a water-based solution to simply dissolve

the model’s temporary support structures,

which eliminates the need for manual

removal. Besides automating the process, it

lets users build models with complex

geometry, smaller features, and finer detail.

With WaterWorks, users can make models

with moving parts that are built

pre-assembled. It allows the creation of

intricate parts that are impossible to build

otherwise. The system is based on the

platform of the company’s successful Prodigy

system, introduced in 2000.

Besides the soluble support removal system,

Prodigy Plus is outfitted with Insight2

preprocessing software developed for

Stratasys’ higher-end systems. The

proprietary software offers users a high degree

of control over workflow and model building.

For efficiency, the software lets users build

multiple parts simultaneously. At the user’s

workstation, Insight reports system status,

job-build status, and a build log, which

includes material used, material required, and

material remaining. When a model is

complete, Insight notifies the user by e-mail

or pager.

‘‘For too long, the features of higher-end

RP systems have been out-of-reach for many

Plate 2 Plastic hot air staking technology from PHASA

Developments has been selected for the production of

critical PCB assemblies at the heart of central locking

control units for Scandinavian vehicle manufacturer Saab

284


Volume 22 . Number 3 . 2002 . 283–289

organizations’’, says product manager Mary

Stanley. ‘‘It is part of our mission here at

Stratasys to lower the cost of modeling and

prototyping to make it cost-effective for a

broader market. Offering hands-free support

removal in a lower price system is proof we

are on track.’’

Prodigy Plus is quiet, safe, and compact.

Like all Stratasys equipment, it requires no

special facilities or venting and involves no

hazardous materials or byproducts. It has a

build envelope of 8 6 8 612 in. (203 6 203

6 305mm) and measures 27 6 34 6 41in.

(686 6 864 6 1,041mm). The system has

three options for surface-finish resolution:

fine, standard, or draft. Its software operates

on the Windows NT or 2000 platforms.

Stratasys systems typically represent the

lowest total cost of ownership among the

major rapid prototyping suppliers.

For further information contact:Stratasys

Inc. Corporate, 14950 Martin Drive, Eden

Prairie, Minnesota, USA 55344-2020. Tel.

+1 9529373000; Fax: +1 9529370070; www:

stratasys.com

ElectRelease – electrically dis-bondingepoxy

Keywords Adhesives, Disassembly

A high strength adhesive that, despite its

tenacious bond, can be separated or

dis-bonded by the application of a low dc

voltage is now available commercially under

the name ‘‘ElectRelease’’.

ElectRelease is a two-part, room

temperature curing, epoxy with a lap shear

strength of 2,500psi that bonds to most

metals used in industrial or scientific

application including aluminium alloys,

stainless steel and copper (see Plate 3).

When subjected to a low dc voltage the

bond at the positive surface releases cleanly

and quickly.

The development of ElectRelease was

originally stimulated by the need to attach,

and subsequently remove without damage or

blemish, test equipment to the exterior of

supersonic aircraft.

Now in full-scale production, ElectRelease

is already in evaluation for a wide variety of

commercial and industrial applications

including automotive, aerospace, ship

building and environmental monitoring

systems.

Technical data, applications advice, and

further information are available from:

Electromotif Ltd.

Contact: Don Haydon, Electromotif Ltd.

Tel: +44 (0) 20 8296 0650; Fax: +44 (0)20

8296 0649; E-mail: [email protected]

Pedal power through laser transmissionwelding

Keywords Laser welding, Automotive

A high power, direct diode laser transmission

welding system, from Herfurth Laser

Technology, of Coventry, is being used by

Birkby’s Plastics Ltd in the manufacture of a

new, electronic throttle control (ETC) pedal

assembly for motor vehicles. The pedal,

which is manufactured as a glass-filled nylon

moulding, is being fitted initially to certain

Ford models but it has wide-ranging

application in the automotive industry (see

Plate 4).

Birkby’s Plastics, of Liversedge, has an

international reputation as a designer,

manufacturer and assembler of plastic

components for the automotive and business

electronics markets, using state-of-the-art

technology. Its new ETC pedal features an

integrated, rather than a bolt-on, sensor,

making it compact, economical and

tamperproof compared with competitive

systems. When it is operated by the vehicle

Plate 3 ElectRelease

285


Volume 22 . Number 3 . 2002 . 283–289

driver, a demand signal is transmitted to the

engine management system, which compares

it with the ignition map, allowing the engine

to be precisely fuelled to optimise efficiency,

in terms of economy, performance and

emissions.

The integration of the sensor within the

pedal housing relies on welding the

electronics ‘‘pot’’ precisely in position.

Because the pot needs to be exactly located

and zeroed, it was impractical to achieve the

weld between the two plastic components by

vibration welding. Furthermore, because

two different grades of glass-filled nylon,

with two different melting points, are used

for the pot and the pedal, it was also

impossible to weld the components together

using heating techniques and ultrasonic

welding.

The solution to the problem was found in

direct diode, laser transmission welding. This

technology relies on the fact that a joint can

be produced between two plastic components

if one component transmits high power laser

energy and the other absorbs it. In many

cases, the strength of such a joint can exceed

that of the parent materials. In addition,

unlike conventional laser welding techniques

for plastics, which employ fibre optics, high

power direct diode laser welding can generate

a beam width of up to 20mm. Furthermore,

the diode array ensures that sufficient, evenly

distributed, controlled energy can be

delivered across this beam width to achieve

the weld required.

After successful trials at Herfurth Laser

Technology’s development centre at the

University of Warwick, a direct diode laser

transmission welding system has been

supplied to AB Precision Ltd (ABP), one of

the UK’s leading automation specialists, for

incorporation into an automated assembly,

weld and test line, which they have purpose-

designed and built for Birkby’s. The welding

system carries out the welding of the two

glass-filled nylon components of the

electronic control throttle pedal assembly. It

produces a 3mm wide weld and also

hermetically seals the pot within the pedal. It

is robot-mounted to ensure replicability of the

welding operation and requires no bespoke

tooling.

Enquiries: Richard Icke, Herfurth Laser

Technology Ltd, Barclays Venture Centre,

University of Warwick Science Park, Sir

Williams Lyons Rd, Coventry CV4 7EZ, UK.

Tel: +44 (0) 2476 323088; Fax: +44 (0) 2476

323001.

Yellow goods laser

Keywords Lasers, Cutting

In 1951 the late Basil Thwaites unveiled his

first ‘‘dumper-truck’’. Fifty years on the

company which continues to bear his name is

still the world’s leading producer of such

vehicles – exporting them to more than 70

countries.

In the late 1990s, some time after most

manufacturers of off-road vehicles had

already embraced laser technology, two

factors emerged to alter this situation – one

general, and one specific. In general, more

powerful lasers were now available – these

enabled both the cutting of thicker materials,

and the cutting of medium gauges of material

much faster than before. Also in Thwaites’

particular case a new Unigraphics CAD

system had been installed, in preparation for

the design of a new product range. These new

products could be designed from the outset

with laser profiling in mind. The production

freedom offered by laser-processing would

allow Thwaites’ designers to realise more of

Plate 4 The electronic control pedal, which is

assembled with the aid of direct diode laser

transmission welding from Herfurth Laser Technology

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Volume 22 . Number 3 . 2002 . 283–289

the potential of their new CAD system than

any other cutting process would.

