The Development of Computer Aided Design and Manufacture - CADCAM

35 Years of Research and Development


D.B. Welbourn FREng

In March 1965 Donald Welbourn heard a lecture to the Engineering Society by Strachey of the Mathematical Laboratory (now the Department of Computer Science) on the early work at MIT on Computer Aided Design (CAD). He was so fascinated by this that the following morning he caught the Head of the Cambridge University Engineering Department, Prof. J.F.Baker (later the Lord Baker of Trumpington) in the tea-room, told him about it, and said that we must get started in this field. Baker was enthusiastic, and by the end of the year, the Science Research Council had awarded Baker and Welbourn a grant of £65,000 with which to start work on CAD.

Initially work was done on the PDP11 graphics computer, which Prof. M.V.Wilkes (later Sir Maurice) had bought in 1965 for the Mathematical Laboratory (for £45,000 with 8k memory!!), and a joint team was formed under the leadership of C.A.Lang, who had taken the Mechanical Engineering Sciences Tripos, and then worked at MIT with S.A.Coons. The first research student was A.R.Forrest, who tackled the problem of how to define the blended intersection of two cylinders. A dozen or so firms were persuaded to second engineers to work with the team. The conceptual breakthrough of defining objects in terms of 3D reference lines, analogous to the draughtsman's centre line, together with cross-sections normal to them, was produced by S.Matthews, seconded by the Ford Motor Co. A full account of this early work on what became known as the DUCT CADCAM program, is to be found in "The Design of Mechanical Components and the Development of DUCT" by Donald B.Welbourn in Band 16, No.3, April 1983, published in the Arbeitsberichte des Instituts fuer Mathematische Maschinen und Datenverarbeitung (Informatik), Universitšt Erlangen.. In passing, it may be noted that DUCT was not an acronym (although later people pretended that in meant Design Using Computer/Cambridge Technology!) but was thought up in the tea-room one morning, when S.Matthews and P.J.Payne were designing inlet manifolds and other duct-like components.

Time-sharing facilities on an Atlas II computer also soon became available to the CUED through the Cambridge CAD Centre, which had been formed by the Department of Trade and Industry (DTI) to develop the work which the University was doing. However, when this service dried up, Dr.R.B.Morris, an Assistant Director of Research in the CUED, obtained free time-sharing computing facilities on-line to a commercial time-sharing computer, which enabled work to continue. Initially an ITT bureau using an IBM computer, it was later taken over by the Control Data Corporation.

In 1972 the CUED was able to obtain two 3-axis n/c machine tools with a DTI grant to help the m/c tool industry, thus enabling the work in CAD to be expanded into CAM. One of these, a Hayes milling machine, went onto the firm's stand at the Machine Tool Exhibition at Olympia that Autumn, and thanks to a sterling effort by P.J.Payne, a jug-like object, was cut on the stand. This was probably the first ever public demonstration of 3-D CADCAM at a machine tool exhibition.

Meanwhile, in 1971, Donald Welbourn had become Director in Industrial Co-operation and Director of the Wolfson Cambridge Industrial Unit. He persuaded the Pye Foundation to support T.H.Gossling, a member of the Unit, in developing DUCT. Control Data had also become interested in the work, seeing it as a front end for creating Finite Element meshes. As a result of this industrial support, Welbourn, who had become a member of the Mechanical Engineering and Machine Tool Requirements Board of the DTI, had been able in 1974 to get a grant from it for Dr.R.B.Morris and Dr.J.Matthewman to continue developing DUCT. The Science Research Council had said that this work was no longer research, while industry was saying that a lot more development was required. Morris recruited two very able Cambridge graduates, P.W.Olding and A.L.Johnson., and the work was proceeding well, when both Morris and Matthewman applied to go on Sabbatical Leave for 1976/77. Faced with a potential disaster vis-ŗ-vis the DTI, Welbourn took the direction of the work back into his own hands. and started systematically to test the programs, and the instruction manuals. This resulted in a quality of handbook which was partly responsible for VW and Daimler-Benz taking licenses for DUCT, since they said that they had never seen such clear instructions produced by any firm, let alone by a university.

Welbourn never did any of the programming in connection with the work, but made it his job to set targets for what needed to be done, to get money and to get able staff to do the work. In the early stages of the work, up to the oil crisis of 1973, he had got a dozen or so firms to second men to work with the team in Cambridge, thus enabling the firms to get experience of CAD without having to find the capital for a dedicated computer. After the crisis he had little success in this, with one notable exception. In 1974 he persuaded the late Lord Caldecote DSC, Chairman of The Delta Group plc, and a former member of the staff of the CUED, that his companies must get involved with computer aided engineering. Delta seconded E.B.Lambourne to work with the Unit for two years while taking an M.Sc. In 1977, after Lambourne's return to Delta, Lord Caldecote founded a new subsidiary, Deltacam Ltd., to advise on CADCAM and to supply time-sharing services to other firms in the group. The Managing Director was H.R.O.Humphreys, E.B.Lambourne became the Technical Director, while the Main Board member responsible was Dr.R.B.Sims. He supported the company enthusiastically.

