Study on the effect in micro electrical discharge milling using bipolar pulse and deionized water

Abstract

Micro electrical discharge milling (ED-milling) is an effective process for machining of micro structures on hard metals. This method of machining generally uses kerosene or deionized water as a dielectric fluid, both of which are associated with some problems. Kerosene results in considerable electrode wear and deionized water causes electrolytic corrosion in workpiece. Cobalt-bonded tungsten carbide (WC-Co) has been recently used in many industry areas because of its superior mechanical characteristics such as high strength and wear resistance. However, it is difficult to machine WC-Co due to its characteristics. Moreover, it is impossible to make micro-sized figures on WC-Co workpiece using conventional machining methods. In this study, micro ED-milling was carried out using only bipolar pulsed power source to prevent electrolytic corrosion and electrode wear without additional methods. WC-Co was used for the workpiece and micro grooves were machined on the WC-Co workpiece. As a result, optimal pulse condition capable of eliminating electrolytic corrosion is found through the experiments and practical ED-milling was carried out using this condition.