The selection, installationand operation ofCAD systems

by P. E. R. MucciUniversity of Southampton

An introduction is given to CAD in its various forms and the threestages of equipment selection, installation and operation aredescribed. An attempt is made to illustrate the major pitfalls facingboth management and design staff along the way, and it is hopedthat this will help to save both time and money for potential users ofCAD systems. Other aspects which arise from the increased use ofthis new technology, such as security, are also discussed, and finallysome indicators are offered to predict future trends.

Background

Southampton University Faculty of En-gineering has been involved for manyyears in the development and use ofcomputer-aided design (CAD) for indus-trial, research and teaching use. Amajor research programme being doneby the New Technology ResearchGroup (NTRG) in collaboration with alarge local company is studying the ef-fects of a CAD installation on both pro-duct and organisation [1]. Practicalhelp and advice are given on a regularbasis to both small and large companieswishing to invest in CAD systems, andwork is being done on campus todevelop advanced graphics programs,analysis packages and standard data-bases. The Faculty of Engineering has acomprehensive CAD facility of its own,comprising ten alpha and four graphicsterminals accessing a dual VAX mini-computer, nine Hewlett-Packard

graphics computers and two Hewlett-Packard desk-top computers [2].

This facility provides several levels ofCAD capability, including calculation,simulation, analysis, two- and three-dimensional drawing and design. Allworkstations, including the micro-computers, can access the central pro-cessor at alpha or alpha-graphics leveldepending on their status. At presentsoftware is provided by Norrie Hill Ltd.,General Electric Inc. and SwansonAnalysis Ltd.

Introduction

Without doubt the growing use of CADin the engineering industry in recentyears has challenged for the first timethe traditional role of design offices incompany structures. The application ofcomputers to the solution of designproblems, or more specifically to theproduction of engineering graphics, is

Computer-Aided Engineering Journal December 1984

now beginning to influence all stages ofthe design process from conception toproduction in even the smallest engin-eering companies.

The speed of development of CAD islinked directly to the recent growth andadvance of computer technology, andin particular to the improvements in thecost and quality of graphics capability,since the generation, storage and uti-lisation of accurate graphics are the keyto effective CAD. It would be conve-nient at this stage to report that a directproduction advantage could thereforebe claimed, but of course the methodby which, for instance, a new automaticmachine can be justified for the factoryfloor cannot be used to the same ad-vantage in the design office.

The only thing which can be stated isthat the relative cost to users of com-puter systems has dropped sharply inthe last few years, and that when pro-fessional CAD is properly installed andintroduced to staff there is never areturn to old methods [3] .

It is always dangerous to generalisewhere computer technology is con-cerned, but it is now a fair assumptionto say that CAD is no longer only foundin the company with existing computerpower on a large scale; nor is its useand management any more the prov-ince, by birthright, of computer tech-nologists.

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Indeed, much of the current growthin CAD is due to the 'humanising' ofsystems to the state where it is nolonger necessary for the user to haveany preknowledge of computing [4].

There is a large number of CAD sys-tems on the market, and each one isdifferent — even to the extent of usingdifferent terminology to describe thesame thing: the subject is still too newto boast any form of standardisation.However, three groupings can be usedto loosely represent the 'state of theart':

• two-dimensional representation• two-dimensional representationwith automatic projection (two-and-a-half-dimensional representation)• three-dimensional representation.

Whereas two-dimensional represent-ation is an established 'tool' in industry,two-and-a-half- and three-dimensionalrepresentations, although progressingvery fast, suffer limitations at themoment for manufacturing applicationsunless backed up and integrated withtwo-dimensional representation. Sincethe representation of three-dimensionalobjects on flat sheets of paper using asystem of views is a firmly establishedmethod ingrained on the minds of allengineers from an early age, it is likelyto be some time before CAD can elimi-nate all paper in the design process and

be simple and cheap enough to permitdirect transmission of data without theintermediate stage of plotting ontopaper [5].

Applications

By far the most important application ofCAD is the generation of drawings,whether as straight improvements onexisting ones, or by a step-by-step pro-cess from concepts through to calcu-lations, schematic diagrams, layoutsand finally detail design for manufac-ture — computer-aided manufacture(CAM) is not dealt with here, but sufficeit to say that the users of even the mostadvanced CADCAM systems still relyheavily on the traditional 'hard-copy'drawing [6].

