Influence of electrode material in micro-EDM drilling of stainless steel and tungsten carbide

The aim of this work is to analyze the influence of electrode material in micro-electro-discharge machining (EDM) drilling of stainless steel and tungsten carbide metal plates. Brass and tungsten carbide electrodes were selected based on their different electrical and thermal properties. The experimental campaign was based on the execution of a large number of micro-holes carried out by varying some process parameters, namely the peak current, voltage, and frequency. The tool wear ratio and material removal rate were assumed as process performance indexes, while the diametral overcut and taper rate were considered as geometric indexes. The analysis of variance (ANOVA) was applied on the results coming out from the experiments. Moreover, an overall Process Index based on both process parameters and electrode material properties was proposed. This index fits, with a good correlation level, all the process performance and geometric indicators for both the considered workpiece materials. A comparison between the performance measured using stainless steel and tungsten carbide workpieces was also carried out. The results of this experimental research showed that electrical resistivity, thermal conductivity, and melting point of both electrode and workpiece materials have a significant effect on the process and geometric performance.