Analyzing of Discharge Wave Oscillation Mechanism in Electrical Discharge Machining

In recent years, researches on Electrical Discharge Machining (EDM) plasma mainly focus on the reasons and the characteristics of plasma oscillation and discharge wave oscillation. The mechanism of EDM plasma channel oscillation and discharge wave oscillation, however, has not been explained in detail. This paper chiefly analyzes the geometry change of EDM gap, the diameter change of EDM plasma channel and the electromagnetic field change of EDM plasma. These three factors contribute to the EDM plasma oscillation after affected by one another. On the base of analyzing, a new method of machining by active-oscillation-pulse in EDM has been put forward. The active-oscillation-pulse, which is generated by adding high frequency oscillation component to conventional EDM pulse, can put EDM plasma channel into forced oscillation state. Then the EDM plasma channel will move more frequently and harmful arc discharge will decrease accordingly. Experiment shows that the machining efficiency can be improved remarkably by machining of active-oscillation-pulse.