Characteristics and function of vapour gaseous envelope fluctuation in plasma electrolytic polishing

Plasma electrolytic polishing (PEP) is an innovative technology used in polishing metal workpiece surfaces, especially for complex workpieces. To date, the function of the vapour gaseous envelope (VGE) fluctuation in electrolyte plasma polishing remains indistinct, leading to differences in understanding of the smoothing mechanism of PEP. This paper primarily aims to reveal the evolution process of VGE with voltage change and the function mechanism in the PEP. Accordingly, the polishing efficiency, change of electrolyte properties, and electrical signal data of stainless steel are experimentally investigated under different voltages. The results show that the evolution of VGE with the increase of voltage can be divided into four stages: microbubble stage, formation stage, fluctuation stage and stable stage. Corresponding to the fluctuation stage of VGE, the surface roughness of the workpiece can be reduced from the original Ra 0.7 mu m to 0.2 mu m in the voltage range of 200-400 V. It can be concluded that the fluctuation of VGE is the key to the effect of PEP, the fluctuation of the VGE makes the electrolyte constantly contact and separate from the workpiece surface. The electrochemical reaction occurs during contact, and plasma discharge channels are formed during separation. Additionally, the electrochemical reaction is the main cause of surface material removal, and the positive effect of plasma discharge is to produce a shock wave to remove electrolytic products on the surface of the workpiece.

Automated summary

This study investigates the evolution process and function mechanism of the vapour gaseous envelope (VGE) with voltage change in plasma electrolytic polishing (PEP). The results indicate that the fluctuation of VGE is the key to the effect of PEP, as it enables electrolyte to constantly contact and separate from the workpiece surface, leading to electrochemical reactions and plasma discharge for polishing.