Further benefits factored into their

justification included an improved material

utilisation – needed to offset rising material

costs. The ‘‘flying-optic’’ approach to cutting

did not necessitate sheet clamping. It also

enabled the cut-widths and skeleton web-

thicknesses on sheet nests to be reduced

compared with their old Plasmapress and

oxy-propane cutting nests. Additionally, the

tool-free nature of the process enabled them

to place lower batch size orders onto the shop

– leading to inventory and other production-

control benefits. A further production

advantage over their existing facilities was

provided by an automatic pallet-exchange

system, combined with the ability to run a

laser machine unmanned into the night at the

end of a late shift (Plate 5).

The idea of using ‘‘tongues’’ and slots in

respective components to enable ‘‘jig-free’’

assembly is far from new. But at Thwaites

they have taken this idea to new heights or

should one say depths – by ‘‘cashing-in’’ on a

Trumpf laser’s ability to produce ‘‘narrow’’

slots in their thick plate components. In many

instances welding jigs have been eliminated,

but even the remaining jigs are now much

simplified, by using this tongue and slot

technique – particularly in the area of vehicle

sub-frame assembly. Jig elimination,

although most noticeable among the major

sub-assemblies, is by no means confined to

this area. According to John Tebaldi, it is also

significant in the detail production area. On

older machine models, any components

thicker than about 10mm were profiled on

their gas-cutting machine. This meant that

any holes needed in them had to be

subsequently drilled. Also, even on thinner

parts, if any ‘‘small’’ holes were required – i.e.

holes smaller in diameter than plate thickness,

then they also had to be drilled rather than

punched. However, on their new model, holes

and slots as small as 40 per cent of plate

thickness are now produced by laser, at the

same time as the larger profiles. Not only has

this eliminated ‘‘second-ops’’ – with all their

extra handlings, setups, and machining times

– but it has also eliminated literally dozens of

drilling jigs on this one new model alone.

Another envisaged benefit, which Thwaites

can now confirm, is a reduced manning

requirement when compared with their other

machines. One feature of the L3030 which

they do exploit is its ability to run unmanned

into the night, without any operator

involvement, and without any of the other

control and management resources usually

associated with running an FMS or

‘‘lights-out’’ facility. At the end of the late

shift the operator makes sure that the machine

is loaded with two fresh sheets of raw

material. One goes into the cubicle for

cutting, and one onto the second pallet ready

for use. On completion of the first sheet, the

pallets exchange and the second job is cut. On

completion of the second job, the machine

shuts itself down in a controlled and safe

manner – ready for unload next morning.

Obviously, when working in this lights-out

mode they only load proven work, but by

choosing long-cycle jobs – usually in their

slower-profiling, thicker materials of up to

20mm – they can often obtain two or three

hours per night of ‘‘free’’ production: in fact

up to six hours has been achieved.

For more information contact: Trumpf

Limited, President Way, Airport Executive

Park, Luton, Beds, LU2 9NL, UK. Tel: +44

(0) 1582 725335; Fax: +44 (0) 1582 399250.

AGCO schedules tractor assembly withTecnomatix eM-Power sequencer

Keywords JIT, Production management

As the complexity of tractors has increased in

recent years, so has the problem of scheduling

production. To avoid bottlenecks on the final

assembly line it is necessary to schedule the

release of production orders in a way that

allows for the impact on workload as each

machine moves through the production line.

This is achieved by sequencing the orders, a

Plate 5 Thwaites choose Trumpf’s L3030

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Volume 22 . Number 3 . 2002 . 283–289

computer process designed to match the

workload against available capacity and

logistics to achieve an optimum throughput

from the factory.

AGCO’s Massey Ferguson tractor factory,

in Coventry, produces about 60 tractors a

day, all of which are more or less unique

products. Every machine is built to order and

customers can choose from a wide range of

features and options covering engine size,

drive transmission, cab equipment and

functional accessories. There are two main

product platforms, the 200 Series is the utility

workhorse, renowned for easy maintenance,

and the more sophisticated 4300 Series,

which offers world class refinements in

comfort and performance (see Plate 6).

Currently a new order for a tractor takes

between six to eight weeks to deliver. The

SGMS updates the production schedule every

week to sequence the release of a week’s

worth of orders. Every machine entering the

final assembly line is given a sequence identity

number.

An important by-product of the sequencing

process is the production of delivery

schedules for key components supplied just-

in-time (JIT). Previously these schedules were

accessed by the suppliers using Pc Anywhere

software. This information is now being

updated several times a day and posted as

Web JIT schedules, allowing key component

suppliers the maximum time to respond to

changes in the requirements.

The previous sequencer tool had been

installed five years earlier with the

introduction of the 4200 Series, the precursor

to the 4300 Series of models. This was

superseding the 300 Series and AGCO were

faced with a situation where it was going to be

running three different model platforms for a

time.

‘‘While this system fulfilled our initial

requirement it was very monolithic and it

became difficult to support. It also lacked

capability and we were unable to make any

improvements ourselves’’, explains Henry

Filipiuk, AGCO’s manufacturing and

engineering systems manager. ‘‘We regard

sequencing as crucial to our production

process and we wanted to have more control

over our own destiny.’’

‘‘The solution came with the development

by Tecnomatix Technologies of a

replacement sequencing processor module as

part of its eM-Power range of manufacturing

process management tools. The SGMS

application runs on a high specification PC

that communicates with the company’s

mainframe business management database

via the local area network.

‘‘We now have the best of both worlds. The

functionality we created around the

Tecnomatix Sequencer was developed in

Microsoft Access 2002 and used Access tables

on the PC. As a result, we have a future proof

system which we are able to support and

update to meet new requirements.’’

Additional functionality provided by the

SGMS includes an interface for the

production of assembly documentation.

Other features include calendar displays

related to shift times; tractor commitment

recording as the machine enters the assembly

line; and gap analysis to detail the reasons for

drop outs, the exceptions usually caused by a

major supply shortage. This information can

then be used to provide feedback for remedial

action.

The Tecnomatix eM-Plant software

generates the sequence by following specific

criteria and parameters governing the

engineering content, features and line

capacity as standard hours. Processing starts

with a list of orders of all the tractors

scheduled for delivery within a given week.

From this the software calculates a sensible

starting position and then it runs through

different scenarios trying out different

sequences until it comes up with an optimum

throughput for the factory.

Effectively, each tractor order is weighted

according to its complexity and then

Plate 6 AGCO’s Massey Ferguson tractor factory, in

Coventry

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Volume 22 . Number 3 . 2002 . 283–289

sequenced to ensure the line is supplied with a

manageable workload. This is determined by

a list of features, defining the build

specification. Every feature, or possible

variation in equipment fit, is assigned a

priority ranking number, enabling a total

value for ‘‘complexity’’ to be calculated.

