Effects of flushing on electro-discharge machined surfaces

Abstract

Although the influence of flushing on the efficiency and stability of machining conditions in EDM has been extensively investigated, including the effects of the flushing configuration on the wear of the tool and the profile of the workpiece, little has been reported concerning the effects of flushing on the integrity of the electro-discharge machined (EDMed) surfaces. This paper presents the effects of flushing rates on the types and distribution of recast layers in commercially pure iron, 0.5% C steel and AISI 01 tool steel after EDM. There exists an optimal dielectric flushing rate where cracks and average thickness of the recast layer are at a minimum for all three materials. The trends for the crack density and recast thickness are similar, being higher at flushing rates below and above a basically similar optimum rate. The distributions of the crack density at the sides, bottoms and corners of the machined cavities under different flushing conditions are presented. Based on the results obtained, the effects of the quenching property and debris removal ability of the dielectric flow conditions on the recast layers of the three types of EDMed specimens are discussed.