Electric discharge machining of non-circular through-holes: material removal and tool wear analysis

EDM die-sinking is one of the important processes used in the manufacturing of dies and molds. Various circular and non-circular shapes are produced through this process. However, the EDM process has two major limitations such as the material removal rate is comparatively very low as compared to other processes and the tool wear rate during EDM is also high as a result of which the dimensional accuracy of the machined feature is compromised. Researchers are being continuously working on the process to improve the materials removal rate and reduce the tool wear rate. In the current investigation, the performance of EDM has been evaluated improved by the introducing new tool designs. Non-circular shaped holes that are extensively used in the mold industry have been selected as the machining profiles. The performance measures are evaluated against three machining responses such as material removal rate and tool wear in two different perspectives. The tool designs having varying cross-sectional area are used to produce non-circular holes of three shapes (square, triangle, and hexagon) in AISI D2 steel. The machining results corresponding to the tools introduced in this research are compared with the results obtained through the use of conventional tool (the tool having uniform cross-sectional area along the length of tool). The results revealed that the material removal rate of EDM can be significantly improved through the use of tool designs employed in this research. Likewise, the machining accuracies can also be improved since the tool wear was also less than the wear caused in conventional tool design.