Computer-aided mechanical engineering: 1958 to 1988

Computer-aided mechanical engineeri ng: 1958 to 1988 W S Elliott

A review of the development of CAD, seen from a mechanical engineeringandUKperspective, is presented, Thirty years of work on various aspects of CAD are discussed and the origins of some commercial packages such as CAM-X, Cadds-4X and Duct described, mechanicalCAE, CADCAM history

Tracing the beginning of a subject is like tracing the source of a river - the Thames or the Danube say. But the Danube has its place that is pointed to as its start -Donaueschingen- and CAD does too. Mechanical engineering has the distinction of being the discipline which fathered the birth of CAD, 30 years ago. MIT provided the fertile ground. In the early 1950s the Computer Applications Group of the Electronic Systems Laboratory (formerly the Servomechanisms Laboratory) pioneered paper tape control of machine tools leading in the later 1950s to the development at ITRI of the APT language for automatic programming of tool movements, In 19581 Dwight Baumann and Steven Anson Coons of MIT Mechanical Engineering approached Douglas Ross of MIT Computer Applications Group, 'to see whether it might be possible to take another important step beyond APT'. Then want to use the computer 'in a much more direct and powerful way in the chain of events that begins with the original concept as envisaged by the designer and culminates in the production of the finished device', words which were far-seeing. 2 At that 1958 meeting a system was outlined that would bind man and machine 'in an intimate co-operative complex, a combination that would use the creative and imaginative powers of the man and the analytical and computational powers of the machine each with the greatest possible economy and efficiency'. They envisaged the designer inputting at the screen, calling for structural analysis, for tests of clearance between adjacent parts or for calculations to optimise the design. The outcome of this meeting was a formal arrangement for Computer Applications and Mechanical Engineering to work together in a broad study of what they then named Computer-Aided Design. Funding •Department of Computing and Control, Imperial Collegeof Science and Technology, 180 Queens Gate, London SW7 8BP,UK

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came from the US Air Force Group which had supported first Numerical Control and then APT. CAD had been born by Mechanical Engineering out of Computer Applications. In this paper we look now at the nurturing of the child over the following three decades, and at how near its practical achievements have come to the broad aims of Baumann-Coons-Ross. The history of curve and surface design, an essential in much mechanical engineering CADCAM, is traced by Farin 3 in this issue.

FIRST SHOWPIECES In 1962, four years on from the Baumann-Ross meeting, Ivan Sutherland's thesis on the uses of a display for design, with constraints, became well known. His 'Sketchpad' paper, with one by T E Johnson on a 3D version; the prescient paper 'An outline of the requirements for a computer-aided design system' by S A Coons and 'Theoretical foundation for a computeraided design system' by D T Ross, created great interest at the 1963 Fall Joint Computer Conference (JCC). Examples in these papers were mainly of applications to structures and mechanisms. A group of five papers on DAC-1 (Design Augmented by Computer), a car panel design system developed by General Motors, with IBM, were presented at the 1964 Spring JCC. These papers, particularly Sketchpad, were seminal. In 1964 too, the important contribution by Coons appeared, on a method for computer design of curved surfaces 4. Sketchpad attracted many visitors, who returned to their bases to write Grant applications. Funds were sought, and in general obtained, 'to apply Sketchpad' to this and that problem, from the 'fairing' of ship's lines (smoothing a hull shape) to the design of shoe lasts. This was a euphoric time, it was felt that Sketchpad was a panacea for all problems and that it would produce instant results. Realisation came slowly, over the following few years, that a great deal of basic software effort was necessary for particular applications and particular computer systems. Two moves to tackle this work were made at Cambridge University and at Imperial College. While visiting MIT, Professor Maurice Wilkes recruited Charles Lang, a computer scientist and mechanical engineer, to return to the UK, with SRC support, and join him at the Cambridge University Computer Laboratory. The late Professor Stanley Gill obtained joint SRC and Mintech support to build a CAD team at Imperial College to research the 'Computer processing of 3D shapes' and 'the application of Sketchpad to ship design'.

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COMMITTEES: 1963-1969 From 1963 to 1969 four Committees deliberated and reported; each one (after the first), citing in its 'terms of reference', the conclusions of the previous one.

Feilden Report The Feilden Report was published in 1963s; its recommendations included that 'there should be a single universal language for the description of mechanical engineering parts and operations on them'. It was recommended that DSIR should support research into improved methods of producing engineering designs and that the Institution of Mechanical Engineers should initiate discussion and stimulate the adoption of the 'universal computer language for use in mechanical engineering'.

NEL Subcommittee and Rembrandt Hotel. Meeting The main result of the Feilden Report was the immediate appointment, in December 1963, at the National Engineering Laboratory (NEL), of a Subcommittee to report on: • the need for automatic drafting and machine tool control • the need for a national programming system for numerical control • the impact of computers on design and tool control, The draft report of the Subcommittee 6 recommended the formation of a National Design Service (NDS) as a public organisation, with papers in support by Charles Lang, of the Cambridge University Mathematical Laboratory, by Dr Robert Hurst, Director of Research of the British Ship Research Association and by D T N Williamson. This report was presented by the NEL Director, David Penney, to a group of senior management from some 40 firms, at the Rembrandt Hotel, London, on 7th December 19657. The report reviewed the whole design and drafting process and affirmed that Sketchpad was a most significant development and should be urgently investigated in the UK. The principal recommendation was: 'A National Computer-Aided Design Service should be set

up by government in partnershipwith industry to stimulate the adoption of the sharing of programs for engineering design.The Serviceshouldbea publicorganisationsponsored by the Ministry of Technology. The Service would be equipped with a very large multiple-access computer and subscribers would have access through data-transmission systems... The service would be located in a pleasant academic centre in contact with industrial organisations... Cambridge seems to be suitable.' Charles Lang reported on a tour of US industry on behalf of the SRC, following his two years' work on CAD at MIT under Douglas Ross, from 1963 to 1965. Lang spoke of the difficulty, in most US firms, that computer experts met in convincing senior management of the power and value of the advanced

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techniques becoming available. General Motors and Lockheed Georgia were exceptions; General Motors having demonstrated DAC-1 and Lockheed Georgia having ordered displays for part-programming of 2D parts on a production basis. 'General Motors hoped to reduce the lead time for a new car from three years to one year'. D T N Williamson presented his report, which he had circulated privately in February 1965 ~, describing, with examples, how a National Design Service would operate. A very large computer'situated in a convenient part of the country' would have 200-300 users connected by telephone lines. There would be a cooperative project with MIT and the Service would rent a large time-shared computer from the USA. Williamson listed 14 engineering problems suitable for CAD. The Williamson proposal had inspired the NEL Subcommittee recommendation and is seen with hindsight as pointing to the CAD Centre announced 18 months later (but Williamson had proposed using a rented US computer, until t h e British computer industry developed a multiple-access computer suited to the purpose). There was in Williamsons' ideas, and in other writings at the time, the concept that through their programs in the system, the 5% of designers who are brilliant, would be making their knowledge and experience available to the 95% who are less brilliant. (But this is not what happened - at least until the current progress being made with 'knowledge-based' systems - see later). In the following discussion some of the points made by industry leaders were: • a new breed of people were going to be wanted in drawing and planning offices (and it would take time to get them) • large sums of money for very large computers was not a priority (when there was too little money to train engineers in the use of computers) • the main benefit sought was the rapid transfer of design ideas into hardware; computers had a part to play, not just in design, but right through to the finished product. (B Z de Ferranti)

