Reduction of stray currents in counter-rotating electrochemical machining by using a flexible auxiliary electrode mechanism

Counter-rotating electrochemical machining (CRECM) is a new ECM technique which can be used to fabricate convex structures on thin-walled revolving parts. During the CRECM process, the non-machined top surface of the convex structure inevitably suffers from stray current attack, resulting in poor machining quality. To reduce the stray currents in CRECM, a flexible auxiliary electrode mechanism has been developed. A positive potential difference is applied between the auxiliary electrode and the anode workpiece. The electric field distribution and the simulated convex profiles show that the stray current density can be reduced effectively by using an auxiliary electrode. The magnitudes of the stray current densities on the non-machined area decrease with increasing potential difference. A suitable positive potential difference of 10 V is able to completely eliminate the stray currents from the entire non-machined surface of the convex structure. Experiments have also been conducted to verify the proposed method. It was confirmed that the stray corrosion on the convex surface is significantly reduced and the machining quality is remarkably improved by using a flexible auxiliary electrode mechanism.