Processing has been improved with the

introduction of a genetic algorithm. This

continues to search for an optimum solution

for as long as it is allowed to run, whereas

previously the system would stop after it had

reached a result that agreed with pre-defined

rules. For additional flexibility, rules can be

applied to bias the throughput of particular

orders, for instance a batch of export orders

being made available by a specific date for

transportation and sea freight arrangements.

On a day-to-day basis the SGMS supports a

busy communications activity dealing with

numerous enquiries relating to programme

management and component deliveries.

Orders are imported into the SGMS

database and a new sequence generated after

a weekly production-planning meeting.

Updates from the shop floor confirm the

launch of each new build in the sequence.

If for some reason the tractor order cannot

proceed to final assembly, the order line can

be removed from the sequence and parked on

the bottom of the screen where it can be seen.

Once the problem has been resolved, the

order is simply re-inserted back into

sequence.

‘‘I have more information available for

handling enquiries and updating the

production status’’, says senior product

scheduler Bill Solloway. ‘‘I can call up the

complete bill of materials for a tractor order at

each level and then drill down through each of

the engineering group units that make up the

specification.’’

The database includes a summary of all the

features for a given range of tractors. From

this the user can select a group and obtain a

count of features and the timing and standard

hours allowed. This feature is useful for

assessing the impact of changes to the

programme.

System utilities enable the user to create

and maintain features. Data such as a list of

features can be attached to specific orders and

this will be flagged up when the order is

imported into the system. Maintenance of

features is used to keep track of design

changes and add specific information, such as

tools or particular assembly requirements for

each feature.

The production process

New build starts with the assembly of rear

axle and gearbox combinations, which are

then held in a buffer store. These are

dispatched to the main assembly hall, by

sequence against a tractor order, as all the

necessary component parts are confirmed as

available. Engines and front axles are added

to form a chassis, which then progresses on to

the chassis paint process. After painting the

line splits into two final assembly tracks, the

primary line handles the larger more

sophisticated models, and the second line

provides an alternative track for the smaller

less complicated machines.

Scheduling procurement – JIT

While the new system has improved the

efficiency on the shop floor the full impact is

still being felt with component suppliers.

AGCO operates a lean manufacturing

strategy with high value items delivered JIT to

meet the production schedule.

‘‘Our aim is to minimise stock holding by

buying today what we intend to use

tomorrow. As a result of this strategy, stock

holding of high value components, such as

engines, has been reduced to about a fifth of

what was considered normal just four years

ago.’’

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Volume 22 . Number 3 . 2002 . 283–289

New products

New Electrox marking lasers

Keyword Lasers

Electrox Scriba machines have long been

regarded as the industry standard for laser

marking. Now, the 600 Group company’s

newly launched Scriba ‘‘plus’’ versions of

these popular Nd:YAG laser markers offer

greater flexibility and productivity than ever

before. Industries served include computers,

telecommunications, electronics, tooling,

medical equipment, giftware, as well as

throughout general engineering (see Plate 1).

The recognised ability of the Scriba family

of laser markers to fit easily into widely

differing production environments for fully-

integrated marking, along with its ease of use,

has now been markedly extended with the

introduction of the new ‘‘plus’’ versions.

Software enhancements derived from the

company’s own internal development

capability enhance the systems in several

ways, including: higher levels of user

friendliness, better compatibility with other

devices and more capacity plus greater

flexibility coupled with ease of use.

Entry level system

Scriba Eplus is an entry level system for the

low to medium volume user that does not

compromise on quality or reliability. Rated at

75W, Scriba Eplus offers marking speeds up

to 3,000mm per second and can put down

1mm high characters at up to 300 per second.

With its newly extended pulse frequency

range Scriba Eplus is capable of marking a

broader spectrum of materials, including

stainless steel.

High performance lamp pumped systems

For high performance applications the 90W

and 120W Scriba II plus, lamp pumped laser

marking systems provide marking at up to

5,000mm per second and are capable of

putting down 1mm high characters at up to

500 per second.

Diode pumped systems

Scriba D40 plus is the 40W diode pumped

implementation of the Scriba concept that

takes advantage of the many benefits of diode

technology. First, diode pumping provides

higher quality marking through better beam

stability and reduced spot size. Integrated

chillers reduce the hardware footprint while

direct connection to single phase (domestic-

type) electricity supply simplifies installation –

and with diodes guaranteed at 10,000 hours,

Scriba D40 plus offers improved reliability

and lower maintenance.

Flexibility and productivity

Both Scriba II plus and Scriba D40 plus are

available as twin head models – Scriba II Duo

plus and Scriba D40 Duo plus – which have

two marking heads to give the ultimate in

speed and throughput.

For further information: Ray Gawn, Sales

and Marketing Director, Electrox, The

Business Park, Letchworth, Herts SG6 2HB,

UK. Tel: +44 (0) 1462 472400; Fax: +44 (0)

1462 472444; E-mail: ray.gawn@electrox.

com

Lambda Photometrics catalogue

Keyword Positioning

Lambda Photometrics announces the

availability of the new PI Nanopositioning,

Micropositioning and NanoAutomation1

catalogue (see Plate 2).

The publication is a comprehensive guide

to the piezo, motorised and manual

positioning products manufactured by PI.

Details provided include information on a

Plate 1 The new Scriba Eplus entry level laser marking

system from Electrox

290

New products Assembly Automation

Volume 22 . Number 3 . 2002 . 290–295

new automated six axis positioning system

with sub micron resolution for MEMS and

fibre device manufacturing, multi axis piezo

stages with nanometer resolution for

semiconductor and microscopy work and

motorised and piezo driven actuators for a

range of industrial applications. The

catalogue is also a reference book, providing

extensive applications information, as well as

technical data on the theory of piezo

positioning and the fundamentals of

mechanical micropositioning.

To obtain your copy please contact

Lambda Photometrics by phone on: +44 (0)

1582 764334 or by E-mail: info@lambda

photo.co.uk.

CD explains machine safety control

Keyword Safety

A CD providing comprehensive and up to

date information about machine safety

control is now available from Omron

Electronics (see Plate 3).

Designed to provide important information

quickly and efficiently the presentation is

broken down into a number of sections and

subsections so that navigation is

straightforward.

The first section looks at the ever-changing

legislation surrounding machine safety

control. Subsections are dedicated to machine

safety, risk assessment and safety control

systems, with each being reviewed in concise

and clear terms so that engineers can be

certain that they are taking the most suitable

approach to every safety issue.

Other sections are each dedicated to a

particular technology in Omron’s

comprehensive range of safety products,

including light curtains, switches and relays.

Basic information, application functions and

selection procedures are detailed for each

technology.

The CD includes complete data on all

Omron safety products, contact information

and an overview of the company.

