The behaviour of REFEL SiC under electrodischarge machining

Electrodischarge machining (EDM) is an important manufacturing technology for machining difficult-to-cut materials and/or shaping complicated contours and profiles with a high material removal rate, low tool wear, and good tolerances. REFEL silicon carbide (SiC) is a ceramic material that is used increasingly as a substitute for metals in modern technology. Machining of this material is very difficult owing to its high hardness and resistance to wear. EDM appears to be the best and perhaps the only nonconventional method for machining SiC parts. Unfortunately, it shows high instability and tendency to arcing, as compared to machining of steel. In this paper, REFEL SiC is machined under 15 different pulse durations. The results show that arcing has the highest level of occurrence among four complete distinct pulses in EDM. The main output parameters (such as stock removal rate and tool wear ratio) do not change appreciably with increasing pulse times and currents. Scanning electron microscope (SEM) pictures show that increasing pulse current (contrary to ED machining of steel) has almost no effect on the integrity of the machined surface. Finite difference analysis of heat transfer on a SiC body shows that the heat is generated mainly near the workpiece surface and close to the plasma channel contact. Results show that an increase in discharge current increases the voltage drop and heat generation within the workpiece body while affecting deeper areas.