Abstract
Insulating ceramics can be machined by EDM machine with the assisting electrode method. In this method, the formation process of the electrical conductive layer on the workpiece is the most important factor. The EDMed workpiece is covered with cracked carbon that is generated from the dielectric oil during discharge. Machining atmosphere contributes to the formation process of carbonic layer. To clarify the influence of machining atmosphere in assisting electrode method, the effect of temperature, kinetic viscosity and cooling property of dielectric oil was investigated using the designed test machine system. The correlation between properties of the dielectric oil and material removal rate were revealed with the four types of dielectric oil. The optimum kinetic viscosity value was observed in the same compound oils. Elongated long pulse accelerated the material removal rate using some oil that had the good cooling capacity.