Maddock Working Party Following rapidly from the December 1965 Rembrandt Hotel meeting, 'because of the urgency of the problem' the Ministry of Technology set up a Working Party 'to review the report of the NEL Subcommittee, the discussions at the Rembrandt Hotel and proposals by UKAEA and Cambridge University' and to report on 'what actions the Ministry of Technology might take to speed the introduction of CAD'. (The NEL Subcommittee had addressed mechanical engineering but the Working Party had a wider remit). The Working Party was chaired by luean Maddock, then a Deputy Controller at Mintech, with Mintech and UKAEA members, two members from Universities and three from industry. Two of the three industry members were practising mechanical engineers: J F Wallace and D T N Williamson. The Party cited the expected advantages of CAD, including improved design, much

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shorter lead-times and follow-through to machining. (It is seen today that the first and the last of these advantages have been achieved, but not 'much shorter lead-times' in all applications), After meeting weekly for two months in early 1966 with 'vigorous participation by all members' the Party extolled the British computer industry to exert itself, announced the imperative of a UK national multiaccess experiment (using an imported US multiple access computer) and of a coordinated programme of CAD work at NEL, UKAEA, Cambridge University and Imperial College. To help achieve these aims, an ICL Atlas II computer, then in 'mothballs' at West Gorton was to be installed at Cambridge University, having a specification similar to the one at UKAEA. A Management Committee was to coordinate the activities at the four centres. There was to be a National ComputerAided Design Demonstration and Experimental Centre (the NDS of the NEL Subcommittee Report) for which 'a large US computer with multiple-access consoles, computer graphics and appropriate software' would be imported. This £10 million programme was to be spread over five years and was to make CAD 'self-propelling' by the end of that time (i.e. in 1971). These recommendations seem to have been filed and no more was heard of the Management Committee to coordinate the CAD work at four centres. What did result was very different from the recommendations: • the setting up of the CAD Centre (announced July 1967) • the CAD Advisory Committee (inaugural meeting 14th July 1967) Thus the two recommendations of Maddock 9 (to put the Atlas II at Cambridge University and to import a large US multi-access computer for a National CAD Service) had been rolled into one very different animal, by a process which itself makes a separate and interesting history,

Penny Advisory Committee The CAD Advisory Committee was set up 'to assist in the development of the co-ordination of CAD work in Ministry establishments, industry and the Universities'. 1° The Chairman was F D Penny, Director of NEL, and the Committee had 37 members. Seven Subcommittees and Working Parties were appointed. The First and Second Annual Reports present a wide range of recommendations on ways of transferring technology and 'making things happen'. The Reports were source material at the time on ongoing projects and the meetings brought together everybody concerned with CAD. The main contribution made by the Committee was in 'everybody telling everybody else' what was happening and in the mild 'pressure group' activity, This extended to getting the CAD Centre going and appointing a Director. No record is available as to why the Chairman, in November 1968, a few days after taking up his new appointment as Director of Y-ARD, Ltd. received an unexpected letter from Tony Benn, the

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then Minister of Technology, disbanding the Committee. This letter was read to the Committee at its meeting on 6th November 1968,11was received by the members with considerable surprise, and that was that.

CAD CENTRE The Maddock Committee had recommended in its Report of June 1966, that the National Computer-Aided Design Demonstration and Experimental Centre, should be based on a large multi-access computer to be imported from the USA. A separate recommendation was that the Atlas II computer, which ICL had 'in mothballs' should be installed at Cambridge University. The decision of the Technology Minister to site the Atlas II at a Ministry-supported site at Cambridge rather than at the University was announced in July 1967. The Penny Committee recommended in 1968 that the setting up and running of the Centre should be contracted to ICL and the Director should be appointed by ICL. During 1968 a management contract was placed with ICL and the Centre opened with 20 staff in March 1969. The Director, Arthur Llewelyn, was appointed from Mintech headquarters staff. Brian Gott, an aeronautical engineer, arrived on 1st April 1969 to be responsible for the Application Groups with David Stevens joining soon after to head the Mechanical Engineering Group. In Mechanical Engineering, the Centre was known for two products, Graphical Numerical Control (GNC) and POLYSURF, one of a number of packages which were available for free-form surface design. An engineer, K J Davies, joining from the AE Group had been looking for an NC programming system that was easier to use than APT; he had views on how to use interactive graphics as input. The Group drew up a specification, which was taken for comment to Hawker-Siddely Aircraft, to a tool and die company, and to others. In the Centre, Richard Newell provided a command structure and other tools a n d GNC (Graphical NC) evolved, as a system to drive Ferranti Profiledata; Profiledata drove the machine tool through a post-processor. The Centre had to a degree been a political football throughout its life and particularly in its gestation period. GNC is a small example. In the course of its development, a typical divergence of view arose, which well illustrates the delicate politico-technical balance which the Centre had to ride through. There were many NC languages from which one could be chosen for GNC (APT, 2C, L, Profiledata, EXAPT being a few). Malcolm Sabin of BAC having authored NMG (Numerical Master Geometry)visited the Centre to advise on the use of Profiledata. BAC exchanged rights to use a version of Profiledata for computer time 12. ICL had chosen 2C, L, a 'British version' of APT from NEL. As the Centre was in effect part of ICL, the choice of Profiledata, made on entirely technical grounds, became a political difficulty for the Centre, which was criticized for persisting with GNC 13. A more fundamental difference in Centre policy became apparent. To simplify, one view was that the Centre should produce software tools and should

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develop technologies, from which applications could be produced by industry; the other that application packages should be written and supported by the Centre, using tools sourced no matter whether internally or externally to the Centre~L According to some who were Centre staff at the time, this mid-1970s conflict of strategy fuelted a feeling that, at least in mechanical engineering, the Centre had lost keenness to know where it was going. Regarding the CAD Centre, the final report to MEMTRB of Williamson's CAD Steering Group was, after much discussion in Committee, laconic in the extreme: 'We make no recommendation regarding the future of the CAD Centre'. A paper by Williamson TM, not generally circulated, stated that the Centre's ME Group needed strengthening and proceeded to comment, with true Williamson acidity, on a proposal to solve the vexed problem of the Centre's future by moving it and twinning it with the coming SRC Interactive Computing Centre at Chilton: 'This would be mating two dodos. This bird will not fly.' After such trenchant criticism the Centre organised a day's conference at the Kensington Hilton to present its current work and future plans to the DTI Chief Scientist, luean Maddock, members of the MEMTRB Steering Group and other influential people, The presentation did a great deal to raise the stock of the CAD Centre; but the proposal to merge with Chilton and the known criticism precipitated many resignations of key senior staff. Staff who resigned set up their own companies, some of which have flourished. After a relatively short time the Centre, privatised, became CAD Centre Ltd with a Manufacturing Industries Division that successfully sells and supports GNC (which now includes Polysurf). GNC is a de facto international standard for part programming and is the NC part of design packages from IBM, Ferranti, Computervision and other major vendors, MI=I~I1.FU3 The early 1970s saw progress on a broad front in CAD research and application, in universities and industry, But following a change of the UK Government, and the consequent shutdown of Mintech and a rethink in the new Department of Trade and Industry, on how Government should fund technical development in industry, the 'Customer-Contractor' concept was adopted, with Requirements Boards for each sector. But while this rethink was going on, although CAD research and development continued on a fairly broad front, working out the initiatives taken in the late 1960s, there was littte encouragement or further support from Government. SRC support for University projects was drastically cut and with notable exceptions, support for CAD developments in user industry was slowed down. An area of marked progress was in the vendor industry which became active in developing and offering 'turnkey' hardware/software systems for 2D drawing, some with limited 3D capability, Among the turnkey vendors Computervision was the most successful but Unigraphics was installed in, or being chosen by companies such as Baker Perkins,