By the end of 1973 and the beginning of 1974 a number of firms had paid the WCIU to make simple tools for them. it. One was the mould for a spectacle case (Fig.1). Another was for George Fisher Ltd. of Bedford, which placed an order for a core mould, that was still in use 10 years later (Fig. 2 & 3). These were probably the first industrial tools, other than those for automobile bodies, to be made using CADCAM. They were both programmed by T.H.Gossling, and made in the CUED workshop.

Click on images for more detail
1.Spectacle Case


2.Core  Mould  th-duct3.jpg (7969 bytes) 3.Malleable iron component

As a result of these successes, and also work in collaboration with Perrys of Leicester on engine ports and manifolds --- its Sales Manager G.M.A.Cox had become a firm backer of the work --- , Welbourn organised in 1974 the first large scale attempt to get industry interested, and arranged in the CUED a one day seminar for the pattern- and tool-making industry to show some of the early work which had been done for individual firms. This inspired J.J.Harvey, one of the leading toolmakers in the country, and a man with a world-wide reputation, to get interested in the work, and to follow Delta as the second DUCT licensee. He also persuaded some trade union leaders to visit the WCIU to see what the future might hold. Otherwise the attitude was one of wait and see. This was however followed in quick succession by a number of other successful tools for various firms, each of them setting theoretical challenges which forced the development of DUCT in a pragmatic manner. By June 1976, the DUCT program had settled down enough for it to be designated Mk.1

In 1977 the inlet and exhaust port cores, Fig. 4, were designed by Olding for the new British Leyland "O" series engine through the good offices of G.M.A.Cox of Perry's.. However, the only person in Leyland who understood what was being done retired early in disgust at the lack of interest in the firm, and all contact lapsed. This job, however, had revealed the fact that nobody understood the geometry of split lines, but by the end of 1978 D.P.Sturge had cracked the problem of designing split lines with draft angles for tools, a world first.

th-duct4.jpg (10889 bytes)

4.Exhaust Port Cores

Just at this moment, though, VW, at the instigation of Control Data, on whose time-sharing bureau in Brussels the development of DUCT was now being done, sent two engineers to see us, bringing challenge drawings with them. They were staggered when Sturge was able to program them, and the workshop was able to cut the model for a complex core, Fig. 5, and also of a drag link, Fig. 6, within the couple of days that they had allowed for their visit. A Finite Element mesh was also created for the drop-link, and weight calculated. VW was the only firm in the early days to test all of DUCT's capabilities. As a result, VW took a license in 1978, and paid the WCIU about £20,000 for further developments, a lot of money in those days.

th-duct5.jpg (10232 bytes)  

5.Model for a complex core 

th-duct6.jpg (10750 bytes) 6.Drag link

At the end of 1977 Welbourn had given a paper in Zurich at an European Economic Commission seminar, and this was published in 1978 in an East German (DDR) foundry journal, which in due course landed on the desk of the director in charge of the foundry and forge at Daimler-Benz in Stuttgart. He was hopping mad that the East Germans had been told about these things before the West, and demanded of Control Data that Welbourn should come over to Frankfurt to demonstrate DUCT to them. As a result of this visit, and the manufacture of a challenge object, Fig. 7, Daimler-Benz, now DaimlerChrysler, took a license in November 1979 to test DUCT Mk.3.2. The manifold was programmed by Sturge; it has an unusual blend on top. Early in 1980 two of their engineers came over to Cambridge to see what resources were behind DUCT, and were astounded to find that while the WCIU only had 4 people working on the development, it was achieving results which Computervision, with 250 working on it, were failing to obtain. By August of 1980 Sturge's redesign of DUCT, Mk.4.0, could be delivered. Another result of the EEC conference had been that Sulzer Bros. in Switzerland had taken a time-sharing license on the CD bureau.

th-duct7.jpg (15822 bytes) 7.Manifold

The problem of intersecting two cylinders, whilst providing blending between them such as pattern-maker provides, had been the original topic tackled by our first research student, A.R.Forest, now Professor of Computing at the University of East Anglia, but not until 1977 did E.B.Lambourne find a fairly general method found for doing this with two DUCTs. The general solution, again a world-wide first, was found in 1978 by Dr.Ing. Michael Galwelat, a German engineer seconded by Control Data to work in the WCIU.