In the mechanical industries, the pro-duction of detailed two-dimensionaldrawings provides the bulk of work forthe CAD operator and, although accu-rate statistics are hard to find, this caneasily account for 80% of the availableterminal time, even though prior to in-stallation it may be imagined (or impliedin the supplier's literature) that CAD willbe used for most of the time to 'do'advanced design work hitherto impossi-ble by conventional methods. This is anappropriate point to look a bit morecarefully at what can be expected of aCAD system, and more particularly at

how it can improve efficiency in thedesign process.

First, it cannot be emphasised toostrongly that CAD is an interactive pro-cess and that therefore the computerwill not 'do' anything without a humaninput. It is the ability and level of train-ing of the operator which decides theinput, and it is the quality and reliabilityof the system which determines the effi-ciency of the output. A common mis-conception is that some CAD systems'design' and others just 'draft'. This acci-dent of language which has given ustwo words in the same subject area be-ginning with the same letter has beenthe cause (and the excuse) for muchmuddled thinking over the meaning ofCAD'. Just as it is unlikely that some-body will ever be employed to simplyreproduce sketches or drawings on adrawing board without any personal in-fluence over dimensions or per-formance, so it is unthinkable that anexpensive CAD system would only beused in this way.

Highly accurate detailing and fasteasy modification are two of the mostpowerful 'design aids' provided by CAD,and all professional systems providethese advantages. However, the ideathat a computer program will actuallydo the selection, analysis and graphicalpresentation of any mechanical com-ponent at the press of a button is pure

Fig. 1 Dual-screen stand-alone workstation with high-level drawing/design capabilityShown from right to left: computer with menu screen and keyboard, joystick cursor controller, digitiser board, high-resolution graphicsscreen and high-speed plotter

228 Computer-Aided Engineering Journal December 1984

fantasy, the only sensible place for thevast amount of information associatedwith a particular product is in the mindof the engineer, and a CAD systemshould not be purchased with the ideathat it will eliminate the need for designengineers. It will, however, enable engi-neers to store, retrieve and manipulategraphical data without the need forconstant redrawing and design.

A common view about CAD is that itis only suited to certain fields of engin-eering, but there is often little agree-ment from potential users about whatthese fields should be. Two extremes inmechanical engineering, for instance,are, on the one hand, the manufactureof a wide range of 'one-off' special-purpose machines and, on the other,the mass production of a single productline. In the first case, CAD can providea greatly improved means of keepingdesign changes up to date and consis-tent between the drawing office andthe works, whereas in the second caseit can be used to advantage in themaintenance of quality at minimumcost by standardisation and stock andcomponent control. In both cases, itgives virtually immediate storage andretrieval of data and drawings, and — apoint not to be minimised — providesan excellent means of producing pres-entation material for potential cus-tomers [7].

Presentation material done on CAD isnot just for the benefit of marketing,however: it also provides a very goodway of testing a concept — particularlywhere there are size and shape limi-tations. A CAD 'sketch' can be done toan exact scale, and little effort is neededto work to very close tolerances. Fur-thermore, an ordinary two-dimensionalsystem will produce excellent isometricor orthographic views and a three-dimensional system will, for instance,give true lengths of lines for perspectiveviews, and provide areas and volumesat the touch of a button.

It should not be thought, however,that because a three-dimensionalsystem has these virtues, it can be usedexclusively for all CAD work. At themoment, and probably for a long timeto come, two dimensions will be theworkhorse for engineers designing formanufacture, and this certainly offersthe greatest number of applications ingeneral engineering.

Equipment

From the design engineer's point ofview, the function of a CAD terminal islittle different from that of the tradi-tional desk, drawing board and filingcabinet; the great change is its physicalappearance. The main feature of all

CAD equipment is the screen (VDU)and keyboard which, to a large extent,replace the engineer's pen, pencil,sketchpad and drawing . board. Thescreen and keyboard are connecteddirectly to a computer mounted along-side, or at a distant centralised location.The most up to date systems have (woVDU screens: one displays the designwork and the other displays the variousfunctions available in the form of amenu (Fig. 1).

