CARP

From: Jon Hunwick (Delcam  International PLC)
To: RP-ML
Date: Tuesday, July 26, 1994
Subject: CARP
Hello again everyone.
     My message of yesterday, which was really intended as an information request, seems to have 
generated a fair amount of interest so I'll tell what CARP is all about, who the partners are, and what we 
have achieved to date.
     CARP is funded by the UK DTI (Department of Trade and Industry) under the banner of Eureka! 
which aims to promote joint R&D ventures by UK and European companies. In the case of CARP, there 
are eight partners, although along the way we have formed 'strategic alliances' with other companies. 
Those 8 partners are:
  Ricardo - A UK company who are specialists in engine design.
  Leeds University - Teaching and research
  Gillardoni - An Italian manufacturer of motorcycle cylinder heads
  Magnesium Services - Magnesium alloy die-casting and design
  CADDETC - UK CadCam Data Exchange Technical Centre
  Volkswagen - German car manufacturer
  Delcam International - CADCAM (DUCT) developers
  Webster Mouldings - Trade mould and tool makers
     As can be seen from the above list, the project has a fair spread of interests, although the main thrust is in automobile engineering and design.
     The first phase of the project was to examine the various Rapid Prototyping machines - we call them 
FFFF (4F) - Fast Free Form Fabrication. A bench mark object was defined which had all the 
manufacturing features the various partners were interested in. These included thin walls, tapers, slots, 
holes (as small as .5mm), and free-form surfaces. Models were 'grown' or 'built' by all the vendors (12 in 
all) and these models were measured. The results of this test are available, and were given at this years 
Rapid Prototyping conference at Nottingham (UK). The results were, in fact, pretty much as you would 
expect, with the liquid systems being more accurate for small details, but the solid systems being better for larger parts. As a result of the tests two machines were purchased. A DTM Sinterstation is now installed at Leeds, and a Helysis LOM at Websters.
     Another main area of work has been in upgrading the ability of the various partners to generate good 
quality STL files. Up to now the best Meshes come from solid modelling systems, such as Pro-E, HP Solid Designer etc. DUCT (the CadCam system provided by Delcam) is a surface modeller, and is in use at 5 of the partners, although other systems (UGII, CATIA,CADDS5) are used by others in the consortium. Traditionally manifold meshes have been tricky (at best) to extract from surface models. Delcam have, therefore, completed a set of tools which can take non-manifold meshes (provided they represent a closed object) and fix them. These tools are now in regular use, and we can take a part from IGES and make it FFFF ready in under an hour.
     Apart from simply building models, one of our main interests is in getting metal parts. To this end we 
have made a strategic alliance with a foundry in Wales, who are now able to take a DTM or LOM model 
and cloak it in ceramic slurry. Once fired, this produces a 'shell' mould into which molten metal can be 
poured. The ceramic is then broken away, and the metal part extracted. In this way we have succeeded in 
producing parts in both aluminium and stainless steel. Admittedly the FFFF model is destroyed in the 
process, but the point is that you get a prototype metal part for test 3-4 weeks earlier than with traditional methods. 
     The next phase of work will be to tighten up the design/optimization loop at the beginning of the 
process. Ricardo produce a CFD (Computational Fluid Dynamics) system called VECTIS. From the initial CAD data, a mesh is generated which will be read into VECTIS for analysis. Results of that analysis will be fed back to the designer who will modify the design. This process may iterate a few times until the 
design is optimal. A FFFF model will be produced, cast off, machined, and (in the case of engine 
components) actually run. This phase of work promises to be very exciting, and we are all looking forward with anticipation!
     I hope this has filled in enough of the blanks for you. If not, just ask, and I'll tell you what I can.
                  "Thankyou for your cooperation"
Jon Hunwick