Analysis of the machinability of different types of sintered carbides with WEDM in both water and oil baths

Abstract

The unconventional wire electric discharge machining (WEDM) technology represents a vital manufacturing technology in different industrial branches. This technology is essential because of the possibility to machine difficult-to-machine materials such as sintered carbides. For this reason, this study analyses the machinability of sintered carbides WKP23S, WSM33S and WK1 with WEDM in both water and oil baths. We investigated the influence of the machining parameters, namely, pulse off time, gap voltage, discharge current, pulse on time and wire feed, on the cutting speed, surface roughness and defect occurrence. We investigated 9 different roughness parameters, analysed surface morphology with an electron microscope and also analysed cross-sectioned samples. We found out that machining sintered carbides in oil bath yields better results than machining in deionized water. The oil tank prevents the removal of the cobalt binder, but it does not reduce fissure occurrence in any significant way. The lowest Ra value, that is 0.7 mu m, was recorded for the WKP23S sample when machined in oil and Ra 0.9 mu m when the same material was machined in water.