Influence of Tool Size on Machining Characteristics of Micro-EDM

Abstract Electrical discharge machining (EDM) is an alternative processing method of conductive materials. Stray capacitance exists between the electric feeders, between the tool electrode holder and work table, between the tool electrode and workpiece. The energy stored in the stray capacitance cannot be neglected similarly to that in macro EDM due to the low discharge energy. It is necessary to research the capacitive effect to better apply micro-EDM. In this study, the influence of the tool electrode scale on micro-EDM performances was analyzed from the perspective of capacitive effect. The stray capacitance was calculated by using the charging waveforms. Experimental results elucidate that material removal rate (MRR), tool wear rate (TWR), and diametrical overcut (DOC) increased with the enlargement of tool size. When the tool diameter was greater than 500 μm, the rate of increase in MRR was apparently higher than that of TWR, and the relative tool wear ratio (RTWR) exhibited a downward trend. This study benefits to better understand the capacitive effect and provides a reference for building the machining performance prediction model of micro-EDM.