MATERIALS -- METALS
Joseph J. Beaman
Rapid prototyping can be used to create metal parts by fabricating patterns for casting applications, as Chapter 10 describes. This chapter describes processes that create metal parts and tools in a more straightforward fashion. A major proposed application for these processes is metal tooling, especially injection mold tooling.
Various nomenclatures are used to describe rapid prototyping processes that create metal objects. At the University of Texas, the three major metal processing methods are called transfer methods, indirect methods, and direct methods.1 In simple terms, transfer methods use patterns -- either castings or spray metal patterns (this JTEC/WTEC panel did not address the subject of spray metal). Indirect methods (which could also be called low-density matrix methods) involve making relatively low-density metal objects and then infiltrating or post-sintering these objects to high density. Direct methods (which could also be called high-density methods) create high-density metal structures without a secondary processing step. There are already commercial applications of the indirect methods; the direct methods are all still in the research stage.
The United States has strong research and commercial activities for creation of metal tooling by rapid prototyping techniques. Europe also has very strong research and development programs in both direct and indirect metals processes. In addition, Europe is creating a broad-based technological infrastructure for this work. The coordinated programs of Germany's Fraunhofer Institutes are particularly effective. The panel is aware of no indirect or direct rapid prototyping metals research or development work in Japan, except for that by Nakagawa, which will be discussed in the Japan section of this chapter.