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W S Atkins and Unilever. A 3D design package, 'AD 2000', developed by Manufacturing and Consulting ServicesInc. (MCS) had been specified by Los Alamos; U K A E Aintroduced Patrick Hanratty, the proprietor of MCS, and AD 2000, to the UK, where it received much attention. Licences, said to be 'exclusive', were taken by a number of vendors, and Computervision's CADDS 4X derives from it. In terms of industry take-up however, by 1975 there was a groundswell of opinion that 'something should be done about CAD', and the Mechanical Engineering and Machine Tools Requirements Board set up a CAD Steering Group to tell it what to do. The task of the Group was stated as: 'to encouragethe spread of CAD in mechanical engineering industry by initiating and co-ordinating work on CAD programs.., and in certain casesto provide the foundation for work as well as provide advice...' Williamson, who had moved on from Molins to Rank Xerox,an MEMTRB member, was asked to form and Chair the Steering Group, which met between 15th April 1975 and 31st March 1978. The Steering Group was convinced that 'the use of CAD techniques for design is only the tip of the iceberg and.., the real pay-off will be when data capture.., is applied for the benefit of the totality of an engineering business', and accordingly one of their top priorities was integration. A new facet of integration was to use the upstream design input to provide information downstream not only for production but for other aspects of the business such as estimates, planning, shop routing and purchasing. In this connection J F Wallace put forward the concept of a 'Linked Engineering Business System '~, referred to in the later ACARD Report on CADCAM ~. A main priority was to assist a number of firms to install, evaluate and report on the advantages and disadvantages of using available (US-sourced) packaged computer-aided drafting systems. Support was given to Ford, Vickers and GEC, all in partnership with the CAD Centre, to install systems. (At Ford, visited in 1988, great progress in CAD has certainly been made, though the MEMTRB help is only dimly recalled). Encouragement and direct advice was given to Ferranti to produce a turnkey system based on its own user requirements and this lead has resulted in the Ferranti Infographics CAM-X product, selling well today into Europe as well as the UK. Techniques and systems were reviewed by specialist Groups in Surface Design, Structures and Mechanisms. Nine surface design packages were reviewed including Potysurfand Duct. The Surface Design Group commented that the only systems available commercially were Polysurf, APT/Fmill and APT Sculptured Surfaces. BAC APT/NMG was shortly to be marketed. Polysurf needed modifications to overcome rippling under certain conditions and could then be marketed by an agent external to the CAD Centre. The Group questioned however whether further work should be done on Polysurf because it was based on Coon's patches, not B-splines. In the Structures Group a need was stated for an interactive program to enable a

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designer to make rapid interactive modification to a first guess and to 'home' in on an acceptable design, Its Final Report left the Group discussing ways to realise this aim. A great deal of work was done in Mechanisms and several proposals for funding were made, and accepted by the Board. Much attention was given to volume and surface modelling. Existing descriptions were based on APT, a series of unbounded surfaces containing the part. Designers and engineers, it was said, did not readily visualise in this way. Visualisation in general engineering was achieved more naturally by combining simple shapes. The PhD thesis of 1 C Braid 17, offered this alternative geometrical concept and the Group felt that this work should be encouraged. Accordingly, John Wallace, for the Steering Group, negotiated with SRC and with Maurice Wilkes, Director of the Cambridge University Mathematical Laboratory, for continued support for Braid's work. At the same time alternative commercially available turnkey systems, Computervision, Applicon, Lockheed Cadam and Hanratty's AD2000 were to be reviewed, partly by the programme of 'hands-on' experience at Ford, Vickers, GEC and elsewhere, The Steering Group felt that the time has passed when it would have been helpful to set up a large central specialist group for CAD in mechanical engineering, to act as a 'broker' or as a 'centre of excellence'. It did not support the idea of the ME Group at the CAD Centre filling this role; they should transfer their expertise to industry thr0ugh partnerships, instead of continuing as 'the fount of all CAD knowledge'. This attitude, perceived as being held by the Centre, was considered by the Steering Group to be a hindrance to the spread of programs on their merits. Wallace assisted Williamson with the Final Report of the Steering Group in 1978. Then, Williamson, 27 years after his initiative with Charles Allen in NC (see next section) fulfilled his wish to live in Italy and influenced the scene no longer, The Steering Group had been responsible for a number of initiatives, in the form of funded evaluation programmes in industry, such as the one at Ford, where the results after due time could be seen by others. FollowingtheMEMTRBGroup's1978Report, ACARD in January 1979 set up a Working Group on CADCAM, chaired by Sir Robert Clayton and including Sir leuan Maddock. The main recommendation of the Group 16 was that DTI should mount an 'Awareness Programme' in CADCAM. Thus the sequel, in the 1980s, to the MEMTRB evaluation projects in selected firms, was to use these projects and a wider selection of other companies, to show the benefits of CADCAM more widely,

I N T E G R A T I O N : F R O M C O N C E P T TO PRODUCT Coons foresaw that the functions of analysis, numerical control and the rest would take place downstream from the geometry and attributes that had been input by the designer. B Z de Ferranti had underlined the

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importance of the point at the 1965 Rembrandt Hotel meeting. In mechanical engineering, the advantages of compurer aid at all the stages of production of artefact and documents are so great, that to derive most benefit we have to look at computer integrated manufacturing; applying the computer not only in the drawing office, but also in part-programming, process planning, machine loading and machine supervision. To use the computer only for design is to deal with only 5% of the problem. We illustrate by the successful pursuit of integration in the Ferranti Scottish factories. Charles Allen joined Ferranti at Crewe Toll, Edinburgh, as a draftsman in 1943. In 1951 as Chief Draftsman he was producing drawings for a radar block, an item that was extremely difficult to manufacture. In pursuit of improvement, the application engineer, Williamson, and Allen went to the International Machine Tool Exhibition in Paris to select machine tools likely to be adaptable to numerical control. Williamson returned to design the control systems and Allen to 35 years of dedication to computer-aided design, drawing and production. To record events in the computerization of the Ferranti Crewe Toll drawing office and workshops is to write a history of CADCAM engineering of small batch precision items. In 1953, a Mark 3 HC system had been shown at the Machine Tool exhibition in London; in 1955 it was at work for the Radar Department at Crewe Toll, helping to make the RF block. There were considerable difficulties. The tools were unreliable. Sending paper tape to a distant bureau computer, to receive back a mega-length magnetic director tape (the coded instructions to the tool) was almost unworkable. Williamson had moved on to the Molins Machine Tool Company, and his successor at Ferranti, H. Hinkley, with his Chief Engineer and Allen, visited ITRI to see APT. They did not like the enormous processor needed to compute APT statements and they returned to specify and develop an alternative and, to them, more acceptable part programming language, Profiledata. Adaptability of Profiledata to other situations is exemplified by its adoption by H P Y Hitch for aircraft skins and frames at BAC, Weybridge, UK. A Ferranti Board decision in 1968 had a most far-reaching effect. Allen was asked to take over Production at Crewe Toll, while retaining the DO. This enabled Allen to plan and supervise 20 years of managed change. From 1970 to 1980 Ferranti made a massive investment, with little to show externally, but in work crucially relevant to the next leap forward in the 1980s. The investment was in standardisation of materials, tools, and fixtures. At the beginning of this period, on average, a director tape needed six attempts before becoming error free. When Computer Numerical Control (CNC) was introduced in 1977, and some errors could be edited at the machine, the number of attempts at an error free tape dropped to an average of three. There was then pressure to get tape entirely 'right first time'. Error was reduced from 20% in the early 1970s to 1% in 1988. The battle for 'right first time' has been won by the standardisation work of the 1970s, by vastly improved machine tools and CNC, and by

