Sometimes referred to as spark machining, EDM is a nontraditional method of removing metal by a series of rapidly recurring electrical discharges between an electrode (the cutting tool) and the work piece in the presence of a dielectric field. The ensuing chips are removed by melting and vaporization, and are washed away by the continuously flushing dielectric fluid. Consecutive electrical discharges produce a series of micro-craters on the work piece until the desired shape is achieved.
The EDM process is most widely used by the mold-making tool and die industries, but is becoming a common method of making prototype and production parts, especially in the aerospace and electronics industries in which production quantities are relatively low.