Experimental research on single-pulse discharge crater morphology in SEAM

Abstract

The analysis of craters in electrical discharge machining (EDM) can help improve the understanding of the basic theory and predict the process indexes; thus, the research on craters has been a popular topic in this field. However, a novel low-voltage, high-current EDM technique based on a constant-voltage power supply, namely short electric arc machining (SEAM), is almost completely unexplored. To fill this gap and reveal the basic theory of SEAM, in this work, the influences of the voltage and pulse duration under different polarities on the crater diameter, the width, depth, and thickness of the recast layer, and the bulge height are investigated by single-factor experiments using single-pulse discharge, and the differences between the surfaces and cross-sections of craters are further analyzed. The experimental results demonstrate that as the voltage and pulse duration increase, the discharge channel expands, the energy density of the discharge channel increases, and the crater diameter, the width and depth of the recast layer, and the bulge height all increase. It is also found that negative-polarity machining tends to form large and shallow craters with lower surface roughness, while positive-polarity machining tends to form small and deep craters with higher machining efficiency.