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rapid evolution of the computer systems used in design and part-programming, F r e e d r a l t to C A M - X Meanwhile the Ferranti Information Group (lEG/ was formed after the Ferranti NC business had been sold to Plessey, following BAC Filton's switch from Profiledata to APT. lEG obtained Mintech support for computeraided drawing office systems, culminating in Freedraft. A proposed cooperative between Ferranti, ICL and BAC to produce a Drawing Office Automation System (DOAS) defined by BAC as customer, to be DTI supported, fell apart. DOAS was not begun because, it is said, all DTI finance for computing was needed at that time for an tCL survival package. Following the DOAS failure Ferranti now had a workstation running from a 16-bit machine, Argus 700. lEG had to drop th!s because the only software support for the Argus was in CORAL, (Common Radar-oriented Assembly Language), a fine language for radar simulation but not for drawing office automation, Nor did Freedraft on DEC's PDP-11 offer a starting point for new products because in the mid-1970s there was no operating system, for the PDP11 with multitasking, to allow 'multi-seat' working. Pressure from the DTI, spearheaded by Wallace, on behalf of DTI and SRC and with financial help from both, encouraged Ferranti (who had now merged their lEG with CETECto form Ferranti - CETEC, (later renamed Ferranti-lnfographics) to take a fresh start and consider an interconnection of packages. The core was an exchange (the 'X' in CAM-X) or supervisor, and interfaced to it were a number of packages. These came from a variety of sources (see Table 1). In urging Ferranti to follow this route, Wallace asked that Ferranti Defence Systems, Crewe Toll should join, as a user organisation, with Ferranti Infographics, in evolving the product specification. The result was CAM-X, a modular product, which permits change of the constituent modules as technology advances. The modules which were in the initial version have now been largely rewritten or replaced and a major upgrade that allows the user greater ease of input, was shown at the CADCAM Exhibition in March 1988. Today at Ferranti Defence Systems, Edinburgh, CAM-X workstations linked to a VAX 785 are used by draftsmen, with 2D drawing and 3D modelling modules, to create the drawings for components, but GNC is not used. Instead, the part-programmers have simpler workstations, online to the same VAX through which they have access to the geometry of the components, Table 1, Packages and sources of CAM-X

Purpose

Package Source

2D drawing Freedraft 3D modelling Romulus Parts-programming GNC Finite element analyses Femgen Management of engineering records ERMS

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Ferranti Shape Data CAD Centre FEGS,Cambridge ARC, Cambridge

l-hey transfer this data at will to produce machining tapes by means of an inhouse program, Simplified Cutting Sequence (SCS). Machining technology is added automatically and the machining cycle can be simulated on the workstation for tape proving. Another inhouse program is used for production planning. The 1988 release of CAM-X is now being integrated into the Defence Systems Information net, and the system is producing assembly drawings for handbooks. On a central company ME29 system, a listing of all components whether produced inhouse or bought out is carried, with parts numbers and drawing numbers. More production planning and shop loading is done in a distributed computer system but keeping firmly to the principle of an integrated database; every item is recorded and updated in only one place. The Ferranti Scotland system has now reached a high level of integrated CADCAM, carrying out operations on information originally input upstream by designers, part programmers and process planners, as foreseen at different times by Coons, by Penny, by Williamson and by Wallace, and as worked for steadfastly by Allen since 1951. Similar progress by a small number of other firms is recorded in the Proceedings of the November 1987 IMechE Conference on Effective CADCAM ~. U S E OF M O D E / / E R S

A N D TLIRNKEY

DESIGN SYSTEMS Visualisation

and Realism

The early 'showpieces' constructed and displayed 3D shapes by lines and points. Cartesian coordinates of each point were input and a connectivity list recorded which point-pairs were to be connected by lines. From the computer model in 3-space, a projection onto the viewing screen was computed in the display processor. The user viewed a 2D line-point structure and, if the object was of regular or expected form, s/he could visualise the 3D shape. This representation was dubbed 'wireframe' and is still used for many purposes today. Aids to visualisation of a wireframe projection were researched in the late 1960s and early 1970s. Ortony 19 developed a stereo 3D viewer. In ICON 2°, visualisation of inherently line-point structures (ship hulls and gas platforms/ was aided by real-time rotation of the structure under joy-stick control, and by machinedriven regular oscillation of the model through a small angle. A great deal of work was done in the late 1960s and early 1970s, particularly at the University of Utah, on the realistic display of solid objects, by the removal of 'hidden' lines and surfaces and the computation of surface reflection for arbitrary viewing angle and arbitrary angle of incident light. While more and more realistic pictures were produced, Licktider 21commented that in the engineering design context more realism does not necessarily bring more insight. In the 1960s, while 3D wireframes were useful for the representation of aircraft fuselages, car panels and ship's hulls, the greater need was for a computer aid to 2D drafting, to give the draftsman working with three orthogonal 2D views, increased accuracy and greater productivity.

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Packaged or 'turnkey' drafting systems became commercially available. As product ranges developed, limited 3D facilities were added onto the 2D systems.

Designing with volumes In the early 'seventies' attention was given in several places, including Cambridge, UK and Rochester, NY, USA to constructing 3D computer models by Boolean operations, sometimes rigorous, sometimes less so, on primitive shapes; the primitives if not already stored were created by 'sweeping' or rotating a 2D structure, It was thought by some, notably Williamson, that practising engineers would prefer to create and to visualise their components by 'building' in this way. Braid joined Lang as a PhD student in Cambridge in 1969 and, with Lang, visited Williamson at Molins. Williamson encouraged the work which resulted in 'Designing with Volumes '~7 and the modelling systems Build 1 and Build 2. Parallel work was proceeding elsewhere, for example by Okino 22 and Baumgart 2~. In 1975 Braid 24 reviewed six systems for shape design and representation and solid modelling became a fast developing academic subject, Commercial realisation of solid modelling came with the formation of Shape Data Ltd by Lang, Braid, Grayer and Veenman in 1977. A new modeller, Romulus, following the Build concepts, was written, and licences were sold for its incorporation into 'turnkey' systems such as CAM-X. Another company supplying a modeller integrated into a design system, Cambridge Interactive Systems (CIS), was founded by Newell, Sancho and colleagues from the CAD Centre. Early advertising suggested that the CIS modeller used Romulus; the myth remained for some time. To improve ease of use they devised a way of annotating 2D drawings to indicate 3D relationships and so build a 3D model. The CIS Medusa workstation has a large high resolution master display and a Sun 8 Mbyte real memory processor. This is 4.5 times the processor speed of the Prime 300 used in 1980. In 1980, the display was separated from the processor by a 1200 baud line. Processor and display are now packed 'all in the one box', avoiding the 1 2 0 0 baud speed limitation.