For further information, please contact:

Mandy Smith at Omron Electronics Ltd,

1 Apsley Way, Staples Corner, London

NW2 7HF, UK. Tel: +44 (0) 20 8450 4646.

New, pre-engineered, multi-axis,handling and assembly technologysystems save design and assembly time

Keywords Pneumatic, Robots, Assembly

Now, the configuration of 2- and 3-axis

pneumatic systems for cantilever, Cartesian

and gantry-style handling and assembly

machines is easier than ever, with the

introduction of Festo Corporation’s new

Handling and Assembly Technology (HAT)

(see Plate 4).

HAT offers machine builders an alternative

to traditional methods of developing handling

and assembly equipment, which, in the past,

required the integration of custom structural

components, selected motorized actuators,

expensive electronics, and long hours of

engineering and integration. HAT is a

modular solution, offering three pre-

engineered and totally pneumatic options that

reduce not only the design and engineering

time, but also provide excellent performance

at lower prices than custom motorized or

other pneumatic systems.

Plate 2 New PI catalogue Plate 3 A CD providing comprehensive and up to date information about

machine safety control is now available from Omron Electronics

291


Volume 22 . Number 3 . 2002 . 290–295

The pick and place system (y-z configuration)

is standardized around two pneumatic

actuator designs, which are used to meet

small, medium and large load applications.

Festo’s SLT actuator, featuring caged roller

bearing guide and integral pneumatic piston,

is designed for direct mounting to another

SLT to for a precision y-z combination with

strokes of 100 6 50mm and thereby

constituting the company’s ‘‘small’’ pick and

place option.

The ‘‘mid-sized’’ and ‘‘large’’ pick and place

options consist of combination axes,

including the SLT and a uniquely designed

pneumatic linear actuator, HMP. The HMP

features precision linear motion and the

ability to perform intermediate positioning

along the 100mm stroke. The piston rod

extends and retracts very accurately due to

constant support geometry established by two

pairs of opposing bearing that are preloaded

against precision ways ground into the rod,

guaranteeing accurate linear displacement,

and excellent resistance to torsion loads.

Festo’s gantry (2-axis) and cantilever (3-

axis) systems meet the needs of x-z and x-y-z

handling and assembly applications with the

implementation of the SLT or HMP (z axis),

HMP (servicing cantilevered y axis loads) and

the low profile SLG or DGPL serving as the

cross (x) axis. The SLG and DGPL are both

designed to span the vertical supports

(DGPL, a rodless pneumatic actuator,

requiring no structural support element in

500mm stroke, due to its extruded aluminum

housing and rigid guide design). The SLG

offers excellent resistance to rotational

deflection, since its low profile base and offset

recirculating guide bearing system place the

centerline of thrust very near the z axis

attachment point.

Gantry configurations requiring long z-axis

stroke (up to 100mm) employ the HMP and

tandem DGPL cross axes actuators that

greatly reduce the effect of rotational load

moments caused by of heavy loads and longer

strokes.

The supporting structure for all of the pick

and place units is constructed with pre-

engineered structural extruded aluminum

beam components, and assembly hardware

that provide the necessary strength and

orthogonality for pre-engineered easy

assembly. This pre-engineered concept saves

considerable design and assembly time.

While custom systems utilizing these

components are available to service

applications with specification outside the

standardized configurations, easy-to-install

HAT pre-engineered solutions are ideal for

applications such as assembling, transferring,

palletizing, and insertion of parts/tooling of

up to 5kg, with a positional accuracy from

0.01 to 0.02mm.

Festo Corporation offers a broad range of

products and services to provide cost-effective

solutions to fulfil automation requirements.

Festo offers worldwide sales and engineering

support, with subsidiaries in 52 countries, and

distributors in over 180 countries.

For more information, contact: Scott

Schuler, Festo Corporation, 395 Moreland

Road, Hauppauge, NY 11788, USA. Tel: +1

(631) 435-0800, ext. 383; E-mail: info@

festo-usa.com http://www.festo-usa.com

Increase production and improvemachining accuracy with new multi-holdspeed-release clamps from WDS

WDS has introduced a new range of powerful

double edge clamps that feature a simplified

and extremely fast method of fixing and

releasing multiple components on machine

beds (see Plate 5). The range includes several

different types of clamp aimed at providing a

fast and flexible solution for clamping any

item from complex machined shapes with

high finished surfaces to rough cut billet and

castings. Models are available with soft jaws

for easier customisation, threaded jaws for

applying specialist gripper and a useful

positive pull down clamping action.

There are five models in the range, each one

can be adjusted and secured using just one

central fixing bolt to extend or retract a pair of

sprung jaws. The jaws move in tandem to

allow quicker fixing and easier releasing of

multiple components. Measuring between

Plate 4 Festo’s Handling and Assembly Technology

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Volume 22 . Number 3 . 2002 . 290–295

31mm and 67mm across at full expansion, all

the clamps are extremely compact, providing

maximum space on the machining bed for

multiple components.

The range can provide up to 9,000kg of

holding force, providing complete stability for

the work piece and ensuring high machining

accuracy. The high clamping force also adds

to the safety of machining operations,

especially under pressurised working

environments where machine tools are

working at high speeds and feed rates.

Hardened to 52 HRC (Hardness in Rockwell

C), the heat-treated jaws come with a serrated

contact surface, providing excellent clamping

for rough-cut stock and castings.

As part of the range, WDS has introduced a

‘‘twin wedge’’ clamp that firmly grips the

components to be machined and

simultaneously pulls the work pieces down

against the guide frames. Standard low

profile, single wedge clamps are also available

with smooth jaws that allow for three-

directional machining. The units can come in

sizes as small as 27mm across, which can still

provide up to 1,500kg of holding force. Their

small size and robust design allows for quick

set-up times and increased production due to

greater numbers of components on

automated machining beds.

For awkward component shapes and

softer materials such as brass, aluminium

and plastic, there is the soft jaw clamp.

Available with smooth jaws that are

hardened to HRC 30-34, the soft jaw model

has been designed for custom machining of

surfaces to suit the geometry of the work

piece and allows a variety of different

components to be held on the same machine

bed.

In order to fix a broad range of materials on

the same bed, a double-edged clamp with

tapped jaws can be supplied that

accommodates any custom holding pad

without needing to permanently alter the

main fitting. Combinations of odd shapes or

materials can also be quickly secured and

released by using the double-edged clamp

with ball bearing gripper. Working on the

same principle, the ball bearing gripper allows

for precision holding and features the same

cross-wedge construction as other models,

allowing for firm locking in every direction.

Enquiries: Peter Heselton, Marketing

Manager, WDS, Richardshaw Road,

Grangefield Industrial Estate, Pudsey, Leeds

LS28 6LE, UK. Tel. +44 (0) 113 2909852;

Fax: +44 (0) 845 6011173; E-mail:

[email protected]

Customised process machinery demandscustomised belt drives

Keywords Steel, Automation

Harro Hofliger, a leader in the field of process

automation and packaging technology,

incorporates steel belts supplied by Belt

Technologies Europe into its battery

laminating machines (see Plate 6). These are

used throughout Europe by some of the

leading laminators. The company also relies

on Belt Technologies for belts which are used

Plate 5 A new multi-hold speed-release clamp from

WDS

Plate 6 Steel belts from Belt Technologies Europe are

incorporated into customised packaging machinery

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Volume 22 . Number 3 . 2002 . 290–295

by world leading pharmaceutical products

manufacturers within their packaging

machines.

