Abstract
Several insulating ceramics such as Si_3N_4,ZrO_2,SiC could be machined by a Sinking Electrical Discharge Machine using an assisting electrode method. An oxide ceramics of Al_2O_3 is one of the most difficult machining materials for this method. Also the single crystal of Al_2O_3 was recognized as impossible for machining. Recently, we have succeeded to machine these materials with devised assisting electrode material. In this study the effects of the purity of workpiece and thermal conductivity on the machining properties are examined using the noble crystal ceramics such as high purity alumina, sapphire and ruby.
