Critical Manufacturing, 2015

MES

ERPvs

Defining MES

Loosening the categories

The case for modular MES

Modular MES in practice

Strategic enterprise integration still matters

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Modern

manufacturing

execution systems

(MES) can deliver the

flexibility to enable

manufacturers to

define the solutions

that meet their

strategic needs.

MES is what you make it:

Define the MES functions

needed, use standards,

consider modularity, and

integrate controls with MES

and MES with enterprise

resource planning (ERP), as

needed.

Strategic enterprise integration

has been in the making for the

past two decades. While much of

the technology to accomplish this

integration is available, the

number of companies actually

claiming to have achieved any

grand integration is few. The first

generation of manufacturing

execution system (MES)

implementations were among the

first technological categories

tasked with providing the glue

that would integrate all parts of

the enterprise and established the

potential of this category.

However, their success was

limited, partially by narrow and

often conflicting definitions of

what MES scope and functionality

actually are. Today, a new

generation of more open, flexible

systems allows manufacturers to

define MES in the way that works

best for their operations.

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Originally written for Control

Engineering Magazine as “Define,

integrate, implement MES with

controls, ERP”

An MES is a dynamic

information system

that drives effective

execution of

manufacturing

operations.

Using current and accurate

data, the MES guides,

triggers, and reports on plant

activities as events occur.

Ideally, an MES is composed

of a set of functions that

manage production

operations from the point of

order release to

manufacturing through the

point of product delivery,

depicting all stages of the

overall production process.

and manufacturing operations

software. They also model which

activities the software can play

and the exchange of

information within

manufacturing operations

systems.

One of the most significant

programs to define MES

technology and its role in

improving manufacturing

excellence was the ISA-95

standard developed by the

International Society of

Automation (ISA), in league with

the manufacturing community

and system suppliers, including

control, enterprise resource

planning (ERP), and MES

providers. (See sidebar at the

end of the story: ISA-95

Enterprise-Control System

Integration, Parts 1 to 6.) ISA-95

addresses MES concepts using

the somewhat broader term of

Manufacturing Operations

Management (MOM), but both

attempt to model the exchange

of information between business

logistics software

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Defining MES

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Figure 1 shows the ISA-95

functional hierarchy of levels of

manufacturing decision making.

At level 4, there are business

planning and logistics decisions,

which are supported by ERP and

supply chain management (SCM)

systems. Level 3 has been where

traditional MES lives, providing

tracking and trending

information to support decisions

in areas such as workflow, recipe

control, and maintenance. At

levels 0, 1, and 2 are decisions

related to real-time production

events, such as process sensing,

manipulation of supervisory

control, and process automation

technology. This is the domain of

distributed control, supervisory

control and data acquisition

(SCADA), and programmable

logic controller (PLC) systems.

Figure 1. ISA-95 functional

hierarchy of levels of

manufacturing decision

making.

In addition to mapping out the

hierarchies of manufacturing

operations, ISA-95 also aims to

improve interoperability among

them, particularly between the

ERP and MES systems. Figure 2

is a compact systems view of the

ISA-95 standard mapped to the

Purdue Reference Model. The

dashed line indicates a possible

border between ERP and the

control system. In the most

typical flow, scheduled orders

pass to the control layer, which

then returns the production

response and capability

information. The standard

describes material, personnel,

equipment, and other

information required for an

effective scheduling model. But

it is critical to note that the

standard does not intend to

dictate exactly which system to

use in which situations. It

provides only neutral guidelines

and data exchange structures

that companies are expected to

adapt to their own situations.

The ISA-95 standard also

provides guidelines for defining

the functional scope of

manufacturing operations

management activity. This

includes definition management,

resource management, detailed

scheduling, dispatching,

execution management, data

collection, tracking, and analysis

as they apply to the production,

maintenance, quality, and

inventory areas. Traditionally,

MES has been viewed as a

translation layer between ERP

(level 4) and the controls and

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automation layer (level 2). In

this role, the purpose of the

MES system is to register and

control-in near real time-all

production orders coming from

the ERP level. It does so by

interfacing with the control

levels to collect and provide

real-time production data and

return all the necessary logistics

and financial relevant data back

to the ERP. But defining the

function of the MES in only this

way does not do justice to its

tremendous potential for

improving manufacturing

productivity, quality, and

flexibility. Its ability to process

real-time data, enforce business

rules, and integrate them with

engineering, quality, and

production workflows make it

the ideal platform for

continuous improvement.

