Analysis of the electrochemical behaviors of WC-Co alloy for micro ECM

Abstract

Micro electrochemical machining (ECM) of tungsten carbide with cobalt binder (WC-Co) was studied using ultrashort pulses. In ECM, the machining characteristics were investigated according to machining conditions such as electrolyte, workpiece potential, and applied voltage pulse. Using a mixture of sulfuric acid and nitric acid, microstructures with a sharp edge and good surface quality were machined on tungsten carbide alloy. The potentials of workpiece electrode and tool electrode were determined by considering the machining rate, machining stability, and surface quality of products. With the negative potential of the workpiece electrode, oxide formation was successfully prevented and shape with good surface quality in the range from R-a 0.069 mu m to 0.075 mu m were obtained by electrochemical machining. Moreover, the performance of ECM, which includes machining gap, tapering, surface roughness, and machining time, without tool wear was compared with that of electrical discharge machining (EDM). Microstructures of WC-Co with a sharp edge and good surface quality were obtained by electrochemical milling and electrochemical drilling. Micro electrochemical turning was also introduced to fabricate micro shafts. (C) 2012 Elsevier B.V. All rights reserved.