Flow field research on electrochemical machining with gas film insulation

Abstract

Electrochemical machining (ECM) is an efficient method for fabricating crucial components of aircraft engines, such as integral blisks and diffusers. This paper proposes a new method for decreasing the stray corrosion in trepanning ECM, in which air is supplied around the machined workpiece to remove stray electrolyte. Specifically, compressed air was blown into the cathode and through the workpiece in a forward flow mode, thereby forming a gas film on the machined surface. Simulations were performed using the ANSYS software to determine the distributions of compressed air and electrolyte in the machined area. The simulation results demonstrated a uniform air–electrolyte distribution and a stable flow field under the optimal parameters. Experiments were conducted to verify these results, and the gas film was found to exert an obvious influence on reducing the taper angle and improving the surface quality of the workpiece. Severe corrosion of the workpiece occurred in the absence of air flow, whereas the stray corrosion was significantly reduced when air was supplied through the cathode. Upon increasing the feed rate from 0.5 to 1.5 mm/min, the taper angle decreased from −0.012° to −0.003° and the surface roughness decreased from Ra 0.841 μm to Ra 0.266 μm, whereas the optimal values for the samples obtained without the gas film were 0.096° and Ra 0.993 μm at the feed rate limit of 1.0 mm/min.