Machining electrically conductive ceramics with spark erosion (EDM)

Because of their extreme hardness, ceramic materials and their composites are very popular for mechanical applications that are susceptible to wear and tear due to heavy loads. The other side of the coin is that conventional techniques do not usually suffice to work these materials. Some are even impossible to grind, because oxides deposit on the grinding wheel. For electrically conductive ceramics Electrical Discharge Machining (EDM) or spark erosion offers a solution. But in order to achieve optimum quality, process and material knowledge are indispensable. After all, there is a strong link between material properties and spark behaviour.

Ceramic materials and their composites are known for their extreme hardness (1400-4000 kg/mm2), high rigidity (200-600 GPa), high melting points (1600-3600 °C) and high chemical resistance to corrosion. In addition, certain ceramics (SiC, ZrB2, TiB2, Al2O3, ...) offer the advantage of low specific densities.