Battery laminating machines are custom

built by Harro Hofliger to order. They have

sourced steel belts from Belt Technologies for

over three years with purchases increasing

year on year. The success of the partnership

has been based upon Belt’s ability to supply

customised steel belts at short notice,

enabling Harro Hofliger to meet its tight

delivery schedules.

All the belts supplied are coated and

non-stick, manufactured from a grade of

Teflon. This specification is essential as the

laminating process produces a sticky residue

which could have a detrimental effect on the

performance of any other type of drive

system.

Steel belts, 300mm wide, are usually

supplied, although there have been

requirements for different dimensions. Other

benefits of steel belts important to Harro

Hofliger include the precision positioning that

can be attained so that the batteries are in

exactly the right place on the line to be

laminated.

For pharmaceutical products packaging,

Harro Hofliger can again provide customised

machinery as well as replacement parts.

Typically, precisely perforated belts are

purchased from Belt Technologies. The

shape, the angles of the perforations and the

repeated pattern along the length of the belt

provide the precision positioning required

when pharmaceutical products are packaged

at very high rates without operator

interruption. Options such as different belt

coatings and vacuum belts are also often

specified.

Contact: Brian Harbison, Belt

Technologies Europe, Suite 3L, Durham

Mountjoy Research Centre, Stockton Road,

Durham City DH1 3UR. Tel: +44 (0) 191

3831830; Fax: +44 (0) 191 383 1820.

National Instruments new MotionAssistant2 accelerates motion controldevelopment

Keyword Motion control

Engineers and scientists now can use National

Instruments Motion Assistant, a new

development tool that automatically generates

LabVIEW code and improves development

productivity. This tool helps build

applications that use motors and positioning

devices and is for use in a variety of

applications ranging from biotech laboratory

research to optoelectronics manufacturing

(see Plate 7).

With NI Motion Assistant, users can also

quickly develop code recipes for Microsoft

Visual Basic and Visual C++ with

Measurement Studio, National Instruments

set of fully integrated measurement

components. Combined with either

LabVIEW or Measurement Studio, Motion

Assistant helps engineers create motion

applications ranging from simple single-axis

motions to demanding multi-axis motions.

With the NI Motion Assistant point-and-

click interface, engineers and scientists can

quickly program and prototype motion

systems to reduce development time. This

new development tool deploys prototypes into

applications and easily adds special

placeholders for integrated components such

as vision or data acquisition. NI Motion

Assistant also works with NI motion

controllers for open or closed-loop motion

control and interactive creation of each co-

ordinated point-to-point, circular, or

contoured move in the sequence.

For more information contact NI. Tel:

(01635) 523545; Fax: (01635) 523154;

E-mail: [email protected]; www.mi.com/uk

Plate 7 National instruments new Motion Assistant2 is a flexible and

easy-to-use development tool for building and prototyping motion

applications. Combined with LabVIEW2, LabWindows2/CVI, or

Measurement Studio2, engineers and system integrators can use this

software tool to create a development environment for motion

applications ranging from simple single-axis motions to demanding

multi-axis motions

294


Volume 22 . Number 3 . 2002 . 290–295

New T-LAM2 stator design adds35 per cent extra torque to convenienceand flexibility benefits of integratedlinear actuators

Keyword Activators

The off-the-shelf convenience and flexibility

of INMOCO’s SR series of integrated linear

actuators is being complemented by increased

torque performance, following the

introduction to the range of new T-LAM2

(see Plate 8) segmented stator technology.

The T-LAM design enables 35 per cent more

continuous motor torque to be provided from

the same frame sizes as existing SR series

units, with no cost premium.

The improved torque performance (up to

9.31Nm) and efficiency of the SR Series units

are the result of a design harnessing the

combination of high-density Neodymium

iron boron magnets and the limited heat

generation qualities inherent in the new

T-LAM segmented stator design. In

particular, the elimination of end turns in the

stator, and the use of thermally conductive

potting removes the parts most susceptible to

failure in a traditional stator. The design also

benefits from interface insulation against the

high voltage and currents of today’s servo

drives, and from class H insulation that

complies with UL requirements.

The SR Series is similar in design to

INMOCO’s more highly specified GS series

of linear actuators, but with a reduced subset

of features at a lower cost. As such, the range

offers the ideal solution in applications where

competitiveness is a key concern, and where

the options and/or dynamic load

performance/ life of a GS actuator are not

really required.

Optimising the SR design in this way means

that the units are competitive with low cost

ball screw actuators, but, importantly,

provide two to three times the life of the latter

units, when compared size-for-size.

Despite their overall lower cost, the SR

series actuators still benefit from Exlar’s

patented and well proven inverted roller screw

mechanism, as the means of converting rotary

motion, from a brushless servo motor, into

high speed, high thrust linear motion.

The mechanism has a lead accuracy of

25mm/300mm for high precision operation,

and offers nominal backlash of 0.10mm. It is

designed into compact 84mm or 99mm frame

sizes, to produce packages that offer users a

range of strokes from 40mm to 305mm, force

ratings up to 9619N and linear velocities to

635mm/sec.

Selection of the suitable feedback medium

(encoder with MS-style connectors) offers the

advantage of enabling the SR Series actuators

to be powered by nearly every brand of

brushless motor amplifier on the market. This

flexibility allows SR Series actuators to be

incorporated into the highest performance

single and multi-axis motion control systems

in use today. In applications varying from test

rigs and semi-conductor manufacturing, to

aircraft assembly, the SR Series of actuators

show incredible performance and durability.

The task of mounting the SR Series

actuators is simplified by the tough, square,

anodised aluminium housing, which is sealed

to IP54. The design lends itself both to front-

flange or rear clevis mounting. In addition to

security in mounting, the integrity of the

assembly, both in terms of environmental and

‘‘noise’’ terms, can be optimised with the

option of moulded, shielded cables.

For further information contact: Gerard

Bush, Sales Application Engineer, INMOCO

Limited, 4 Brunel Close, Drayton Fields,

Daventry, NN11 5RB, UK. Tel: +44 (0)

1327 300320. Fax: +44 (0) 1327 300319.


Plate 8 New T-Lam2

295


Volume 22 . Number 3 . 2002 . 290–295

Internet page

Keywords Computer software, Assembly,

Design, Internet

http://www.immdesign.com/Immersive Design, Inc.