Simulated Drawing Office Williamson's opinion that engineers would prefer to 'build' and visualise components by adding, subtracting and intersecting primitive shapes was not (and is not) shared by all practising engineers. D B Welbourn felt that for an important class of object it is more natural to sweep a variable curve along a line in 3-space, to which it is orthogonal. The product Duct is discussed below, Hitch, writing in 19762s, pointed out that after 200 years of development and use, the classical engineering drawing is remarkably efficient. Any rival scheme for inputting and viewing in 3D must be extraordinarily good to supplant it; including the details a draftsman must be given on a display, with fast response-times for checking, to simulate classical

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drawing practice. Hitch could find no effort going into this possibility in the UK, in 1976. But 'turnkey' (packaged hardware-software) design systems have steadily evolved through and since the 1970s, from the 2D drafting aids to designer workstations incorporating very advanced solid modellers. They accommodate Hitch classicists, whose physical drawing board has been replaced by a quite large flat screen with very high resolution pictures. The draftsman works as he has traditionally worked; but with powerful computer support that can provide sections, enlargements and exploded views quickly. With this support his effectiveness in working traditionally is greatly increased; and the Braid volume-building facility is available too. The user has a choice of method of entering the information to create the 3D computer model. When it has been created, required views and cross-sections can appear in the traditional 2D world. This availability, for a small percentage of tasks, of what some engineers pejoratively style 'fancy' or 'exotic' 3D facilities, within a design/manufacturing workstation (which is primarily a glass drawing board) is the realisation of what Hitch sought in 1976, and is seen in 1988 in full scale use.

Commercially available packages with

modellers BesidesCAM-X with Romulus and CIS Medusa there are many other commercial 3D modellers and other design systems on mainframe and in turnkey design stations (workstations). Cadam was written for mainframes in the 1970s by Lockheed for aircraft design and is marketed by IBM. It became the basis for the Ship Design system, Britships 2. Similarly Catia was written by the French airspace company Dassault in the early 1980s and is also marketed by IBM. Computervision Cadds 4X modelling and NC software is widely used, and is much seen in car and engine companies. Unigraphics is used at Baker Perkins. The organisation, CAM-I, conducted comparative tests of modelling using a particular piece-part, from MBB, which thus became the best known engineering component in the literature. CAM-I proposed 'standard' interfaces to modellers; Shape Data and the Cranfield Institute have both made implementations. In 1980, the practical use of modellers was not easy; taking cross-sections and different views was difficult and time-consuming. Between 1980 and 1982, Medusa, Cadds 4X and Catia became available, giving so much more speed and useability that real productivity gains in practical use started to be seen in 1984 and have continued. The change has been brought about by improvement in display technology, and by the 'VLSI effect'.

A Spine-based Modeller - DUCT Classicinteraction between industry and academia led to another route to 3D modelling. At the Ford Research Centre, in 1969, Stanley Mathews was turning over in his mind what might be the best way to model certain

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car engine components which shared a duct-like form. He conceived the idea of a description based on a line in 3-space intersected at intervals by planes orthogonal to it, the planes carrying curves which together define the surface. Welbourn of Cambridge University Engineering Department and Director of the Wolfson Cambridge Industrial Unit, a practicing engineer with great interest in shape description, had been thinking on similar lines and felt Mathews' idea to be worth investigation. Mathews came to work with Welbourn at Cambridge and a Research Assistant, 1 H Gossling, was set the task of programming and implementation, In 1973, Delta Metals seconded an engineer to the team. A system was in operation in 1974 and a paper by Gossling at the 1976 CAD/ME Conference at Politecnico, Milano, Italy '~ set out the mathematics of its implementation. At this time, the Duct system was applied to some trial products of Delta Metals and by 1977, one Swiss firm had taken a licence, and one British firm was using the system, In 1977, Deltacam was formed to exploit Duct with a staff of five, which was to grow to 95 by 1988. D P Sturge joined the team at Cambridge in 1978 and discovered that the system as then conceived and programmed had shortcomings at patch boundaries for some objects. These shortcomings derived from the method of definition given by Gossling 26, whereby continuity of first derivative across the boundaries of bicubic surface patches, was not secured. Sturge changed to a system in which spine and sections became data inputs, surfaced by patches with cubic boundaries and internally, sixth degree polynomial Coons surfaces chosen by Sturge to be smooth and fair. C 1 continuity across boundaries was afforded,

when previously there was no first derivative continuity on the surface. The Duct package today provides colour-shaded images as well as wireframe representations (see Figure 1) and NC tool paths. Its best application is to NC machining rather than to design. In fact, some users design on another system and transfer data to Duct. Transfer is made possible by the Interactive Graphics Exchange System (IGES).which includes a file of coefficients to define a surface. Colour plate 1 shows a wireframe manifold and Colour plate 2 is an example of a colour shaded image of Figure 1. In 1977, Duct was made available to small firms, typically in the jig and tool industry, who used the software by a terminal, consisting of a direct view storage tube and a plotter, connected by acoustic coupler to a bureau. In the 1980s, however, owing to the 'V[SI effect' there has been a transformation in the method of use, with the availability of lower cost but powerful 32-bit computers and the trend towards one workstation/person. CADCAM APPLICATIONS To illustrate historical developments described in the previous sections, three 'case histories' are given, of example firms, who were 'demonstrators' in the DTI Awareness project, followed by brief histories to present CADCAM in the aircraft, car and ship industries.

Piece parts and general engineering CrosfieldElectronics Crosfield Electronics makes computer-based products for the communications and printing industry. Crosfield's

Figure 1. Wireframe violin drawing produced by Deltacam using Duct

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headquarters is at Hemel Hempstead with manu o facturing and assembly in Peterborough and a CNC machine shop at Milton Keynes. A Computervision system with Cadds 3 was installed in 1978 and has been progressively upgraded. In 1983, CIS Medusa software was installed on Sun workstations linked together and to a file server by Ethernet. Medusa was chosen to replace shared-resource Cadds 3 because each workstation now operates independently with no response time problems and the 3D solid modelling package is rated as 'usable'. The capital cost of the system was paid back in two years, The production engineers at Milton Keynes work from drawings printed at Hemel Hempstead, from which they manually key data in to an Olivetti M40 running NC software - a less than ideal route to NC. It is planned to install CAD Centre's GNC, with Medusa, to prepare automatically production information to go by tape to Milton Keynes. (A data link is a budgetary problem only). IGES is used to transfer data to Applicon, which is used by a subcontractor, (}Her Conlrol$ Otter 27 designs produces and markets a range of thermostats and cut-outs and had great need to reduce product development time; designs also needed to be 'right first time'. Otter selected a system with full 3D solid modelling, to allow complete product definition at an early stage; this model could then be accessed for suitability for moulding, stress analysis and material usage. It would also allow for the design of moulds and provide NC data to machine them. Many systems were reviewed; those which only produced wireframe representations were rejected, leaving only a small number of true 3D solid modellers, from which Romulus was selected, in the Ferranti Infographics CAM-X design package 27. Otter found there was total integration of Romulus within CAM-X; commands and menus are unified between 2D design and 3D modelling, so that the designer can move freely between 2D and 3D. Experience at Otter vindicates the Williamson thesis; designers use the modeller to produce 95% of product drawings; and find no difficulty in using the modeller to express their ideas, It is satisfying to note that Otter had no background in CADCAM until they attended the 1983 IMechE 'Effective CADCAM' Conference and yet as early as 1985, they were awarded the CADCAM User of the Year Award. Baker Perkins Another winner of the CADCAM User of the Year Award was Baker Perkins, Peterborough, now APV Baker. While Otter is a small company, mass-producing a small number of designs, Baker is a large company with evolving products, produced in medium, not mass, production runs. This difference between the businesses meant that Otter wanted 3D modelling not drafting, In Baker, the major proportion of drawing office load is concerned with adaptation of existingdesignsto meet

