Achieving high replicability for electrochemical machining via the stamp flushing method in stationary electrolyte

Abstract

Traditional high-speed electrolyte flow for removing bubbles and sludges from the inter-electrode gap during electrochemical machining (ECM) usually results in the non-uniform distribution of temperature, bubbles, and sludges, thus deteriorating machining accuracy. Therefore, ECM performed in stationary electrolyte via an efficient flushing method may solve this problem. For this reason, the previous study proposed the stamp flushing method to squeeze out the bubbles and sludge from the inter-electrode gap by shortening the gap width. However, the effectiveness of the stamp flushing method in achieving high replicability has not been systematically investigated. In the present work, the stamp stroke motion was first optimized to improve the flushing efficiency of the stamp flushing method. To obtain higher stamping velocity and to avoid the damage due to the collision between the tool electrode and workpiece, a cushion mechanism was newly installed on the equipment. Based on the optimized stamp stroke motion, the periodical micropatterns fabricated on the tool electrode surface using wire electrical discharge machining (WEDM) were replicated onto the SK4 workpiece using ECM in stationary electrolyte. The dimensional deviation of the workpiece from the tool electrode after ECM was less than 4 μm in the feed direction and approximately 30 μm in the side direction when the initial width of the frontal gap was 10 μm. Outside the inter-electrode gap, the electrolyte flowing along the axial direction (EFAAD) was supplied to rapidly flush out the bubbles and sludge squeezed out by stamp motion to prevent them from backflowing into the inter-electrode gap during the widening phase of the gap after the stamp motion. Since the EFAAD does not affect the electrolyte in the inter-electrode gap, the ECM remains performed in a stationary electrolyte. High replicability was obtained uniformly over the working surface, which originates from the combined effect of small inter-electrode gap width and uniform distribution of temperature, bubbles, and sludge in stationary electrolyte. This work proves the potential of the proposed stamp-flushing method for manufacturing metal parts with high replicability.