Analysis of Material Removal Rate and Electrode Wear in Sinking EDM Roughing Strategies using Different Graphite Grades

For industrial applications graphite is becoming more and more the electrode material of choice for sinking EDM. Especially f or roughing graphite offers great advantages compared to copper electrodes. Optimized parameters lead to a very low tool wear rate combined with a high material removal rate. As a result the number of tool electrodes for a certain EDM task can be reduced significantly leadin g to very short machining time. A satisfactory explanation for these benefits could not be found until now. Therefore the specific wear behavior and material removal rate is investigated in detail in this paper and linked to the physical characteristics of the graphite material. In total 5 different kinds of graphite were chosen with significantly different physical characteristics concerning their specific electric resistance, thermal conductivity and grain size. The performance of each grade was evaluated in terms of material removal rate and tool wear for roughing.