One of MTT Technologies', formerly MCP Tooling Technologies Group, newest prototyping systems has been used in the production of the Bentley Soapbox Team’s entry at the Goodwood Festival of Speed. The vehicle came second in what is one of the most popular events at the Festival - a great result for the whole team!
Anxious to compress the time between production of CAD data and finished parts, Bentley’s Head of Concept Design, Jim Shaw, who is also team designer and driver, invited MTT Technologies to become involved in the production of around 20 mechanical parts for the vehicle. This led to key components of the vehicle’s suspension system being produced using MTT's new Nylon Vacuum Casting System (http://www.mtt-group.com/nylon-vacuum-casting.html).
The process is already being used commercially by several major automotive manufacturers and is a brand new technology. It enables Nylon parts to be produced in a matter of days without the need for injection moulding and the associated cost and lead time required for the production of steel tooling which makes it ideal for producing quick prototypes and for low volume production runs.
Unlike generative processes which produce porous, sintered Nylon prototypes from powder, MTT's Nylon Vacuum Casting System produces fully dense parts in Nylon 6 - including those with complex geometries and thin wall sections as thin as 0.3mm. Current commercial applications include living hinges, automotive air inlet manifolds, trims, brackets, and electrical housings. When Nylon parts are required for crash testing purposes, they can be produced in a matter of days using this process.
The Nylon Vacuum Casting process has evolved from the standard MTT vacuum casting process and involves casting a master model in (the soapbox models were SLAs produced by rapid prototyping,RP, from from CAD data) silicone rubber to produce a mould (http://www.mtt-group.com/vacuum-casting.html). This is a 6 – 12 hour process depending on mould size. Using MTT’s Nylon Casting Module in a conventional vacuum casting machine, the nylon material is then cast in a vacuum environment into the silicone mould. De-moulding takes place after just 6 minutes and parts demonstrate mechanical properties of those which have been injection moulded in Nylon PA6. A range of comparative technical data on the several different Nylon formulations is available on request from MTT.
The largest soapbox component produced by MTT was the metal suspension yoke or carrier, which was made using MTT's Metal Part Casting process . The yoke was a large complex part with many thin wall sections. A silicone mould was produced from the SLA master which was then used to vacuum cast wax to produce a wax model. MTT Metal Part Casting utilises the investment ( lost wax ) process which involves the encapsulation of the wax model in ceramic under vacuum, melting out of the wax, and then filling the cavity with metal, in this case aluminium. The whole process can be achieved in less than 72 hours and produces highly accurate castings in zinc, aluminium, bronze or brass.