The operator controls the systemthrough the keyboard and the VDU dis-plays a variety of 'alpha-graphics data'.This means that as well as the numbersand letters available on an ordinarycomputer, a CAD terminal will displaystraight lines and arcs as well. Since akeyboard is not always the best way ofworking with graphics, a digitiser pad isoften added to the terminal, and thispermits a certain amount of 'freehand'sketching and copying to be done, aswell as giving the operator anotheruseful input device for controlling thesystem. A further device often found ata terminal is a 'joystick', which can beused to directly control the graphicsappearing on the screen, so giving theuser yet another degree of freedom. Theaddition of these accessories can be animportant factor in the 'friendliness' ofCAD, since most engineers are more athome controlling co-ordinates with amanually operated cursor on a drawing

board than they are with a typewriterkeyboard. The keyboard, digitiser padand joystick are all ways of manipulat-ing screen graphics so that a finisheddrawing, schematic diagram or designsketch can be created on the VDU. Aplotter is connected to the system sothat a print can be taken from thescreen, and this may either be adjacentto the terminal or elsewhere in theoffice. A printer can also be used which,as well as providing copies of parts lists,calculations etc., may also be able toproduce a quick print of a drawing orsketch for reference purposes.

Returning to the computer itself, alittle more explanation about the typesavailable is in order. Those which aremounted on a desk or table adjacent tothe terminal are called, reasonablyenough, 'desk-tops' and are about thesize of a large briefcase. Those whichare floorstanding and positioned, typi-cally, nearby are called minicomputersor 'minis' and take up the space of, say,a large cabinet. Finally, the large com-puter located in a central area and serv-ing a number of users with differingneeds is a mainframe and can be thesize of a room. It may now appear rea-sonable to further classify them in termsof power and grade them accordingly,but this would be highly misleading be-cause of the vast strides made in recentyears in packing ever more memoryinto ever diminishing spaces. The

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Computer-Aided Engineering Journal December 1984 229

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humble mechanical engineer with noknowledge of computers may be in abetter position to grasp the reality ofthis than the computer technologist,who sometimes hangs on fondly to theconcept of the minicomputer or main-frame as the only real source of poweravailable.

A desk-top computer can now easilymatch a minicomputer in terms of thespeed and storage capability needed torun professional two-dimensional pro-grams, and can 'stand alone' withoutthe need to access another computer(Fig. 2). From the point of view ofgraphics, this offers very fast responseand a high degree of user friendliness. Aminicomputer system which supportsseveral terminals may prove to beslower and less easy to operate, givinglittle independence to the user, and in-flicting all users with its faults (Fig. 3).

Most desk-top computers, and to alarge extent microcomputers as well[8], can, however, be connected easilyto larger computers or share resourceswith other computers and therefore areable to offer the best of both worlds:local high speed, interactive graphics aswell as access to common data. It is notsurprising that many CAD systems nowon the market are designed to do this. Itmeans that each terminal purchasedcan operate independently but, where

necessary, will 'talk to' a minicomputeror mainframe or another desk-top com-puter which already exists in the com-pany (Fig. 4).

Needs

Choosing a CAD system to meet spe-cific current and future needs is not assimple as deciding on a new type ofmachine for the shopfloor or, indeed,updating an existing business computer.The difficulty lies primarily in the ab-sence of any formula to use for assess-ing a cost benefit. First, there may be noprevious experience to draw on withinthe company, and, secondly, CADequipment is usually operated in exist-ing design offices and these are no-torious for eluding accurate costingmethods. A useful approach to assess-ing need is to start with an appraisal ofexisting staff and the amount of timethey spend on fairly .routine tasks likestoring, retrieving and updating draw-ings. A deeper study may reveal a lot ofrepetitive detail and analysis work andspecial customer modification beingdone. At the other end of the scalemuch time may be spent on designschemes to be included in proposals orquotations to clients. If any or all ofthese activities call for regular involve-ment from qualified engineers then

CAD can be considered as offeringmajor long-term advantages. A word ofwarning, however: such a radica)change from traditional practices as theintroduction of this new technologydemands a very high level of personalcommitment from those involved. Amuch repeated comment from sup-pliers and users alike is: 'Without en-thusiasm and interest from staff then noCAD system will work'.

