Stray-corrosion-free ECM with electrolyte absorbed in a porous solid ball for dimple texturing on finished workpiece surfaces

Abstract

Dimple textures are widely used on the finished workpiece surface. For example, shallow grooves with a depth of micrometers are typically used as oil pockets on sliding surfaces, and dimple textures are also used on metal workpiece surfaces to mark product logos or product numbers. Electrochemical machining (ECM) is commonly used because it does not produce heat-affected layers, residual stress, or microcrack. However, stray-corrosion of ECM decreases the surface quality of the finished workpiece and is challenging to solve. In this study, to process dimple textures on a finished workpiece surface, a new ECM method was employed, with a porous solid ball serving as the electrolyte absorption material. During processing, the electrolyte distribution is limited by the porous solid as no electrolysis occurs in the unintended processed area. Hence, it leads to a stray-corrosion-free process. Before processing, the proposed ECM method was analyzed with a simulation to investigate the electric potential, current density distribution, and processed result. Finally, combined with the control of the power supply switching and the relative movement between the tool electrode and workpiece, shallow dimples with different depths, lengths, and patterns were obtained.