Tooling is a major component of cost in virtually all manufactured goods. A complex product such as an automobile requires hundreds of custom molds and dies to shape and form the many metal and plastic parts from which it is constructed. The machining, polishing and heat treatment operations required to build a tool are capital equipment and energy intensive. Similarly, the melting, casting and forging operations at the steel mill leading to the finished tool steel stock material that is machined are also equipment and energy intensive.

New approaches to building molds and dies that reduce their cost and lead time are attracting a great deal of attention recently. One approach, spray deposition, combines rapid solidification processing and near-net-shape materials processing into a single step. The general concept involves converting a mold design described by a CAD file to a ceramic tool pattern via a suitable rapid prototyping process. This is followed by spray depositing molten tool steel onto the pattern to replicate its shape and surface detail. The resultant metal block is cooled to room temperature and separated from the pattern. Typically, the deposit’s exterior walls are machined square, allowing it to be used as an insert in a standard mold base.

When processed in this way, conventional ferritic tool steels can display unique features such as metastable phases and the suppression of carbide precipitation and growth. This imparts the ability to tailor the steel’s properties using a relatively low temperature artificial aging heat treatment, thereby providing a heat treatment option to the conventional austenitization/quench/temper cycle. This paper summarizes processing steps, energy expenditures, and material properties of tool steels processed conventionally and by spray deposition.