It has been established that the formation of an electrically conductive layer on an insulator is a precondition for electrical discharge machining of insulating ceramics by an assisting electrode method. However, the details of the formation mechanism of the electrically conductive layer are not well understood. In this paper, the morphology and components of the machined surface layer are analyzed under different machining conditions of electrode moving speed and voltage threshold for

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... e detection. We describe an idea for the formation mechanism of the electrically conductive layer in the machining of insulating Si3N4 machining by using a machine tool made especially for our experiments. : insulating ceramics, electrical discharge machining, formation mechanism, Si3N4 1,2) 3-5) 4-3-15 1-29-1 112 電気加工学会誌