Investigation on the effect of copper tool's grain refinement on material removal rate in EDM processing

Electrical discharge machining (EDM) is a modern machining method which in pace with industrial developments, various studies are aimed at improving this process's parameters including material removal rate. In previous researches, changes in machining tool’s properties and specifications have been investigated as the solution to improve the material removal rate. A novel and efficient process to change material microstructure and properties is equal channel angular pressing (ECAP) that is appropriate method to produce fine grains materials with high strength and adequate properties. In this study, the pure copper material was processed through 4 and 8 passes of ECAP and its effect as a toolfor EDM process, on material removal rate, with different discharge current and pulse ontime was examined. Microstructure of the specimens were analyzed after ECAP operation using electron back scatter diffraction method (EBSD), and the average diameter of grains for specimens were measured using this technique. The results of the experiments indicated that processing the copper tool with ECAP through 4 passes, increases the material removal rate up to 13.2 percent. Moreover, increasing the number of passes of ECAP from 4 to 8 improved the effectiveness of this process on increasing the material removal rate up to 5.5 percent.