Machining of Nonconductive Ceramic by Electrical Discharge Machining

The use of nonconductive ceramic materials is increasing rapidly in industrial and engineering applications due to its high hardness, low thermal conductivity, and resistance to oxidation. Machining operations for fabricating structures from nonconductive ceramic materials are difficult and most of the traditional machining techniques are not applicable because of its high brittleness. Electro discharge machining (EDM) technique is applied for processing nonconductive ceramic using assisting electrode. In this technique, pyrolytic carbon layer on the ceramic surface formed by the cracked carbon from the carbonic dielectric plays the key role for continuous EDM. The formation of pyrolytic carbon and its stability depends upon the input power, work piece material, tool electrode material, dielectric substance, polarity, and discharge duration. In this study assisting electrode method and its formation on work piece, some consideration to machining a nonconductive ceramic and effect of various parameters on process performance has been reviewed.