At the current stage of development,CAD should not be considered as away of immediately cutting down staffcosts; the principal need should ratherbe centred around higher design qualityfor products and improved efficiency ofoutput from existing staff. It cannot bedenied, however, that firms startingfrom scratch and aiming to use themost advanced technology would notbuild up a traditional drawing officesystem. Furthermore, evidence is begin-ning to emerge that where CADequipment is introduced into the old-style design office, those who resist itand choose to avoid getting involvedmay reduce their own prospects foradvancement.

Selection

The formation of committees and work-ing parties does not guarantee a focusfor informed technical comment.Indeed, because the introduction ofCAD has such wide implications, cut-ting across traditional departmentalboundaries, it is unlikely that a com-mittee, of itself, could select the correctsystem for a company. At the other ex-treme there are plenty of cases whereselection has been a 'one-man band'and staff have had little say in the pro-cess. Much can be gained from closeobservation of competitors' equipmentand recommendation from long-termusers, and collation of this type of infor-mation makes for a good start, particu-larly if those doing the collating aredrawn from the different interest groupsinvolved. Just collecting the informationcan itself be a mammoth task, espe-cially in the light of the number of sup-pliers of CAD currently in the market,and there is a real danger of becomingswamped with conflicting data.

For a good appraisal of a system, tryto see it operating in the working en-vironment, rather than putting toomuch faith in a demonstration, either atan exhibition or at the supplier's prem-ises. Demonstrations are notorious forgiving the wrong impression of CAD.Either a slick 'set piece' is shown or amass of detail is produced and the pooroperator is bombarded with demandsto do everything except demonstratethe thing which was originally intended.

230 Computer-Aided Engineering Journal December 1984

There is some sense in only seeingthe equipment at the supplier's prem-ises alter first visiting a user — this givesthe opportunity to collect some ques-tions relating to feature(s) of the systemand how it can be applied in specificproduct areas. Conferences are usefulas a general sounding board, if only topick up references to systems not al-ready on the list for future investigation.It is easy, however, to become CAD'punchdrunk', where so much informa-tion is being digested over a shortperiod of time that ordinary powers ofjudgment are somewhat dulled. As thewhole area of this technology is rela-tively new, a lot of small companies areemerging to challenge large corpora-tions for a slice of the business, and,although they are to be viewed with alittle caution, do not dismiss them outof hand. A week is a long time in elec-tronics, and there is much to be said forthe small company in this area whichemploys the latest in established com-puter hardware and is able to quicklymodify and update software to suit par-ticular needs. The disadvantage is, ofcourse, the stability of the companyand its ability to survive and support itscustomers. By the same token, the largecomputer company which has movedinto CAD may be more interested inthe business of selling a large, expensiveand possibly slightly out-of-date com-puter than in improving the quality andefficiency of engineering design work.

This is a suitable time to expand alittle on how CAD is marketed and sup-plied. The three elements of software,hardware and peripherals may either beoffered by one company as, typically, a'turnkey' system, or may be supplied se-parately by different companies. Somevery large multinational computer com-panies can offer all three elements asbeing designed and manufactured bythemselves, or at the other end of thescale a company may offer just thesoftware on its own and leave the pur-chaser to decide on the hardware andperipherals. This latter approach mayhave attractions where a suitable com-puter already exists on site, but greatcare must be taken to assess the pro-jected workload on the machine, sincethe kind of powerful graphics softwarenecessary for CAD takes up much com-puter capacity and needs a lot of speedfor it to run correctly as an interactivepackage.

With the increase in competitionfrom small companies marketing turn-key systems, large computer organis-ations are now beginning to offersoftware support, often by agreementwith a separate company, so that thepurchaser at least has some assurancethat the software has a 'stamp of ap-

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proval' from the hardware suppliers(and vice versa). It is not difficult toimagine the divided loyalties whichsometimes can arise between hardwareand software suppliers, and it is all tooeasy to blame system failures on theother side. Since software costs are afraction of hardware costs, the problemis further complicated by the lack offinancial incentive for the software sup-pliers to spend a lot of time with theuser trying to debug system faults.Therefore, unless purchasers havestrong in-house software capability andintend to develop their own systems,they should avoid too much third-partysupplier involvement, because whenproblems arise after a system has beeninstalled the last thing needed is 'buck-passing'. Ideally a supplier should be sel-ected who can offer direct support forall parts of the system; in other words,it should take front-line responsibilityfor all the equipment, including soft-ware.