volume 21 number 5 june 1989

the special demands of overseascustomers-whotake 80% of turnover. To Baker, 'expensive add-ons', such as the 3D used by Otter, are not essential for most engineering design and can be counterproductive. Its firm requirement is a computer-based geometry interface at all stages from the designer to the machine tool. The Baker Perkins CADCAM story has been well recorded by Systems Manager Jackson 28, who was asked by management to investigate drawing office efficiency. He visited the CAD Centre and could not see anything there that offered the productivity needed. In December 1976, with the committed aim of reducing the drafting load and thereby switching resources to more creative work, Baker set up a Working Party to investigate CADCAM. The Working Party visited several users in the USA and was also disappointed by the low productivity it saw. Vendors did not appreciate the significance of CAD as a repetitive drafting tool and of CAM for the manufacture of simple shapes. By chance, the Party visited a company in their own group which used a United Computer Corporation (UCC) p r o d u c t UNI-APT, with part-programming on a minicomputer. UCC had realised the need for a graphics front-end, at about the same time as the start of the GNC initiative at the UK CAD Centre, and in 1975 it had bought, from Pat Hanratty's MCS, the exclusive rights to 'AD2000' (as had other organisations). The resultant Unigraphics product was seen by the Baker Working Party at 3M, and a 4 terminal Unigraphics system was working at Baker's Peterborough site three months later~ A second system was installed later in 1977 and a third in 1978, with 32-bit CPUs introduced from 1982. In 1988 there were 54 workstations. The powerful 3D capabilities of Unigraphics (originally sourced by the 'exclusive' licence from Hanratty) are indeed used by Baker for complex geometry, but over 99% of CAD work is produced in 2D. Most conceptual work is however still carried out by conventional means. It is more cost-effective to employ industrial designers of higher degree standard making sketches than to use any CAD system. There are now over 50,000 CADCAM files, and steps are being taken, as at Ferranti Scotland, to link CADCAM to the mainframe for more efficient file management and online availability of drawing files. Grant aid towards the capital cost of the first system and a 5-year development grant given by the DTI were appreciated. The grant assisted the training of over 300 staff to use the equipment and brought a requirement to audit the return on investment. A productivity gain of 3:1 has been achieved on mechanical drafting. The site is important within the DTI Awareness Programme and is much visited.

Aircratl indu$1ry In the aircraft industry, more than in others, there has been collaboration between companies and there has been much grouping and regrouping. This affected early CADCAM development in the UK, while in the last

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decade the UK record is more typical of the industry worldwide, In the UK in 1946, there were 24 independent airframe companies, these were reduced until by 1969 there were just two large groups, British Aircraft Corporation (BAC) and Hawker-Siddely Aviation (HSA). Each group owned a number of widely-spread sites. There were a few largish groups, Westland, Shorts and Handley Page as well as the two majors. Development was largely left to individual sites and early use of computers was made by most sites for technical computing. Size and speed of aircraft increased apace, and by the time of the Vanguard (1958) new manufacturing methods were being introduced for the heavier skins and frames. Ferranti NC systems were installed at Vickers, Weybridge and elsewhere and part-programming commenced but without aid in calculating 'change points'. Ferranti Profiledata was then introduced, providing a geometric language input. In the U S A , parallel development occurred with the ITRI APT system. Preparation of control tapes for machines, from Profiledata output, had to be done at Ferranti Dalkeith. There were hold-ups, and BAC and HSA joined with others in clamouring for their own computers to process Profiledata output. The Ferranti response in 1965 was the product Copath which enabled customers to prepare their own control tapes. One Copath system servicing several of the original Ferranti control equipments is still in use in British Aerospace 2~. While this progress was being made in CAM, the problem of defining and machining the exterior curved shape of the aircraft was tackled. Earlier solutions had lacked generality. The use of quadratic bicubic patches (Coons' patches) was investigated and the NMG (Numerical Master Geometry) system emerged, due largely to Malcolm Sabin and Arthur Kimbar. Essentially this is the system in use today throughout BAe. A 'civil' version of NMG was sold, in variants for aircraft, propellers and ships, in various parts of the world. NMG was used not only for aircraft external shape but for windshield fitting, seat layout and wiring design. A variant was sold by BAC, Warton to Rover cars in 1976 and is still in use. NMG was sold world wide. It was sold on from Norway to Russia via Japan 29. For output for machining, Profiledata Plus was introduced, with 'hooks' for input from NMG and enhancements for machining features such as pockets, When graphics terminals became available from Evans and Sutherland, IBM and ICL, an inhouse NC Graphics package was developed and was used for some years at Warton. As can be seen in case histories in some other industries, 1970 saw a business downturn in the aircraft industry and, according to a participant at the time, there was little further development throughout the 1970s. An exception was the HSA plant at Brough, which had assumed the responsibility of pursuing CADCAM development for all HSA sites and made good progress with a graphics design terminal 29. In 1970, the BAC initiative in NC hardware procurement passed to Filton because they expected a run of 200 Concordes. They followed development atWarton and opted for NC machines of US origin driven by APT.

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Profiledata, and with it Ferranti NC systems, was accordingly dropped by BAC; a blow which presaged the sale by Ferranti of its NC business. In the early 1980s, following the formation of BAe, D W Strang from the Concorde team at Filton was asked to review CADCAM on behalf of the merged group. After intensive appraisal, Hanratty's AD 2000 was chosen for its power in drawing piece-parts. It however lacked power in NC output and its internal handling of curved surfaces was considered inferior to NMG. A joint BAe/MCS team reworked the link to NC and added a link to NMG, renaming the system Anvil 4000. It is deployed on DEC/VAX through the Group, with Computervision retained at Stevenage for ~piece-parts and printed circuit boards 29. Hitch 29estimates that the cost of the Anvil CADCAM equipment serving 350 users is equivalent to the cost of 158 employees. A productivity of 1.45 would be needed to show a gain and 1.3 had been achieved. The CADCAM benefits are difficult to quantify, but BAe is committed. In the industry worldwide, data for manufacture has to be passed from a designing site to a manufacturing site in the same or another group. There are inhouse CAD systems as well as several vendor systems and so a substantial data exchange problem. In the European industry, systems used (in 1986) were: • • • • •

MBB - Cadam Aerospatiale- Computervision BAe - Anvil Aeritalia - Computervision Dassault - Catia

With a similar problem in the USA, the National Bureau of Standards encouraged the development of IGES and, in Europe, Aerospatiale began in 1983 to develop an exchange language SET. Both of these are now in use and are having reasonable success. Cal' indu$|l'y Needs Needs in the car industry are similar to those for aircraft except that the skins of the products are different. In car design, traditionally, the stylist is 'king' and must have a full size clay model. To generate a computer description, the surface of the model is digitized typically at 30000 points on one side of the car. Programs, aided by the designer interactively, fit smooth surfaces to the digitized points and a new, smoother, model may then be cut from polystyrene. Computer-aided car body design started with General Motors DAC-1 in 1963 and was immediately picked up by Ford Motor Company in the US and by Pressed Steel in the UK. The work which was started at Pressed Steel carried into British Leyland and now to Austin Rover Group (ARG); the Ford work continued worldwide. Ford The Ford Graphics System development in the USA was started in 1967 and continues today using Lundy displays and a Prime network. Software includes the

computer-aided design

Product Design Graphics System (PDGS) (a 3D wireframe package for sculptured surfaces), a Finite Element Analysis System (Fast) and an NC package for toolmaking (FINC). To make these available to its suppliers, Ford enteredinto a marketing agreement for Prime to sell and support them. Ford are not typical in choosing to have two CAD systems, PDGS for body design and Computervision Cadds 4X for the Power Train (engine and transmission), ARG and Jaguar each have preferred one system, (Cadds 4X), for both tasks. Ford feels that in having two specialised systems it gets additional benefits; and the amount of information flow between the two systems is low and can be contained. By 1982, at Ford, 100% of the exterior skin on a new model was being designed using CAD, and it is predicted that by 1991 all parts for new vehicles will be designed using CAD. The Ford Motor Company is organising a worldwide CADCAM database and plans that a new 'World car' will be designed in Europe and manufactured in both Europe and the USA. Using the worldwide database an engineer in one country will see a panel design from another country or continent,

