The MTT Vacuum Casting Process Combined with the MTT Metal Part Casting Process.

GM Automotive combines two MTT Technologies to produce fast, economical high quality metal parts. GM has now compared all rapid prototyping and rapid manufacturing processes for producing low cost metal parts quickly and accurately.

The benchmarking requirements GM put forward to all its suppliers were exact and straight to the point.

The part to be produced, an aluminium electric air control valve, needed to fulfil the all the following requirements:

- Production material: (aluminium) in all the common alloys
- For quantities of 5 - 50 components
- No more post processing than with production manufactured parts
- Parts need to be tested and approved by GM customers
- Components to be supplied in less than 3 weeks
- Lowest unit price possible

Taking into consideration the following requirements: unit price, timing, total cost, tolerance and surface finish, the combined MTT Processes of MTT Vacuum Casting*** (for producing the silicone moulds and wax castings) and MTT Metal Part Casting came up with the required results.
2 weeks for 20 production quality valves at a total cost of only 10.000 Dollars.

The GM Case Study for Rapid Prototyping and Rapid Manufacturing of 20 Electric Air Control Valve Parts in aluminium.

Process	Models, Moulds or Tooling (US Dollars)	Unit Price (US Dollars)	Timing (weeks)	Total Cost (US Dollars)	Tolerance	Surface finish in RA
Machine from solid Aluminum	None	1,200,00	4 - 5	24.000	± 0	0.5
Plaster casting	8,000	100,00	6 - 8	10.000	± 0,6 mm	2 -3
Investment Casting / Graphite*	8,000	50,00	6 - 8	9.000	± 0,3 mm	4
Direct Shell** Production Casting (DSPC)	19,000	145,00	4 - 5	21.900	± 0,5 - 0,7 mm	5 - 7
MTT Vacuum Casting plus MTT Metal Part Casting	2,000	400,00	2	10.000	± 0,5 mm	2
Die casting in steel Tools	approx. 100,000	2,00	25	approx. 100.000	± 0,36 mm	0.5 - 1

* Machined graphite molds for producing waxes
** A generative, additive fabrication process


*** The MTT Vacuum Casting Process, formerly MCP Vacuum Casting, is a leading rapid manufacturing technology for producing fast, high quality prototype and medium run mouldings in plastics. The complete range of over 30 materials covers filled and unfilled Nylon PA6, non- mercury PU based vacuum resins and epoxies and also silicones for producing silicone mouldings.

For more information or to test and benchmark one of MTT's Processes please contact through MTT's website www.mtt-group.com.

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