The selection process should includesome kind of projection for futureworkloads and applications so that thesystem will be able to cope with an ex-pansion of need. All computer supplierswill offer 'expansibility' and claim thattheir system can support a givennumber of terminals, but care should betaken to avoid the complexity and

expense of too many future 'add-ons',while at the same time acknowledgingthat a modest expansion should beachieved without too much strain onthe system. In this context, and referringback to previous comments on stand-alone capability, there may be merit inconsidering this type of terminal whichhas its own independent memory store,so that increase in demand for termin-als simply increases the number ofworkstations without necessarily re-quiring any expansion of central com-puter memory.

Finally, if the selection process getsbogged down with conflicting technicaland financial information, a useful wayforward is to simply buy a single stand-alone workstation and use it to assessboth the staff response and the productneed, prior to making the purchase ofthe large system. The current price of astand-alone system is little more thanthe equivalent of a year's salary for anengineer, and is a sound preliminary in-vestment as long as it is based on agood reliable machine, because, even ifnever used again for CAD, it can revertto use as an ordinary computer! (Thetotal capital cost per terminal of anyprofessional CAD system rangesbetween £15 000 and £25 000 whethercalculated for a stand-alone or main-frame based system.)

Computer-Aided Engineering Journal December 1984 231

Training

The training needs for staff intending tomake effective use of CAD can bebroadly grouped into three areas:

• awareness — introductory seminars,literature, exhibitions etc.• off-the-job — using software andhardware at, typically, the supplier'spremises• on-the-job — using the system inan industrial environment.

AwarenessAwareness is likely to begin after a

decision to consider investment in CADhas been made but before a particularproduct has been selected. The naturalcourse of action to follow is for techni-cal managers to start becoming in-formed on a more or less personalbasis, often from a starting point ofcomplete ignorance. At this stage it isimportant for both the design engineerbelow and the technical directorateabove to become closely involved aswell, simply because, although a mana-ger may have responsibility for thedesign activity, he may be neitheractually doing the work of design, normay he have any direct control overthe funds required to buy theequipment. There is obviously no hardand fast rule over the length of time forthe awareness phase, but it is unlikelythat a balanced broad understanding ofCAD, its types and its applicationscould be obtained in less than ten daysspread over three months. This period isimportant: it is essential that structuredand planned learning (i.e. from lecturesand conferences) occurs over a periodand is intermixed with normal work andpersonal investigations through journalsand demonstrations.

An intensive study period as the onlyelement in the awareness process canpresent a lopsided and narrow view ofthe scope of CAD. No one organisation,institution or supplier is likely to be ableto offer introductory programmes,based on direct experience, for morethan one or two types of CAD at anytime, simply because of the very highcapital cost of the equipment and thenatural limitations to personal dis-cussion presented by large gatherings atconferences and exhibitions.

At the end of this first phase the po-tential user should feel confident to dis-cuss, at a general level, what CAD is,and what it can be used for. If there is adirect managerial involvement at thisstage then awareness of system costsand possible effects on profitability willalso be important.

Finally, one or two points about com-puter technology in general merit con-

sideration. It was once essential forpotential users to be 'computer literate'before embarking upon such a courseof learning. This is, fortunately, no morethe case, and, apart from picking upjargon language on the way and strug-gling with some of the less logicalaspects of computer keyboards, thenovice will find few drawbacks to igno-rance. On the contrary, lack of com-puter knowledge often prevents timebeing wasted comparing only the ele-gance (or otherwise) of competing sys-tems' designs, and permits clear mindedconcentration on the more importantsubject of how well they do the jobrequired.

Off-the-jobIt will take many years before all

CAD systems have common operatingmethods (if ever!) and therefore off-the-job training will necessarily occur afteran order has been placed, and the usercan become familiar with the specifictype of equipment purchased undercontrolled conditions at the supplier'spremises. The length of this periodvaries between suppliers and systems,but a reasonable 'norm' is about threedays and as many staff as possibleshould take this course. There are twomain reasons for putting several peoplethrough this training: one is to spreadthe skill as widely as possible amongengineering staff, and the other is toaccelerate the learning curve of individ-uals by letting them interact with theircolleagues on and off workstation(s). Acomfortable number at each trainingstation is two, but three can also workwell as long as one of this group is al-ready fairly competent. For a variety ofreasons, this off-the-job training is oftenskimped, and this has a detrimentallong-term effect on the operation ofCAD. Much of the detailed understand-ing of the software management isgained at this stage, and, if it is missedout, bad practices can result, and tech-niques for efficient drawing, design andfile management will only then belearnt afterwards by trial, error or acci-dent. It is wise to be insistent both withdesign staff and the equipment supplierthat off-the-job training is done prop-erly at the start. It is true to say thatsome elements of CAD systems canonly be really understood after theyhave been tried in the design en-vironment, but this should be 'add-on'training rather than an excuse for de-laying an introductory course.