Immersive Design develops and markets 3D

interactive software and applications for

improving the product development and

service process. It aims to provide

manufacturing organisations with the ability

to increase understanding of product design,

assembly, repair and maintenance through

the use of Web-based interactive animation.

http://www.silma.com/SILMA

Founded in 1983 and merged with Adept

Technology in 1995, SILMA is a leading

supplier of software for computer simulated

manufacturing technology. SILMA brings

automated equipment programming out of

the factory and puts it on the programmer’s

desktop, providing tools to create, optimise

and test equipment programs without

affecting manufacturing schedules or

production. Its products help manufacturers

maintain their competitive edge by shortening

design to manufacturing cycles, increasing

productivity and reducing costs. The SILMA

product line includes off-line programming

solutions for robots and coordinate measuring

machines (CMMs); assembly process design,

simulation, and analysis tools; and a powerful

3D virtual robot and cell simulator, focusing

on small parts assembly and material handling

applications.

http://www.delmia.com/Dassault Systemes – DELMIA

Dassault Systemes offers extensive process

planning and simulation tools that enable

companies to develop an optimal process for

their manufacturing needs. DELMIA is a

unified brand and a consolidated company

devoted to eManufacturing.

Overall, this is a rather poor Web site but

one that contains plenty of corporate and

product information.

http://www.mscsoftware.com/MSC.Software Corporation

MSC was founded in 1963 and introduced

structural analysis by digital simulation of

analogue methods (SADSAM), the

forerunner of MSC’s flagship program,

MSC.Nastran. MSC.visualNastran 4D is a

Windows1 based engineering tool ideal for

the mechanical engineer who designs

products with moving components. This

application merges motion and stress analysis

into a single functional modelling system,

allowing engineers to test the dynamics of

their assemblies before manufacturing and

without building physical prototypes. It

provides simulation technology and services

to a broad spectrum of industries including:

aerospace, automotive consumer products,

computer and electronics manufacturers and

universities. It is focused on Web-enabling its

products through Engineering-e.com (http://

www.engineering-e.com) and uses the core

strengths, competencies and infrastructure of

MSC.Software to create the engineering

marketplace on the Internet.

This is a very good site that is well worth

visiting.

http://www.3dcs.com/index.htmlDimensional Control Systems, Inc.

Dimensional Control Systems Inc. is a world

leader in dimensional management. It is

committed to developing leading-edge

technology in dimensional engineering.

http://www.designtechnologies.com/Mechanical Dynamics

Founded in 1977, Mechanical Dynamics is an

international supplier of virtual prototyping

solutions. Its ADAMS1 software is used to

build and test functional virtual prototypes of

complex mechanical system designs in the

automotive, aerospace, rail, and machinery

industries.

This is another good Web site but one that

is difficult to navigate.

http://www.alibre.com/public/Alibre, Inc.

Alibre Design is a low-cost, lightweight,

Internet based mechanical CAD and

296

Internet page Assembly Automation

Volume 22 . Number 3 . 2002 . 296–297

data-sharing application that helps

manufacturers improve design and

manufacturing processes by extending them

to all possible enterprise and supply chain

participants. The peer-to-peer (P2P)

architecture allows users to simultaneously

share, create, modify and discuss 3D models

and 2D drawings in real time. Therefore,

OEM and supplier design teams can work

together in real-time, securely accessing,

sharing, and generating precise 3D design

data.

Overall, this is a simple Web site for an

impressive product.

HOT SITES

http://www.dfma.com/Boothroyd Dewhurst, Inc.

Boothroyd Dewhurst, Inc. was established in

1982 and is a market leader in product design

review software. Its major product is the

design for manufacture and assembly

(DFMA) software, which can help customers

reduce manufacture and assembly costs,

improve quality and speed time to market.

The DFMA software integrates the design for

assembly software (DFA) – a systematic

approach to design review used to simplify the

structure of a product and reduce

manufacturing costs, and the design for

manufacture (DFM) early cost estimating

software – used to estimate material costs,

process times, tooling costs and secondary

operation costs for components. Design for

service and design for environment are also

available and enable complete design review

through the product development cycle.

http://www.tecnomatix.com/Tecnomatix Technologies, Ltd

Tecnomatix Technologies, Ltd is a provider

of manufacturing process management

software to the electronics, automotive,

aerospace and heavy equipment industries. In

1983 Tecnomatix launched its proprietary

computer-aided production engineering

(CAPE) tools to help manufacturers fully

computerise the industrial process and

achieve a seamless transition from design to

production. In March 2000 eMPower was

launched and is an open platform of software

applications providing a collaborative

environment for authoring, simulating and

optimising manufacturing processes across

the extended enterprise. eMPower supports

the entire manufacturing process life cycle

from process planning and detailed

engineering to mass production. Web-based

tools enable communication and exchange of

manufacturing process information

throughout the enterprise, its plants and

suppliers.

Its customer base includes companies such

as Motorola, BMW, General Motors, Airbus,

and Boeing.

This is a superb Web site that is also

available in French, German, Swedish and

Japanese. Brochures detailing solutions for

the automotive, electronics and aerospace

industries can be downloaded from the site.

Jon Rigelsford

297

Internet page Assembly Automation

Volume 22 . Number 3 . 2002 . 296–297

Book reviews

Engineering Document ControlHandbook 2nd ed.

F.B. Watts

American Technical Publishers Ltd

2000

376 pp.

ISBN 0-8155-1446-8

£53.00 (hardback)

Keywords Engineering, TQM

This book stresses the importance of

configuration management (CM) and

engineering documentation control

(EDC) on the road to successful world class

total quality management (TQM). It aims

to bridge the gap between design

engineering and the rest of the corporate

world.

Chapter 1 introduces CM and its history.

The managers job, documentation control

functions, CM functions, and organisation

with CM, are also discussed. Chapter 2,

Product documentation, addresses topics

including: documentation and standards, the

body of a part drawing, document signatures,

and specification control and source control

drawings.

Identification numbers, and

interchangeability are discussed in chapters 3

and 4 respectively. Topics addressed include:

product and model number, traceability,

revision number and levels, spare parts and

assemblies, and PCB interchangeability. Bills

of materials (BOMs) are presented in

chapter 5 and address data responsibility,

parts list and BOMs, 100 per cent BOM

accuracy, MRP/phantom solutions, and

modular designs.

Cross-functional teams, responsibility,

nonconforming material, and ISO/QS/

AS 9000 are amongst the topics discussed in

chapter 6, while chapter 7 addresses Product

and document release. The following three

chapters discuss Change requests, Change

costs, and Change control respectively.

Topics addressed include: reliability and

other test data, production problems, costing

a change, design and development costs,

types of change, advanced document change

notice (ADCN), effectively, and tracking the

change.

Chapter 11, Fast change, addresses why

process speed is important, while Process

standards and audits are presented in chapter

12. Benchmarking is discussed in chapter 13

and includes surveys and examples and

techniques for benchmarking. The final

chapter of the book addresses CM in the

Future and provides a summary of the key

ideas discussed in the text. References and a

recommended reading list are also provided.

Overall, the Engineering Documentation

Control Handbook provides clear and simple

coverage of how configuration management

can enhance small and large companies alike.

