Rapid Prototyping Methods

Leander F. Pease III, Powder-Tech Associates, Inc.

If every designer had immediate access to the required raw material, computer-controlled machining centers, and the facilities for heat treating and finishing parts, the prototype process would already be irreducibly short. It is the real-world lack of immediate access to raw material and machining that has inspired the search for desktop manufacturing (DTM). In its most elegant form, the engineer's CAD system drives a clean, quiet machine in the corner of the office to produce the required prototype part the same day, and, for some classes of plastic materials, this kind of system is in use today. A laser system traces out the part in a bath of photocurable plastic. In the past, it was not common practice to machine a plastic prototype part from a monolithic block. Rather, the usual procedure was to build tooling and then injection mold the part, a process that could take up to 12 weeks.

The rapid development of laser-processed plastic prototypes has inspired the search for a similar system to work with metals. The output of such a system might be fully dense parts to simulate the product of ingot metallurgy, or it might be less than fully dense materials that simulate P/M components. Whatever the system, it must offer advantages over the current machining methods. Such advantages can be in saving development time or reducing machining costs. It is important to understand the current methods used in P/M part prototyping so as to be able to assess the real value of the developments in DTM.

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