Characteristics of ECM polishing influenced by workpiece corner feature and electrolyte flow

Abstract

When polishing workpiece with inner corner feature using electrochemical machining (ECM) process, the surface quality at corner area is much poorer than that at other areas, and the surfaces of upstream area and of downstream area are much different. In this paper, the characteristics of this corner area phenomenon was investigated. Since the current density has a great influence on the surface roughness in ECM process, understanding the current density distribution on workpiece surface helps to analyze the corner area phenomenon and clarify process characteristics. Current density distribution considering the influences of several factors such as corner shape and inter electrodes gap (IEG), bubbles and electrolyte flow, were obtained with simulation and verified by experiments. ECM polishing with different fillet radius of the corner under different current densities were carried out. The observation experiments of machining by-products flowing with electrolyte flushing between machining gap, as well as the measurement of current densities at different areas, were conducted. The experimental results showed accordance with the simulation results. It was found the corner shape greatly influence the current density thus the surface roughness at the corner area, while the transport and accumulation of gas bubbles with electrolyte flow is one of the main reasons for the difference of surface roughness between the upstream area and the downstream area.