Study on characteristics of EDM using pulse power supply with active high-frequency oscillation

Abstract

One main disadvantage of electrical discharge machining (EDM) is its low machining efficiency, which limits the further application of EDM. Comparing the spark discharge waveform and the arc discharge waveform under the transistor pulse power supply, it can be found that a high-frequency oscillation component is presented in the spark discharge waveform during the discharge, while the high-frequency oscillation component does not exist in the arc discharge waveform. Inspired by this phenomenon, a new pulse power supply with active high-frequency oscillation was developed in this study, which can provide rectangle pulse discharge current with high-frequency oscillation component. Experimental results show that compared with the traditional transistor type pulse power supply that only generates rectangle discharge current, the pulse power supply with active high-frequency oscillation component can improve the machining efficiency effectively and reduce the tool electrode wear without influencing the surface roughness. Further, the influences of the oscillation frequency and the oscillation amplitude of on the machining characteristics were investigated. In addition, under active high- frequency oscillation current, by the high-speed observation of the arc plasma, the measurement of the discharge craters and the statistics analysis of the effective discharge rate, the influence mechanism of active high-frequency oscillation current on the material removal of EDM was discussed.