Study of workpiece vibration in powder-suspended dielectric fluid in micro-EDM processes

In micro-EDM (electrical discharge machining), improper removal of debris causes short-circuiting between a tool electrode and a workpiece and in turn, prevents continuous machining process. Therefore, a remarkably longer period of time is required to fabricate a through hole than that would be required when no short-circuiting took place. In order to solve this problem, the dielectric fluid is immersed with graphite nano powders to reduce machining time and improve surface quality due to the less frequent of arcing between the tool electrode and the workpiece. However, excess powders become debris and subsequently deteriorate the efficiency of machining. To fully exploit the effects of the suspended powders, we introduced vibration of the workpiece in order to remove the debris in the small gap between the workpiece and electrode efficiently. The experimental results showed that combination of these techniques improved machining stability, assured continuous machining processes, and significant reduction of the machining time. Reduction of the machining time and the surface roughness of the workpiece after machining were investigated with respect to the powder concentrations when the workpiece was vibrated at 1000 Hz.