Selective Laser Sintering of Metal Molds: The Rapidtool Process

Complex three dimensional parts can be manufactured directly from CAD data using rapid prototyping processes. SLS® Selective Laser Sintering is a rapid prototyping process developed at the University ofTexas at Austin and commercialized by DTM Corporation. SLS parts are constructed layer by layer from powdered materials using laser energy to melt CAD specified cross sections. Polymer, metal, and ceramic powders are all potential candidate materials for this process. In this paper, a commercial SLS process - the RapidTool Process - which allows metal molds to be rapidly manufactured is described. With this process, a polymer coated carbon steel powder is used to fabricate a "green part" in the SLS machine. The green part is then placed in a furnace with blocks of copper and, in a single furnace cycle, the polymer coating is removed and the steel skeleton is infiltrated with the copper. The resulting steel/coPPer composite material has durability and thermal conductivity similar to aluminum and can be hand finished using standard techniques. A finished mold core and cavity set which can be used to mold at least 50,000 parts with most plastics can be prepared in approximately ten days. The cost to produce most mold geometries with the RapidTool Process is also comPetitive with traditional mold-making methods.Mechanical Engineerin