A turnkey CAD system lends itselfwell to the concept of off-the-job train-ing because the supplier can providetraining equipment which is nearlyidentical to that ordered. The samecannot always be said for systems

which involve different suppliers forsoftware, hardware and peripherals. Itcannot be emphasised too strongly thattraining should be done on equipmentthat is as near as possible the same asthat which will eventually be installed atthe place of work. A surprising amountof time can be wasted fiddling aroundtrying, for instance, to 'log-on' a soft-ware package which is slightly differentto that used for training, or trying to runa different version of an intelligent plot-ter. Not least of all are the problems,particularly those of response time,associated with trying to run severalworkstations from one modest com-puter when all the training was done onan enormous mainframe system.

On-the-jobThe first caution here is to make sure

that the equipment is working to satis-faction before trainees are let loose onit. There is nothing more calculated tocause disenchantment and unfair com-parisons with traditional design me-thods than to attempt a trainingprogramme on unreliable equipment.Teething troubles are inevitable, how-ever, and a careful balance must besought between what is reasonable toexpect and what constitutes cause forsuspension of training schedules. It isworth noting that as there is a troubleshooter inside every engineer tryingdesperately to get out it is inevitablethat operators will become 'fixers' aswell. Rules cannot be laid down here,but breakdowns of a new system arethe responsibility of the supplier and anearly precedent should be set on ser-vice callouts.

For initial training, audio tapes are anasset, and if they are not available fromthe supplier it is not too onerous a taskto create them in-house. If this is done,try to make them conversational ratherthan a set of clipped instructions, andmake sure that they lead the operatorthrough to a clear objective, i.e. asimple layout or drawing. A useful tech-nique with a tape programme is togradually 'forget' to give mundane oper-ating commands so that the traineebegins unconsciously to 'fly solo'.

Many operation manuals are poorlystructured, and experience has shownthat the fastest training can be done bygetting the user to create steadily morecomplex components and assemblieson the screen rather than by treatingeach element of graphics as a separatemodule. Once the operator can accu-rately reproduce a given set of drawingswhich represent, say, a recognised pro-duct in the company range, then tasksshould be set which allow an elementof design freedom to emerge so thatthe full potential of the system as a

232 Computer-Aided Engineering Journal December 1984

design tool is developed.There is some debate among users as

to whether engineers should go onto aworkstation only after they havesketched and planned out their ideason paper, or whether all work, including'rough sketching', should be donedirectly on CAD. Although the latterhas attractions, users do seem to find iteasier to 'get going' if they have donesome rough work on paper first, andthis obviously saves precious terminaltime. (A proliferation of cheap 'user-friendly' systems may, however, even-tually lead to the paperless designoffice.) Ultimately the training will coverfile management, interaction with othersoftware and hardware, and, if only atan awareness level, the potential of thesystem to operate in conjunction withmanufacture and test facilities.

The on-the-job training is of coursenever completely finished becausetechnique grows from experience andthere are always updates of softwareand hardware going on. However, muchof the basic skills for running a modernCAD system should be gained within afew months of fairly continuous expo-sure. The importance of hard copy tothe trainee should not be forgotten. Theuse of plotters should be encouraged,as the production of a drawing onpaper, no matter how simple, has aconsiderable psychological effect. As ageneral word of caution about screenand keyboard work in general, it isworth bearing in mind that, although awell designed, well lit, well placed work-station will not of itself harm the oper-ator, continuous operation over severalhours can cause considerable fatigue. Itis therefore wise at the training stage toteach users to vary their working daybetween the terminal and other jobs.

