Realization of high-precision electrochemical machining by active use of hydrogen bubbles generated in non-machining area

Abstract

Electrochemical machining (ECM) is an effective technique for producing both macroscopic and microscopic components of industrial devices. However, achieving high precision in ECM necessitates overcoming the challenge of stray corrosion. This study introduces a novel approach for enhancing the precision of ECM by employing bipolar pulses and an auxiliary electrode to significantly reduce stray corrosion. The innovative strategy utilizes the substantial production of hydrogen bubbles at the cathode surface to localize the electrolytic current to the intended machining area. During the negative pulse phase, both the workpiece and the tool act as cathodes, promoting intensive hydrogen bubble formation in regions not designated for machining, while minimizing bubble generation in the target area. Consequently, these bubbles decrease the stray current traversing the untargeted area during the positive pulse phase. This study reveals the underlying machining principles and the circuitry designed to facilitate this method. Through simulations and experimental validation. Simulations and experiments were performed to demonstrate the effectiveness of the proposed method. The results reveal a significant reduction in stray current in non-machining areas due to hydrogen bubble formation. When compared to conventional ECM employing unipolar pulses, the bipolar pulsed ECM produces holes with superior precision, characterized by reduced overcut and increased depth. Additionally, the surface roughness (Ra) at the base of the machined groove is enhanced by approximately 1.3 times.