Austin Rover Group (ARG) After a turbulent decade, Andrew Barr arrived at ARG as Managing Director in 1979 and resolved to use CADCAM as a tool for excellence in engineering. There was, as in Ford, more than one CAD system, IBM with Catia for body design, Cadam for tool engineering and Computervision for power train. Barry decided there should be a common system and a preferred supplier, Computervision was chosen and cooperated with ARG and Professor Bhattacharyya of Warwick University in the rapid development of the CAD facility. Barr u s e d CAD to help drive organisational changes, such as breaking or blurring the distinctions between designer and product engineer. An engineer at a terminal designs the panel, designing also the tool to make it, and so designs the panel in the way most suited to manufacture. The engineer and the stress analyst sit together at the terminal, While old cars, the Mini, and the Metro, remain on drawings, the Rover 800 was entirely designed by CAD,

Design

Analysis

Manufacturing Feasibility

using Catia initially and transferring to Cadds 4X. Paper drawings exist only as manufacturing information for those suppliers who do not have a CAD system. And as at Ford and Jaguar, ARG make presentations on CAD to their suppliers and have set a time-scale after which suppliers must take manufacturing information over a link between their CAD systems. Besides driving the company engineering function by the CAD facility, ARG plans a Linked Business System integrating all financial, costing, estimating and other functions by 1991.

Jaguar At Jaguar, a high degree of integration has been achieved via a CADCAM-based 'simultaneous engineering' approach. Figure 2 illustrates this new approach and compares it with the more traditional 'sequential engineering' route. To obtain the maximum benefit from the CADCAM approach a multidisciplinary project team approach has been adopted for new models. CAD is not thought to speed up the design phase itself but permits a vastly improved design with a higher degree of optimisation and allows 'design for ease of manufacture' to be incorporated at the conceptual stages. The significant improvements in lead times become apparent in the downstream activities of development and final production. Associated with the use of CAD a high degree of computer-based design analysis is being used and is fully integrated with the design activity. Examples are finite element analyses of body structures, suspension elements, etc and kinematic analysis of all complex mechanisms such as panel hinges, window winder mechanisms, etc. For a new model now being designed no manual drawings are being made. The interface with the major suppliers in Europe is being undertaken via computer magnetic tape. One particular supplier runs Catia on IBM and IGES is used successfully to link Catia with Jaguar's Computervision Cadds 4X system. In this particular case, the prototype parts have been manufactured by direct CNC methods.

Development

Tooling

Production

Traditional sequential engineering Time '

I

r'

CAD d e s i g n

Design analysis [ Manufacturing feasibility Validation I Soft tooled prototypes

Development

Hard tooling

Production

Reduced lead time

CADCAM-based simultaneous engineering

Figure 2. Comparison of 'sequential" and 'simultaneous' engineering volume 21 number 5 june 1989

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The future The car industry is well pleased with its CAD facility and is concentrating on better organisation and training to make use of it. It would like to get away from clay modelling for the stylist; it is technically possible now. The use of holography is being examined. Designers would manipulate freely in 3D, seeing a full size hologram of a car ~. 'The designer is a sculptor not a painter'. 3D drawing was tried in the1960s (the 'Lincoln Wand ':~2 and the Gregory 3D drawing box~), but did not lead to practical use. Car design still needs 3D drawing,

Ship design and production The design of aircraft, cars and ships share the way that concept design starts with an outer envelope followed by placement of major components within the envelope. The aircraft envelope is determined first by aerodynamics and structural attributes; aesthetics is low in priority. Whereas in car design, aesthetics is of paramount importance. In ship design as in aircraft design, the outer envelope is determined by the functional requirements, speed, range, load capacity, economy, manoeuvrability, sea-keeping. In addition the ship form may be a 'thing of beauty'. ~4 Any history of the aircraft and car industries is the history of leading firms in those industries. There has not in either industry been one single research or development body leading the way. Shipbuilding was different. The era of independent adhoc research ended in 1944 when the British Ship Research Association (BSRA) was formed, with Government financial support. With the appointment in 1963 of a new Director, Dr. Robert Hurst, from the Atomic Energy industry, the omens were fair for significant work on computer applications to the industry and to ship design in particular. By 1964 good progress was being made with computer applications to design calculations and the 'fairing' of ship's lines, in 1965, Hurst was drawn by the magnet of Sketchpad and sent Kenneth MacCallum to MIT to work on 'CRT and light pen' techniques. In 1966, MacCatlum was in the Centre for Computing and Automation at Imperial College, working on hull design, using Coons patches, manipulated interactively by light pen ~. In 1966, Michael Parker was selected to set up the Computer Division and at about that time the name Britships was given ~ to the package of programs then available for lines fairing, structural design and production of NC tapes using a revision of 2C, L augmented for shipbuilding BS.Hull definition at this time was by curve fitting in the three orthogonal plane sections ~7. Member firms could use whichever of the modular programs in the package best suited their needs and use of Britships was, by 1973, so widespread as to justify applying for a Queen's Award for technical innovation, which was given in 1974. From 1972 onwards a vastly more ambitious project, Ship Structural Design System (SSDS) was under discussion in the Association and a committee of shipbuilders and experts from the Admiralty Research

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Laboratory and universities reported on it favourably. The appropriate requirements Board (SMTRB) awarded a support contract and work started in 1974; G R Snaith 'without whose energy and eloquence the project would not have got off the ground ':~6was project leader with M I Todd as deputy and outside consultants contributing master-minding. The project was to be a leap forward from Britships and indeed was to leapfrog similar developments in Europe. It had a budget of £½ million pa (large for 1974), and a planned staff of 50. The work needed was seriously underestimated, however, and on the formation of British Shipbuilders, SMTRB support was withdrawn. After a review, British Shipbuilders decided that the industry was not ripe for such a system and instead a 'medium term solution' was adopted using elements of SSDS and Britships where appropriate. This development became known as Britships 2 and was undertaken jointly by BSRA and Swan Hunter Shipyards under Michael Parker and P D Forrest ~ 4,~. it was to build on developments in graphics hardware and was completed virtually on schedule in 2½ years. Hull form initial design and detailed definition used B-spline surface patches. It was a 'first' for shipbuilding systems in 'integrating in' a standard CADCAM package. The choice for this package of IBM-Lockheed Cadam meant significant work in interfacing to existing software, but provided highly developed interactive draughting. This novel use of Cadam involved the development teams in pioneering solutions to various problems. The success of BSRA software is indicated by $1 million of orders taken early in 1988 by the Washington Office of British Marine Technology from the US Navy, Coastguard and shipbuilding industry, as well as others from Canada4L

HAVE THE PROPHECIES BEEN FULFILLED? In previous sections, we first looked at what advantages were predicted for CAD and CADCAM and then at what isseentoday. Have thepropheciesbeenfulfilled? There were three prophecies. In the first prophecy Baumann and Coons, Feilden and Maddock, pointed to the way ahead, using CAD, as enabling: • greater productivity for designers • better design (more alternatives explored, more analysis) • shorter lead-times • follow-through to production The score on these seems to be three out of four. At APV-Baker, for example, productivity has increased three times and this is not an exceptional case. There are numerous examples of vastly improved design. Follow-through to production is general. But in exploring more designs, more thoroughly, the lead-time reduction has not been as dramatic as was forecast. Coons and the DAC-1 designers for example forecast a 75% reduction in elapsed time from conception of a new car to the supply of models to the showroom. But only about a 25% reduction has been achieved, albeit with vastly more design and analysis carried out.

