EDM performance of TiC/copper-based sintered electrodes

Abstract

This paper presents a study of the effect of titanium carbide (TiC) on the performance of sintered copper-based materials as electrical discharge machining (EDM) electrodes. The aim of this study was to provide a preliminary evaluation of EDM electrodes fabricated by laser-based sintering using rapid prototyping technology (RP). Six batches of titanium carbide with content from 5% to 45% were fabricated by mixing, ball milling, pressing, and liquid phase sintering with copper-tungsten (Cu–W) and copper (Cu), respectively. The performance of the newly formed material is compared with commercial electrodes. The densification of TiC/Cu–W system was improved by the addition of nickel (Ni), as Ni shows good solubility in both Cu and W. The distribution of particle size becomes narrow as the proportion of TiC is increased. A uniform dispersion of small TiC particles in the Cu–W system and a narrow particle size distribution provide the possibility of obtaining dense electrodes. With increasing TiC, the relative density first increased and then decreased, whereas the electrical resistivity first decreased and then increased. EDM electrodes, with the addition of TiC, show good performance in surface finishing. This is an important characteristic as RP-sintered EDM electrodes are expected to be used as finishing electrodes. The surface roughness of most specimens is less than those machined using commercial electrodes. Electrodes with 15% TiC show the highest relative density, lowest electrical resistivity, and good EDM performance, i.e. lowest tool wear ratio (TWR) and highest material removal rate (MRR) at low current, and the best surface finish not only at low current, but also at high current.