Machining, Mold Materials, and Heat Treatment

This section is not meant to be a guide for the actual machining operations, but gives some descriptions of the evolution of machining in mold making. Earliest mold components and plates were produced by first sawing the raw blanks from steel plates of the appropriate thickness bought from the steel mill, with reciprocating or (endless) band saws. The next step was then squaring and/or rough machining these blanks—mostly plates, but also blanks for cavities—on shapers, with the blank held solidly and a single cutting tool moving back and forth over the surface. This slow method was abandoned in favor of rough grinding with special, large grinding machines or milling with large cutting heads in vertical or horizontal milling machines. Both these methods are now used extensively. Since this requires large, expensive machines, which smaller mold makers cannot usually justify economically, a service industry developed, specializing in the machining of the—often large—plates; this was the origin of the mold supply houses such as DME, National, Hasco, and others.