Electrical discharge machining processes

Abstract

Electrical discharge machining (EDM) is a removal process which exploits melting and evaporating of workpiece materials caused by pulse discharges which are ignited several thousands to tens of thousands times per second in the small gap between the tool electrode and workpiece. The advantage is that electrically conductive materials can be machined very precisely into complicated shapes independent of their hardness. Hence, EDM is preferably used in die and mold making, aeroengine manufacturing, and micro-hole drilling for ink jet and fuel nozzles, where complicated shapes in hard materials and with high precision have to be machined. This chapter first describes the principle of EDM. Then, the removal mechanism due to single pulse discharge is explained in details from the thermophysical aspects, followed by the clarification of the gap phenomena in consecutive pulse discharges. Thus, the machining characteristics of EDM are understood theoretically based on the fundamental insight into the phenomena.