Investigation of the effect of thermal diffusivity coefficient of tool material on electrode-tool wear in the EDM process

Tool wear occurrence causes a variety of difficulties including expensive and inaccurate cutting processes. Therefore, it is imperative to determine which parameter has the most influence on tool erosion rate. Since EDM is basically a thermal process, it is mostly affected by thermo physical properties of tool material. This becomes more important in numerically modeling of EDM process which contributes a better understanding of the wear mechanism. This study aimed to examine the effect of thermal diffusivity on tool erosion rate which has not yet been investigated in detail. Therefore, the experiments were conducted using copper alloy, copper-iron alloy, aluminum alloy and graphite as tools and AISI H13 as workpiece. Additionally, numerical simulation of tool wear was performed using Levenberg–Marquardt technique to gain better understanding of tool wear phenomenon. Results revealed that, increase of thermal diffusivity of tool material decreases tool wear rate. It is observed that in the experiments, performed using tool electrodes with low thermal diffusivity coefficient, the increase of wear rate is significantly intensified with increase of current and pulse on-time. Comparative analysis of the experimental and numerical results indicates that the introduced numerical simulation is capable of estimating tool wear rate with 5% average error, approximately.