computer-aided design

The second prophecy was that the 'upstream' computer-held designs would feed all the other functions of a manufacturing company, as urged for example by Wallace ('Limited Business System') and earlier by de Ferranti. Positive steps in this direction are seen, as noted earlier, for example, as the Ferranti Scottish factories and at APV-Baker, but it is a very slow evolution and may take another ten years to achieve fully. Williamson proposed the third prophecy, that the 'top 5%' of designers would contribute programs to a 'national CAD network' and the 'other 95%' would, by using these programs, draw on the knowledge and skill of the 5 %. There are now some exercises in 'expert' system applications to CADCAM but this is not what Williamson envisaged. The 95% have not been given design programs written by the 5%. They have instead been given superlative tools with which to apply their creativity, to produce their own designs. And in a significant number of cases, some of the 'top 5O/o' of engineering product designers have moved sideways into designing the CAD tools. The '950/0 ' have gained fromthe'5%'inaratherdifferentwaytothatproposed by Williamson's precept. Particular cases are seen in the several talented people who left the CAD Centre and university groups to form new companies designing and selling CADCAM systems. It can now be seen in fact that the greatest effect of the CAD Centre was 'virtual' or 'vicarious'. Following its partial dissolution in the late 1970s, before privatisation, talented energetic people set up new companies which shortly became major suppliers of the 'glass drawing boards' and other excellent tools. A project (PDMS) in the CAD Centre was a precursor for a product sold by one of these companies, a CADCAM workstation which has transformed drawing offices and has annual sales of $200 million worldwide. History has shown the planners, prophets and preceptors of the 1960s were pointing the right way in urging the merits of CAD and in setting up the CAD Centre. The unwitting effect of those who, in the 1970s, criticised the Centre, and of those who, because of that criticism, privatised themselves, has contributed largely to present success, It has been an interesting and exciting history to live through.

engineering design' Comput.-Aided Des. Vol 10 No 2 (1978) 2 Coons, S A 'An outline of the requirements for a computer-aided design system' Proc. AFIPS,Spring Joint Comput. Conf. (1963) pp 299-304 3 Farin, G 'Trends in curve and surface design' Comput.-AidedDes. Vo121 No 5 (1989) pp 293-296 4 Coons, S A 'Surfaces for computer-aided design of space figures' MIT MAC-TR-41 (June 1967) 5 Feilden, G B R (Chair) Report of a Committee Appointed by the CSIR to consider the Present Standing of Mechanical Engineering Design HMSO (1963) 6 Anon Draft of Computer-Aided Design Section of Automatic Design Subcommittee Report NEL (June 1965) 7 Anon Report of meeting on 7th December, 1965 at the Rembrandt Hotel NEL (Report No 242) (August 1966) 8 Williamson, D T N Computer-aided design, a proposed programme of development Molins Machine Company Ltd (February 1965) 9 Maddock, I (Chair) Report o! the Minutes of TechnologyWorking Party on Computer-Aided Design Ministry of Technology (June 19.66) 10 Penny, F D (Chair) 'Computer-Aided Design Committee' First Annual Report (1967-1968) 11 Maddock, I Letter to members present at last meeting of Committee (18th November 1969) 12 Sabin, M Personal communication (March 1988) 13 Gott, B Personal communication (March 1988) 14 WUliamson, D T N The achievement of CAD objectives (January 1976) 15 Wallace, J F 'A linked engineering business system' MEMTRB CAD Steering Group Report (October 1976) 16 Clayton, R S 'Computer aided design and manufacture' Cabinet Office, ACARD Report HMSO (1980) 17 Braid, E C Designing with volumes Cantab Press

ACKNOWLEDGEMENTS The writing of this paper has taken the form of a 'structured walk' back through the years, revisiting scenes and people, some, pleasurably, there to talk to, some sadly no longer contactable. Many have given their time generously for my visit and in afterwards correcting my references to their firms. I would like to give very special thanks to Charles Lang, lan B r a i d , Brian Gott, Crispin Gray, Harry Hitch, Robert Hurst, Michael Parker and John Wallace.

REFERENCE8 1 Elliolt, W S 'Interactive graphical CAD in mechanical

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(1973) 18 Effective CADCAM'87 Towards Integration Conference Proc. Institute of Mechanical Engineers (November 1987) 19 Ortony, A 'A system for stereo viewing' Comput. J. Vol 14 (1971) p 140 20 Ellio,, W S and Armit, A P 'An interactive threedimensional system for preparation and checking of structuralidealisations'ProceedingslFIP/IFACInt. ConL Computer aids in ship design and shipyard automation North Holland (1976) pp 225-232 21 Licklider, J C R 'A picture is worth a thousand words - and it costs ...' Proc. AFIPS Spring Joint

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Computer Conf. (1969) 22 Okino, N, Kahaja, Y and Kuko, H 'TIPS-1 Technical Information Processing System' Proc. 2nd IFIP/IFAC Int. Conf. Programming Languagesfor Machine Tools North Holland (1973) 23 Baumgart, B G Geometric modelling for computer vision Stanford Artificial Intelligence Laboratory (1974)

Proc. Inst. Mech. Eng. 200 B2 (1986) 31 Axe, R 'CAD in British industry', Roy. Soc. of Arts J. (March 1988) pp 249-261 32 Robert, L G 'The Lincoln Wand' Proc. FallJ. Comput. Conf. Spartan Books (1966) 33 Gregory, R L 'Drawing and tracing in 3 dimensions - stereo scribe' Perception Vol 4 No 2 (1975) pp 221-228

24 Braid, I C 'Six systems for shape design and representation - a review' Cambridge University Computer Laboratory CAD Group Document No 87 (1975) 25 Hitch, H PY 'Computer-aided design in mechanical engineering in the UK - an overview', Proc. Symp. Comput. Aided Des. in Mech. Eng. Politecnico di

34 Hurst, R 'Shipbuilding in the future' Phil. Trans. Roy. Soc. No 273 (1972) pp 13-21 35 McCallum, K J 'Surfaces for interactive graphical design', Comput. J. Vol 13 No 4 (1970) 36 Darling, R F Forty years of progress - a history of the Wallsend Research Station: 1945-'1985 (1985)

Milano, Italy (1976) 26 Gossling, T H 'The 'DUCT' system of design for practical objects' Proc. Syrup. Comput. Aided D e s . in Mech. Eng. Politecnico di Milano (1976)

37 Hurst, R 'Britships - an integrated design and production system' Proc. First Int. Symp. on Computer Applications in the Automation of Shipyard Operation and Ship Design North Holland (1973)

27 O'Neill, R A 'CAM-X at Otter Controls' Comput. Aided Design Vol 17 No 4 (1985) pp 149-152

38 Forrest, P D and Parker, M N 'Steelwork design using computer graphics' Trans. R.I.N.A. (1982)

28 Jackson, R H Achieving effective CADCAM. Ten years of experience at Baker Perkins Baker Perkins PMC Ltd, Peterborough, UK (October 1987) 29 Hitch, H P Y Private communication (31st March 1988)

39 Parker, M N, Odabasi, P A, Fitzsimmons, P A and Goggin, C J Advanced technology in ship design analysis and production American Society of Naval Engineers,ASNE Day (1984) 40 Parker, M N Private communication (6 June 1988)

30 Hitch, H P Y 'CADCAM in the aircraft industry'

41 BMT Newsletter (Spring 1988)

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