EDM PERFORMANCE ANALYSIS FOR ELECTRODEPOSITED Cr-/Ni-/SiC-COATED Cu ELECTRODE ON WASPALOY

Virgin copper, graphite, brass, tungsten carbide, silver tungsten, and copper tungsten electrode materials had been commonly used in Electrical Discharge Machining (EDM) Ni-based superalloys. Among the various electrode material properties, virgin copper alloy is used widely in machining superalloy series due to its high thermal conductivity. High electrode wear rate has been found in EDM owing to its low wear resistance in the copper electrode. In order to increase the wear resistance of virgin copper electrode (Cu), the chromium-coated Cu (Cr–Cu) electrode, Nickel-coated Cu (Ni–Cu) electrode, and the silicon carbide-coated Cu (SiC–Cu) electrode performance on Electrode Wear Rate (EWR) and Residual Stress (RS) of Waspaloy have been investigated using EDM with varying the pulse duration, peak current and concentration of silicon. The SiC–Cu electrodes have improved the 0.838 times hardening depth, 2.68 times coefficient of friction, 2 times hardness in electrode and 3 times Waspaloy machined surface hardness and 4.333 times scratch depth compared with virgin Cu electrode. The XRD results with SiC–Cu electrodes have shown a high Ni phase and TiC phase formation in the machined surface of Waspaloy for increasing the hardness. The 5 times EWR and 4 times RS have reduced with increasing the pulse duration. The 0.7 times EWR and 0.5 times RS reduced with increasing peak current. The 2 times EWR and 3 times RS reduced with increasing concentration of silicon powder in EDM oil. Overall analysis found that the SiC–Cu electrode showed a superior performance over the Cu, Cr–Cu and Ni–Cu.