Electrical Discharge Machining

Abstract

This chapter presents fundamental aspects of the electric discharge machining (EDM) process, a pioneer in advanced machining processes (AMPs). The EDM process relies on the thermal energy delivered to the electrodes (workpiece and tool) for the controlled removal of material, regardless of their hardness or, in general, mechanical properties. The primary source of thermal energy in the EDM process is the discharge plasma generated in the interelectrode gap (IEG). Understandings of discharge plasma formation, and its expansion during the discharging phase is important. Heat transferred to the electrodes plays a dominant role in the overall mechanism of machining in the EDM process. The proportion of heat energy of the plasma channel conducted to the workpiece creates a small cavity on its surface, which is called a crater. The material removal behavior, tool erosion, and surface characteristics of the EDM process are usually appraised through the exploration of a single crater. Keeping this in mind, this chapter tries to incorporate the fundamentals of plasma formation, plasma material interaction, fraction of energy transferred, melt hydrodynamics, and crater formation. Approaches to the modeling of a single crater formation are briefly discussed.