Investigation of Liquid Electrode for Micro-electro-discharge Machining

Abstract

Liquid electrode for Micro-electro-discharge machining is proposed and developed to address a variety of problems associated with electrode wear. An electrically conductive liquid metal alloy, Galinstan, is supplied through a metallic capillary nozzle such that the surface of the liquid is projected over the flat bottom of the nozzle. A discharge pulse generator is connected between the liquid (through the nozzle) and the workpiece. When the nozzle tip (covered by the liquid electrode) approaches the workpiece surface, it initiates discharge pulses when the gap meets the breakdown condition so that the generated pulses can thermally remove the material. During the machining process, a liquid electrode is continuously supplied to a metallic micro capillary nozzle to eliminate the impact of liquid consumption on the removal process. Experiments show that Galinstan, can be used as the electrode material to create discharge pulses and perform microscale removal on the samples. Controlled discharge generation and scanning-mode arbitrary etching are experimentally demonstrated using the Galinstan electrodes. It is also shown that a Parylene C coating is effective for protecting the nozzle from discharging.