Fundamental aspects and recent developments in electropolishing

This paper is aimed at reviewing the fundamental aspects and recent developments in electropolishing process. The fundamental theories in the material removal mechanism of electropolishing process are introduced. Since electropolishing is a complicated process including electricity and chemical reaction, it is influenced by many process factors, such as current density, temperature, electrolyte types and workpiece rotation. There is still no available theory which can explain the electropolishing process well, especially when some recent developments were established, the material removal mechanism became more complicated in understanding. However, as the recent developments in the laser machining, additive manufacturing and biomedical device manufacturing, there is a need to use the electropolishing method to post-treat the surface obtained from these methods due to the high industrial requirements. The electropolishing method utilizes the electrochemical reaction between the anodic and cathodic electrodes, when the current is switched on with a DC/AC power supply, to remove the material from the surface of workpiece, hence, the polishing processes of various materials show quite different characteristics on the needed electrolyte types, current densities and so on. Therefore, the electropolishing of various materials is also reviewed in this work. The electropolishing has been not only used for the surface finishing of metal, but also for the passivation, deburring and pattern formation. Finally, a perspective in the development of electropolishing technique is presented to provide a reference for the further research.