ABSTRACT
In plastics, prototypes can be machined from rod or slab stock, or injection molded in an inexpensive single-cavity mold made of aluminum, mild steel, or epoxy steel. Progress of the machining work can be followed closely, and obstacles that may be encountered as the work proceeds can possibly be overcome by small changes in design that can be suggested on the spot. Preproduction tooling is the ultimate approach to prototyping. It allows the duplication of production parts precisely with respect to shrinkage, warpage, molding cycle, and properties. On a short-term basis, preproduction tooling probably is the most expensive of the various routes to obtain prototype parts, and it requires more time; but in the long run it usually is the preferred route. Successful molding of plastic prototype parts in die-scast molds requires a thorough understanding of the benefits and limitations of the useful method.
