1995 / Solid Freeform Fabrication Proceedings
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Author Brent E. Stucker, Walter L. Bradley, Somchin (Jiab) Norasetthekul, Phillip T. Eubank, Texas A and M University
Source Solid Freeform Fabrication Proceedings, 1995, pp 278-286
Abstract Electrical discharge machining (EDM) has become common place in the tool and die industry as an alternative to conventional machining and now accounts for 2% of worldwide machining, with a substantially greater concentration of use in the tool making industry. EDM has the advantage of allowing tool steel billets to be heat treated to full hardness before the cavity is produced, obviating the need for heat treatment after machining--a step that often results in the loss of dimensional accuracy due to distortion in the quenching from high temperature austenite to martensite at room temperature. Any material with less than 1 ohm-m of electrical resistivity, regardless of hardness, can be machined using EDM. EDM also allows the convenient production of complex shapes in the tool cavity, as complex topographies can often be more easily machined on the electrode than inside a cavity. Even certain simple shapes such as rectangular or square cavities are far easier to produce using EDM than conventional machining. EDM machining, however, is precluded from many market niches by the relatively high cost of electrode production In visiting with approximately sixty representatives from the EDM industry, we have learned that the cost of electrode fabrication is often greater than 50%, and sometimes as great as 80%, of the total cost of fabricating a die using EDM. The wear ratio of the two most commonly used electrode materials, graphite and copper, requires the use of multiple electrodes in the production of each cavity, because the electrode wears away and loses its initial shape too quickly. Thus, the replacement of graphite and copper electrodes with electrodes made of materials which are more resistant to electric spark erosion would significantly improve the cost effectiveness of EDM tool production. (Auth abstract) [References: 23]
Solid Freeform Fabrication Proceedings can be obtained from: The Solid Freeform Fabrication Symposium
or contact:
The University of Texas at Austin
Laboratory for Freeform Fabrication / Texas Materials Institute
Mechanical Engineering Dept.
c/o The Solid Freeform Fabrication Symposium
MC C2200
Austin, TX 78712-1063 USA
512-471-3026; 512-471-7681 FX; Email: sffsymp@uts.cc.utexas.edu