The whole development of DUCT might have suffered a bad hiccup in 1979 when A.L.Johnson, who had been energetically leading the team, became a lecturer on the staff of the CUED. However, Dr. D.P.Sturge, a graduate of the CUED, had joined the DUCT team in April 1978, and was available to take over its leadership. By 1979, with extensive experience being fed in not only by Deltacam, but also by VW and Daimler-Benz (Mercedes), he realised that the whole system needed to be rethought, and brought to bear on the problem a brilliant theoretical and practical brain. Greatly assisted by M.S.Nicholls, he rapidly produced what became known as DUCT Mark IV. In due course Sturge was to move with the team to Delcam International plc, and despite illness, continues (Apr 2000) to contribute original ideas to the further development of the work. With Mark IV, the designer or toolmaker was given the possibility of describing literally anything, even if at times endless ingenuity was essential.

By 1982, 16 years after the start of the work, the commercial success of DUCT was becoming nearer, since Compeda Ltd., a firm set up by the government to develop and license university software, was supporting the research and development team in the WCIU, and was setting out to license DUCT both in the USA and Germany. Just as it had tendered to supply DUCT on IBM computers to Daimler-Benz, Mrs.Thatcher insisted on selling-off all government firms, and Prime Computers in the USA bought Compeda for its pipe-work package. Prime took no interest at all in DUCT, which it had also acquired. After two years of wasted time, the WCIU regained control of the program, and in January 1984 Deltacam Ltd. took over its development and licensing, together with the Cambridge team, which continued to work in Cambridge..

The Delta Group plc, after the retirement of its Chairman, Lord Caldecote, lost interest in its subsidiary. As a result, in January 1989 Humphreys and Lambourne courageously negotiated a management buy-out to form the firm of Delcam International plc, a large proportion of the capital being held by the staff, by then about 70 strong. Since then the growth in the number of licensees has followed a cube law when plotted against the years, and today (March AD2000) more than 3500 firms are licensed world-wide in some 50 countries. Delcam employs about 200 people in its purpose-built building in Small Heath, Birmingham, this number including a 20 man tool-room. The firm also has 71 agents and subsidiaries based in 47 countries selling its products world-wide. For more information visit

One reason for Humphreys and Lambourne being able to have such confidence in DUCT, and the firm which they were taking over, is illustrated by the fact that in 1985 VW was able to program and manufacture the gear case shown in Fig. 8, saving 10% of the weight compared with an "identical" gear box made using conventional techniques, and doing so in half the time. With no other CADCAM program was anything of this sort possible at the time.

th-duct8.jpg (12178 bytes) 8.Gear   Case

If the impression has been given that DUCT was only of use to the large firm, Fig. 9, shows a two-cavity moulding tool for a complex rubber hose for an automobile programmed and manufactured in the then 17 man firm of August Weber GmbH of Hildesheim by a programmer who had served his time as a patternmaker.

th-duct9.jpg (16477 bytes) 9.Moulding Tool

Now, in AD2000, with the coming of windows techniques and the possibilities which they offer, the name of DUCT is being phased out, and the program has been separated into a family known as the PowerSOLUTION family of programs, PowerSHAPE for design, PowerMILL for manufacture, and PowerINSPECT for inspection. Other programs developed by Delcam, such as ARTCAM, which owe nothing to the Cambridge work, are also proving successful.

th-duct10.jpg (15929 bytes) 10.Aircraft Cabin Serving Dish

Everyone who flies today is familiar with one result of the work which started in the CUED in 1965, the dishes from which they eat in aircraft (Fig.10). Almost certainly, if you turn one over, you will find a star, meaning that it was designed, and the tooling for it made, by de Ster of Belgium using DUCT or its POWER successors. For more, see

D.B. Welbourn


1 Spectacle case made from a mould designed by T.H.Gossling, and made in the CUED workshop

2 Core Mould for George Fisher of Bedford, designed by T.H.Gossling, and made in the CUED workshop

3 Malleable iron component made using cores from the above core mould.

4 Cores from moulds for Rover "O" Series engine designed by P.W.Olding and made in the CUED workshop

5 Actual VW manifold, and 1/2 scale core mould designed by D.P.Sturge and made in the CUED workshop

6 Drop-link for VW designed by D.P.Sturge and cut in the CUED workshop. An FE mesh was also produced.

7 Manifold for Daimler-Benz with split line, and unusual blend on top, programmed by D.P.Sturge

8 Gear case designed and made in 1985 by VW, Braunschweig, using DUCT.

9 Mould tool programmed and made in 1995in the 17 man firm August Weber Modellbau GmbH, Hildesheim.

10 Tray, mug and dishes designed and made by de Ster, as seen on the computer screen.