The Effect of Grain Size on Equal Channel Angular Extruded Copper Tools on Electrode Wear in Electro Discharge Machining

Electrical discharge machining (EDM) is one of the most important modern machining processes in today's industry. The tool wear in this operation, due to the nature of the process, reduces the dimensional accuracy of the manufactured parts. Therefore, efforts to reduce tool wear are one of the most important challenges in this operation. For this reason, in this research was carried out using one of the methods of severe deformation, The effect of reducing the size of the copper electrode grains on the wear of spark tools has been studied. At first, high-purity copper bars were placed under the equal channel angular pressing process (ECAP). The average of pure copper grain size was decreased homogeneously from 60.8 to 5.48 micrometer, through the ECAP process. Changing in grain size were determined by using electron backscatter diffraction technique (EBSD). In this study, the effect of factors including pulse on-time and spark current and electrode grain size was examined on the tool erosion. The results showed that, in high material removal rates, the tool wear decreases for 36.8% as compared with the conventional tools. Despite of these results it was clarified that at low material removal rates the wear rate of these two tools do not show vivid differences.