Tomorrow's molds and patterns will, of necessity, be made of tougher and more exotic materials to increase production and hold closer tolerances. In addition to better wear, molds must be repairable, have greater consistency, and be made with shorter lead times. Materials, such as stainless steel, H-13, 4140 and D-2, are replacing the traditional cast irons for permanent molds and sand cast patterns, and, in some instances, graphite molds are replacing sand molds to increase production rates. New and exotic materials used for tooling require different machining methods. Electrical Discharge Machining (EDM) is rapidly gaining acceptance for machining permanent molds, semi-permanent molds and sand cast patterns. EDM notably reduces bench time and finishes tough alloys faster than milling machines. Until recently, the cost to produce electrodes (graphite that is machined in the shape of the impression and used in the EDM to spark-erode the work piece) was expensive. Advancements in the abrading process (a method of form grinding electrodes with the use of an abrasive-surfaced epoxy cutting master) have sharply reduced time and the amount of graphite needed to produce electrodes. Simultaneous engineering to reduce lead times and costs is possible when abrading and EDM are used in conjunction with rapid prototyping. Laminated Object Manufacturing (LOM) and Stereolithography (SLA) systems can be used to produce prototype parts and patterns, as well as models to be used for casting the epoxy cutting masters for abrading. This paper will demonstrate how combining new technologies (rapid prototyping, abrading, CNC/EDM) can produce more productive tooling with less lead time.
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