Electric Discharge Machining of Conducting Ceramics - A Review

Abstract

Electrical Discharge machining (EDM) is a nonconventional machining technique, which has been widely used to produce dies and mold. Harder Materials can be machined into complex shapes as long as they conduct electricity. Recent advances in the technologies brought the development of new engineering materials, which are hard to machine with traditional machining processes. Being one of these materials, ceramics possess some unique properties like piezoelectricity and tribological properties which are not found in metal and polymers. EDM is capable of machining these ceramics, given these materials have an adequately high electrical conductivity. Preparing conducting ceramics is pre-requisite for incorporating ceramics in EDM. Different techniques such as compaction, tape casting, extrusion, injection molding and slip casting are used form green ceramic body. These green bodies are subsequently sintered to obtain ceramic parts. Adding conducting elements in the ceramics while processing results in conducting ceramics. These additions increase hardness but fracture toughness of body is compromised. Ceramic parts can also be machined by using assisting electrode and pyrolytic carbon technique. This paper discusses the various methods of shaping conducting ceramics and its machining characteristics for EDM application