Analysis of Tool Erosion and Circularity in ECDM Using TGRA

Tool erosion and circularity are still a serious challenge in Electrochemical Discharge Machining (ECDM) that limits machining accuracy, tool life and process stability in machining of advanced composite materials. In this study, the effect of tool rotation speed, tool feed rate, ultrasonic vibration amplitude and electrolyte temperature on tungsten carbide tool erosion and circularity during ECDM of Carbon Fiber Reinforced Polymer (CFRP) was analysed. The experiments were planned using Taguchi’s L 18 orthogonal array and machining responses were evaluated through analysis of variance, Scanning Electron Microscopy (SEM), regression analysis and Taguchi-Grey Relational Analysis (TGRA). The results revealed that electrolyte temperature is most influential parameter for both tool erosion and circularity. It highlights the importance of controlling thermal and electrochemical environment during machining. Maximum tool erosion of 1310 µm occurred at 20 µm TVA, 45 °C ET, 600 rpm TR, and 0.5 mm/min TTR, whereas the minimum erosion of 690 µm was obtained at 20 µm TVA, 25 °C ET, 200 rpm TR, and 0.5 mm/min TTR. Hole circularity varied from 0.74 to 0.92 under investigated conditions indicates the sensitivity of hole geometry to machining conditions. SEM examination showed localized tool-tip and edge erosion, surface melting, irregular profile degradation and re-solidified deposits due to combined influence of thermal and electrochemical effects. TGRA provided an optimized parameter combination of 40 µm TVA, 25 °C ET, 200 rpm TR, and 0.5 mm/min TTR, with predicted tool erosion of 625 µm and circularity of 0.96. Compared with Taguchi-based solution, the optimized condition indicates 9.4% reduction in tool erosion and 4.3% improvement in circularity. The results suggest that TGRA-assisted parameter optimization has potential for improving the electrode life and geometrical accuracy in ECDM of CFRP.