Figure 2. ISA-95 functional hierarchy of

levels of manufacturing decision making.

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Loosening the categories

Realizing the true

potential of MES requires

shifting focus from trying

to define where anything

fits in the categories, to

looking at what is needed

to maximize production

value for the end user.

Ever since the Manufacturing

Enterprise Solutions Association

(MESA) created the first model,

MESA and the industry in

general have acknowledged that

the boundaries between the

different systems which co-exist

in a manufacturing company are

fluid, not rigid. When looking at

the barriers between the ERP

and MES software, for example,

there is a clear overlap among

many functions, such as

planning, order control, human

resources (HR), and maintenance

management, to name a few.

And likewise, there are overlaps

between what might constitute

the activities at the MES level

and at the supervisory control

level (level 2).

A modern analytical framework

can help us determine the

feasibility, the effort and cost, the

flexibility, and the maintainability

of deploying systems at various

levels of the enterprise.

Framework created by

CGI/Logica, for example,

categorizes 15 questions that

can help manufacturers

determine their software needs. (Click here for more information)

The following are examples of

criteria that can be used in

deployment:

• Resolution: What data

resolution is required for

tracking and tracing?

• Response: Does the

operation require real time

data, or can it be processed

in batch mode?

• Configurability: Is the

configuration possible

through out-of-the-box

product features, or does it

require custom development?

• Changeability: Is the

manufacturing process

expected to be stable over a

given period of time, or does

it require frequent changes

and adaption?

Answering such questions guides

the determination of the right

system to implement each of the

MES functions. While the ISA-95

standard makes it clear that such

level-3 functions fit into the

overall MOM scope, it does not

dictate that all shall be

necessarily implemented by a

given MES solution. In fact, for

some segments and for some

industrial contexts, some of

these functions might even be

better fulfilled by the ERP.

The case for modular MES

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Achieving optimal

productivity requires a

mix of functions

performed selectively by

either the ERP or the MES

software.

The ISA-95 standard helps define

such a solution by modeling the

exchange of the information

between business logistics

systems and manufacturing

operations systems and also by

modeling the information

exchanged within level 3 of

manufacturing operations

systems. This implementation

strategy depends, however, on a

critical factor: the existence of a

truly modular MES. More

precisely, it must be possible to

run specific modules without

implementing the complete

application. And it must be

possible to integrate those

modules easily with functional

modules residing in different

applications, including the ERP

software, as well as others.

Rather than functioning as a

monolith covering all possible

functions, the MES must be a set

of modular building blocks, from

which a specific plant can choose

to implement or not according

to its business situation.

In addition to enabling end users

to build their ideal solution, this

modularity helps in the following

ways:

• Scaling: Manufacturers want

to implement functionality

step-by-step, for

methodology reasons or in

accordance to their human or

financial resource capacities.

• Migration: Similar to

scaling, functional modules

need to be introduced step-

by-step, while interacting

strongly with legacy solutions.

• Domain specialization: Despite the wide functionality

set provided by the MES, it

may not include very

specialized requirements

required for some industries.

Modularity is not, however,

something that can be added to

an existing software product. The

solution must be designed for

modularity at inception, through

an architectural or solution-

based framework that remains

open to the later addition of a

variety of solutions.

Another virtue of this more

modular and systematic

approach to software

development is a more generic

system that is more broadly

applicable to manufacturing

challenges in a range of different

industries. It also means that one

is capable of modeling more

complex scenarios that

incorporate very different

processes.

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An interface between

the ERP and the MES

was implemented for a

large integrated circuit

(IC) substrate

manufacturer.

While the project included the

full-scope MES and automation

aspects of a large volume facility,

one of the critical areas was the

interface to the SAP ERP

software. The company uses SAP

R/3 for planning and SAP APO-

Advanced Planning Optimization

for mid- and long-term planning.

The first aspect considered was

the reliability of the interface.

Required for several functional

areas, the interface was bi-

directional and composed of

synchronous and asynchronous

calls. Given the different nature

of systems integrated, however,

particularly in terms of the real-

time and criticality, the

installation required advanced

buffering and error management

techniques.

Buffering was essential because

of significant differences in the

uptime related service-level

agreements (SLAs) of the two

systems. If the ERP is offline for

any reason, the MES could not

stall, because it helped protect

the required 24/7 operation by

buffering calls and then

performing them when the ERP

system was back online.