It will be of interest to engineering managers

and executives, manufacturing engineers,

production control and QA managers,

planner-buyers, and field service personnel.

Automation, Production Systems, andComputer-integrated Manufacturing2nd ed.

M.P. Groover

Pearson Education – Prentice-Hall

2001

856 pp.

ISBN 0-13-088978-4

£38.99 (hardback)

Keywords Automation,

Computer integrated manufacturing

This book is primarily aimed at advanced

undergraduate and first year graduate

engineering students. It is also suitable for

practising engineers and managers who wish

to learn more about automation and

production systems in modern

manufacturing.

Chapter 1 provides an introduction and

overview of the book, while Manufacturing

Operations are discussed in chapter 2. The

remaining 25 chapters are divided into five

parts.

Part I addresses automation and control

techniques. Six chapters are included and

present an introduction to automation;

industrial control systems; sensors, actuators

and other control system components;

numerical control; industrial robotics; and

discrete control using programmable logic

controllers (PLCs) and personal computers.

Part II, Material Handling and

Identification Technologies, discusses an

introduction to materials handling; material

transport systems; storage systems; and

automatic data capture respectively.

298

Book reviews Assembly Automation

Volume 22 . Number 3 . 2002 . 298–299

Chapters 13 to 19 combine to form Part III,

Manufacturing Systems. Subjects presented

in this part include: single station

manufacturing cells; group technology and

cellular manufacturing; flexible

manufacturing systems; and automated

assembly systems.

Part IV, Quality Control Systems, includes

four chapters which introduce quality

assurance and discuss statistical process

control (SPC); inspection principles and

practices; and inspection technologies. The

final part of the book addresses

manufacturing support systems. Topics

covered in this section includes product

design and CAD/CAM in the production

system; process planning and concurrent

engineering; and lean production and agile

manufacturing.

Automation, Production Systems, and

Computer-Integrated Manufacturing is a

textbook which should be read by at least one

member of a manufacturing organisation. Its

many equations, example problems,

diagrams, end-of-chapter exercises and

historical notes, help make it suitable for both

engineers and managers.

The Entrepreneurial Engineer:Starting Your Own High-Tech Company

R.W. Fields

Artech House

1999

332 pp.

ISBN 1-58053-029-X

£46.00 (hardback)

Keywords Entrepreneurs, Engineering

The Entrepreneurial Engineer: Starting Your

Own High-Tech Company helps practising

engineers and other technical people turn

their product idea into a successful high-

growth, product oriented company. The book

highlights the many pitfalls that cause a

business development to fail. It emphasises

the fact that every facet of a company is of

prime concern and must be dutifully mastered

and carefully thought out.

The book comprises 14 chapters divided

into four parts. Part I provides an overview of

business development and teaches a mental

set best suited to designing, building, and

carrying out the targeted business

development effort. Chapter 1 describes a

view of the overall process, while success

factors and the stages of business

development are discussed in chapters 2

and 3.

Part II addresses Professional Planning and

Funding. The four chapters in this section

discuss the (product) concept, strategic and

tactical planning, the business plan, and

funding. Part III, Product Design and

Launch, analyses the research and

development stage, the design stage, the

launch preparation stage, and the product

introduction stage.

Part IV, Building Long Term Value, is the

final part of the book and focuses on

designing and developing the company to

optimise long-term value. It assumes that the

company has completed the introduction

stage of business development and is ready to

enter the stabilisation and growth stage.

Stabilisation and growth are the focus of

chapter 12, while chapter 13 addresses

Control: making it happen. The

Entrepreneurial Engineer concludes with a final

overview in chapter 14. Appendix A extends

the formal business plan and Appendix B

features a real-world example of proper

business development. The book also

includes a comprehensive suggested reading

section.

The Entrepreneurial Engineer: Starting Your

Own High-Tech Company is an inspiring

handbook which is essential reading for any

technically minded person who wishes to

convert a product idea into a marketable

commodity.

Jon Rigelsford

299

Book reviews Assembly Automation

Volume 22 . Number 3 . 2002 . 298–299

Patent abstracts

Computer pre-tensioning simulation

Keywords Simulation, Patents

Applicant: Hibbitt, Karlsson and Sorenson, Inc., USA

Patent number: US5,920,491

Publication date: 6 July 1999

Title: Computer Process for Prescribing an Assembly Load

to Provide Pre-tensioning Simulation in the Design

Analysis of Load-Bearing Structures

This relates to the analysis and design of

structural integrity of structures via computer

implemented simulation. The invention

simulates the tightening of fasteners that are

used to assemble a structure using a

pre-tensioning capability.

In accordance with one embodiment of the

invention, a computer implemented process

simulates the application of a tension force in

an element of an assembly. The process

defines a finite element model for the

element, and creates a pre-tension surface in

the finite element model of the element for

applying the tension force. Conditions are

prescribed relative to the pre-tension surface

for applying the tension force in the

simulation. The conditions include

prescribing an assembly load which includes

either a tension force or a tightening

adjustment. The assembly load is then

applied to the pre-tension surface of the

element to simulate the tension in the element

of the assembly. The results of the simulation

are then evaluated for structural integrity, and

subsequent structural redesign is performed

when necessary.

Feature-based assembly

Keywords Assembly, Patents, BAE Systems

Applicant: BAE Systems Plc, University of Warwick, et al.,

Great Britain

Patent number: WO0116658

Publication date: 8 March 2001

Title: Feature Based Assembly

This patent presents a method for the design

and manufacture of an assembly of

components. This practical approach to

feature-based assembly captures important

component relationships within the design

and subsequent assembly and can provide

extremely beneficial tolerance management in

aircraft OEMs and the supply chain.

The method includes the steps of

identifying potential key characteristics and

carrying out a risk assessment for variation of

the potential key characteristics based on four

values. These values are the probability of

failure or variation; the severity of the

variation; the detectability of the variation;

and the repairability of the variation. Scores

attributed to each value may then be

multiplied together to produce the risk

assessment.

Once the key characteristics have been

selected, process of feature identification and

classification may be carried out, followed by

establishment of assembly precedence of

features for that key characteristic.

Design of microelectronic process flows

Keywords Microelectronics industry,

Texas Instruments Inc., Patents

Applicant: Texas Instruments Inc., USA


Publication date: 30 October 2001

Title: Design of Microelectronic Process Flows for

Manufacturability and Performance

This patent describes a method for improving

device design and process flow design in the

fabrication of semiconductor devices. It

provides a method for simultaneously

optimising and trading off manufacturability,

performance and reliability criteria during

device and process flow design and

performing these functions online or offline.

The method can minimise the impact of

manufacturing variations on semiconductor

manufacturing by statistical design which

seeks to reduce the impact of variability on

device behaviour. It is based on a Markov

representation of a process flow which

captures the sequential and stochastic nature

of microelectronics manufacturing and

enables the separation of device and process

models, statistical modelling of process

modules from observable wafer states and

approximations for statistical optimisation

over large design spaces. The statistical

estimation component of this method results

in extremely accurate predictions of the

variability of transistor performance for all of

the fabricated flows. The statistical design can

reduce parametric yield loss which occurs

when functioning devices do not meet

300

Patent abstracts Assembly Automation

Volume 22 . Number 3 . 2002 . 300–301

performance or reliability specifications.