Despite the attractions of CAD sys-tems which include for instance, three-dimensional modelling and finite-element packages, basic training shouldalways be done on two-dimensionalsoftware first. This gives an earlygrounding in the handling of computergraphics and serves to discipline usersto make effective use of their time. Atthe moment, professional two-dimensional drawing on CAD shouldcomply generally with BS 308, but sincethis standard is for manual drafting, cer-tain aspects — line thicknesses, for ex-ample — may no longer be relevantand it would be counterproductive toinsist that trainees always adhere rigor-ously to this standard.

Support and management

All computer systems require bothinternal and external support. For a

series of stand-alone workstations theinternal support may need only be amember of staff being available to helpsort out enquiries and solve minorproblems, in addition to access to con-sumables, for example discs, pens,paper etc. For a large minicomputer ormainframe system this support is likelyto require full-time staff control, and itis unlikely that this can always be donewith existing drawing office staff. Areview of the management of large sys-tems has shown that a special type ofperson is emerging to handle this newtechnology who has both design officeand computing experience and is cap-able of dealing with both the day-to-day running and the changes insoftware and hardware that occur asthe system develops [9].

Security

Some of the very things which makeCAD an attractive proposition to manu-facturing companies — such as fastaccess to drawings and parts lists, easeof drawing modification and ease ofaccess to databases — also present asecurity weakness. Many of the systemsdescribed are more reliable if left onpermanently, and therefore there isnothing to stop unauthorised use. Themost simple first level of security is aunique user operating code number,but care must be taken, particularlywhere group work is being done, thatthe number does not slide intocommon use. Where work is stored ondisc or tape it is usually very simple toduplicate and note, for example, that a3 in floppy disc can carry a completeset of detail and assembly drawings and

can be concealed in a wallet [10]!Another aspect of security is protec-

tion of hardware and software from ac-cidental damage or abuse. The systemshould be robust enough to survive or-dinary wear and tear, but recent experi-ence has shown that electric storms, forinstance, can overload computers andwipe out work in progress. A good soft-ware system should therefore haveboth buffer stores to save work as it isbeing done and a visual reminder on,say, a 20 minute time base, to ensurethat design work is always secure.

Future development

There is no doubt that the current trendtowards lower-cost higher-power com-puters will continue and that there willbe a parallel improvement in both theperformance and ergonomics of CADequipment. This is already leading tothe concept of the 'engineer's work-station', which has both its own com-puter power and direct access to othercomputers, both inside and outside theorganisation.

Software systems will become moreengineering orientated and will be ableto offer databases of standard parts aswell as analysis packages, and there willbe a growth in programs with which theengineer can interact to build up spe-cific product data.

All this inevitably means the end oftraditional design/drawing offices and amuch closer link between design,manufacture and test facilities. It is un-likely, however, to herald the end of theengineering drawing as the primemethod of conveying design informa-tion: it will just revolutionise the way itis done.

References

1 PARTRIDGE, J.: 'CAE systems — the integration of design and manufacture?', Computer-Aided Engineering journal, 1984, 1, (5), pp. 155-158

2 'Start small (CAD at Southampton University)', CADCAM International, 1984, 3, April3 'Making a start in CAD', Engineering Materials & Design, 1984, (3) and (4)4 CUDE, J.: 'Recent advances in computer graphics in the shipyard industry'. Proceedings

of IMechE Conference on Effective CADCAM, Cambridge, England, 29th-30th June 19835 COX, J.: 'Formula one shapes up'. Proceedings of IMechE Conference on Effective

CADCAM, Cambridge, England, 29th-30th June 19836 BRUNDLE, K. S.: 'Computer aided engineering at Short Brothers Limited'. Proceedings of

IMechE Conference on Effective CADCAM, Cambridge, England, 29th-30th June 19837 RICHARDSON, F. J.: 'Computer-aided engineering in design'. Proceedings of IMechE

Conference on Education and Training of Engineering Designers, University of Bath,Bath, England, 12th-14th Sept. 1983

8 PENNY, J.: 'Micros in engineering', CADCAM International, 1982, 1, Sept.9 'Making a start in CAD', Engineering Materials & Design, 1982, (5)

10 'Security and desktop computers', Engineering, 1984, Jan.

P. E. R. Mucci is with the Department of Mechanical Engineering, University of Southampton,Highfield, Southampton SO9 5NH, England

Computer-Aided Engineering Journal December 1984 233