Advanced error management

was also a must, since the

systems were controlled by

different groups within the

organization and dispersed

geographically.

Changes at the ERP level could

be done, sometimes not

completely considering all the

implications in the different

manufacturing facilities, so

advanced error management

procedures were also of utmost

importance.

Functionally, the data integration

had been performed in different

areas, the following being the

most critical:

• Synchronize material

master data from ERP: The

client's ERP system

maintained the master files

including product information,

bill of materials, flows,

equipment, and production

steps. The target was for this

to be the only source of such

information, so that all

changes made would

synchronize with MES

immediately.

• Production orders: Likewise, production orders

were synchronized from the

ERP into the MES, with the

MES applications reporting

back to the ERP system with

regular and event-based

updates on anything that

impacted order status.

• Engineering orders: Engineering orders were

created at the MES level and

shared with the ERP system.

• Maintenance orders: Because MES applications

track closely to the real usage

of the manufacturing

equipment, it was most

efficient to perform the

maintenance management

functions at the MES level,

including time- and usage-

based events. The

maintenance related

information was sent to the

ERP.

• Material inventory: Material inventory was

regularly updated from MES

into the ERP.

• Warehouse management: Warehouse management was

implemented at the ERP level,

but requests from the shop

floor that impacted

warehouse inventory were

synched with the MES.

• Human resources (HR): Several MES functions

required up-to-date HR

information. This included

potentially critical information

on employee training,

certifications, roles, and

authorizations, etc., that must

be synched regularly with ERP

and MES on HR data.

Modular MES in practice

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Among the most used

functional areas designated by

ISA-95 is the sending of

production schedules from ERP

systems to MES and

synchronizing actual production

status and performance info

back to the ERP. This enables

two-way communication

between corporate level

planning and scheduling to

increase visibility of the

production floor.

Beyond the interfaces

mentioned above, scheduling

interface was implemented for

this client. In this model,

planning and scheduling are

done at different levels, at the

ERP and at the MES, enabling

the combination of the tactical

and operational level scheduling

capabilities. The ERP system

provides infinite capacity

planning based on ship and

start dates. This is then sent into

the SAP Advanced Planning and

Optimizer (APO), which does

finite planning based on

capacity and ship dates, not at

the resource/equipment level,

but at the work-center level.

This high-level rough plan is

then sent to the MES, which in

turn translates it into the

operational plan, considering

additional operational factors.

These include resource

availability and capabilities,

recipe and durable

dependencies, shift

management (employee

availability, qualifications, and

certifications), stock levels, setup

times, preparation and

acclimation times of

consumables, and time

constraints of products and

consumables, beyond manual

prioritizations.

The operational planning, at the

MES level, has a higher

granularity and, based on

additional information, fine

tunes the sequences previously

determined by the higher level

planning done at the ERP level.

Moreover, because conditions

might change at the shop-floor

level, the system reschedules

the operational plan with a

much higher frequency than

what the tactical planning does.

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Strategic enterprise integration still matters

Viewing the MES/MOM space as

much more than a simple

translation layer puts strategic

enterprise management back on

the table. As a control and a

continuous improvement

platform, it enables the

improvements in productivity,

quality, and flexibility that are

essential for competitive survival

in today's hyper-dynamic in

global markets by enabling at

least the following:

• Synchronizing

manufacturing operations

within the supply chain;

• Increasing visibility of the

production plan to

operations and all other

stakeholders;

• Increasing the decision

confidence, helping

everyone to know what to

do when the situation

changes.

These are essential to improve

productivity, quality, and

responsiveness.

MES can boost productivity by

increasing yields and reducing

maintenance and labor costs. It

improves quality, through

monitoring and controlling

production processes and

properly managing

manufacturing exception

processes, while providing

systematic enforcement of

established norms and

guidelines. And it enables faster

reaction to market variations and

contingencies as well as enables

faster introduction of new

products.

About Critical Manufacturing

Critical Manufacturing provides manufacturers in highly-complex environments with a modular, scalable manufacturing execution and intelligence system that enables users to flexibly address market demands, increase efficiency and bolster reliability across the supply

chain while lowering TCO. The company is part of the Critical Group, a private group of companies founded in 1998 to provide solutions for mission and business critical information systems.

www.criticalmanufacturing.com

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