Parametric yield loss is caused by processing

variations during manufacturing. Statistical

optimisation results in devices that achieve all

transistor performance and reliability goals

and reduces the variability of key transistor

performances.

Fraction defective estimating method

Keywords Estimating, Patents

Applicants: A. Masaaki, M. Seii, K. Takashi, S. Tatsuya and

O. Toshijiro, Japan

Patent number: US2001047218

Publication date: 29 November 2001

Title: Fraction Defective Estimating Method and System

for Estimating An Assembly Fraction Defective of An

Article

A method and system for evaluating qualities

of articles which are manufactured by

assembling constituent parts is presented.

The method and system estimate an

assembling-related fraction defective

coefficient of an article at a stage of design.

Assembling operation, properties/conditions

of parts to be assembled and conditions of an

assembling shop having significant influence

to the likelihood of occurrence of failure in

assembling work are inputted as data. The

articles may be domestic electric/electronic

equipment, products for office automation, or

something similar.

The present invention is concerned with a

fraction defective estimating method for

estimating likelihood of occurrence of failure

in the works involved in assembling an article,

and a system for carrying out the fraction

defective estimating method. The system

comprises a storage medium for storing the

data, information and program for executing

the method. The estimated value of

assembling-related fraction defective is

arithmetically determined with high accuracy

by executing an assembling-related fraction

defective value estimating program on the

basis of the data as inputted

Automatic manufacturability evaluationsystem

Keywords Manufacturing, Hitachi Ltd, Patents

Applicant: Hitachi Ltd, Japan


Publication date: 10 February 1998

Title: Automatic Manufacturability Evaluation Method and

System

A system for evaluating quantitatively at the

design stage of an article whether or not the

article can be realised easily at the

manufacturing stage. The system selectively

determines the best structure from a plurality

of design plans through comparative

evaluation.

The system includes a client machine and a

server machine. The client machine includes

a unit for generating information for guiding

operations of a user, an input device for

allowing the user to input commands and

data, and a display unit. The server machine

includes a registering unit storing user defined

evaluation elements, an index calculating

module for indicating degrees of difficulty/

ease of work, an evaluation element

estimating module, a part workability

evaluation module, an article workability

evaluation module, and a best design plan

selection/determination module.

Jon Rigelsford

301

Patent abstracts Assembly Automation

Volume 22 . Number 3 . 2002 . 300–301

Diary

Conferences and exhibitions

Key: C = Conference, E = Exhibition,

S = Seminar, W = Workshop

2002

GD200214th Int. Conf. Gas Discharges and theirApplications (C)

1-6 September

Liverpool, UK


Web site: cims-liverpool.com/gd2002

Opto – Ireland (C + E)

5-6 September

Galway, Ireland

Optoelectronics, photonics, imaging, optical

metrology, machine vision, SPIE

Web site: www.spie.org/info/ireland/

EuroSensors XVI (C)

15-18 September

Prague, Czech Republic

Solid state transducers

Tel: +420 2 243 539 45

Fax: +420 2 311 9929


Web site: www.eurosensors.cz

ISHM 2002 (C)Int. Sym. Humidity and Moisture

16-19 September

Taipei, Taiwan

Humidity and Moisture

Tel: +886 3 573 2211

Fax: +886 3 572 4635


Int. Sym. Force, Mass, Torque, Hardnessand Civil Engineering Metrology in theAge of Globalization

24-26 September

Celle, Germany

Tel: +49 (0) 211 62 14-0

Fax: +49 (0) 211 14 575


www: www.vdi.de

Engineering of Intelligent Systems (C)

24-27 September

Malaga, Spain

Tel: +31 184 496 999

Fax: +31 184 421 065


Web site: www.icsc-naiso.org/conferences/

eis2002/index.html

5th CLAWAR (C)

25-27 September

Paris, France

Climbing and Walking Robots

CLAWAR

Tel: +33 1 46 54 86 53

Fax: +33 1 46 54 75 80


Web site www-drt.cea.fr/clawar2002

SIMS 2002 (C)Simulation and Modelling

26-27 September

Oulu, Finland

Finnish Society of Automation

Tel: +358 201 9812

Fax: +358 201 9812 27


Web site: www.automaatioseura.fi

IROS 2002 (C)Int. Conf. Intelligent Robots andSystems

30 September-4 October

Lausanne, Switzerland

Web site: http://IROS02.epfl.ch

Frontline Solutions 2002 (C + E)

8-10 October

NEC, Birmingham, UK

End-to-end supply chain solutions

Web site: advanstar.com

ISR 2002 (C + E)Int. Sym. on Robotics

8-11 October

Stockholm, Sweden

Tel: +46 8 782 08 00

Fax: +46 8 660 33 78

302

Diary Assembly Automation

Volume 22 . Number 3 . 2002 . 302–303


Web site: www.vibab.se/swira

Water Jetting (C)

16-18 October

Aix en Provence, France

Tel: +44 (0) 1234 750422

Fax: +44 (0) 1234 750074


Web site: www.bhrgroup.com

Photomec’02 (W)

24-26 October

Louvain-la-Neuve, Belgium

Photonics and mechanics with special session

on sensor systems in mobile robotics

Belgian Society of Mechanical and

Environment Engineering

Fax: +32 2 742 9698


Web site: http://mecarar.fpms.ac.be/bsmee

IFAC Mechatronic Systems (C)

9-11 December

Berkley, California, USA

ISA 2002 (C)

15-18 December

Shanghai, China

Intelligent Systems and Applications

Web site: www.icsc.ab.ca/isa’2002.htm

2003

Materials Testing 2003 (C)

8-10 April

London, UK

British Institute of Non-Destructive Testing

Tel: +44 (0) 1604 630 124

Fax: +44 (0) 1604 231 489


LAMDAMAP ’03 (C)

1-4 July

Huddersfield, UK

Laser Metrology and Machine Performance

Mrs Helene Pickles

Tel: +44 (0) 1484 473266

Fax: +44 (0) 1484 472340


ECC 03 (C)

1-4 September

Cambridge, UK

European Control Conference

Fax: +44 (0)20 7240 8830


Web site: http://conferences.iee.orh/ECC03/

2004

INTERKAMA (E)

16-20 February

Dusseldorf, Germany

www www.INTERKAMA.com

Solutions for automation in production and

Business Processes

If you would like further information about

any of the conferences or exhibitions featured

in the Diary Section, please contact the

organizers for that particular event.

Editorial note: if you are aware of any local,

national or international seminars, exhibitions

or conferences, the Editor would be pleased

to receive this information as early as possible

in order to include it in this section of the

journal.

303

Diary Assembly Automation

Volume 22 . Number 3 . 2002 . 302–303

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