(A) study of tool wear in electro discharge machining

Abstract

With electro-discharge machining(EDM) complicated shapes in hard materials can be produced with good accuracy and surface finish. During the process the workpiece is machined to the same shape as the tool electrode. Hence the tool wear is very important with regard to the final shape of workpiece. In this work, a SKD-11 die steel of 3mm thickness was drilled by tool electrode of copper with various corner angle ranging from $30^\circ$ to $150^\circ$ and radius of corner ranging from 0.1mm to 2.0mm. The discharge voltage 50V with a duty cycle of 30\% for current density of 0.16 amperes/$mm^2$ and pulse frequency ranging from 500 c/s to 50000 c/s were used. The result were correlated to give a formula for corner wear in terms of corner angle, radius of corner and pulse frequency. And the empirical function $$W=4.032\,F^{0.1575} \cdot R^{-0.2043} \cdot \theta^{-0.3317}$$ was obtained. In addition, material removal rate, wear ratio, surface finish and overcut were studied under the same machining conditions as those of corner wear except that current density ranging from 0.04 to 0.16 amperes/$mm^2$ were used.