In electrical discharge machining (EDM) process, the reduction of electrode wear is very important for high accuracy machining. It is reported that low electrode wear EDM can be achieved by the adhesions of workpiece material and heat resolved carbon from machining fluid to the electrode end surface, because of the protection effect of the latter which has large heat resistivity. Under a proper condition, even no electrode wear EDM is possible. Such adhesion phenomenon, however, is observed only on the condition that the pluse duration is relatively large. That is, it never occurs on the small pulse duration such as finishing condition. Therefore, no electrode wear EDM under finishing condition is impossible so far and the electrode wear in finishing EDM is practically allowed to be inevitable. It is reported that the heat resolved carbon from machining fluid adhering to the electrode end surface is turbostratic carbon. It has the chemical structure in which hexagonal lattice plane laminates irregularly, different from graphite structure. From these results, it is considered that no electrode wear EDM might be attained by using turbostratic carbon electrode under finishing condition.
In this study, EDM characteristics of a newly developed CVD-carbon electrode are experimentally investigated for higher performance EDM. Experimental analysis made it clear that low electrode wear EDM is possible by using CVD-carbon electrode even under finishing condition, since the heat resolved carbon from machining fluid has a stronger tendency to adhere to the end surface of CVD-carbon electrode than that of graphite one.
