Recast layer removal of WEDMed surface by wire electrochemical finishing

Abstract

To eliminate the recast layer on the surface machined by multi-pass wire electrical discharge machining (WEDM), hence improving the surface integrity, the present paper proposed and investigated a new combined machining process of performing wire electrochemical machining (WECM) after multi-pass WEDM on the same machine tool by utilizing the slight conductivity of the compound working fluid. A theoretical model based on the electric double layer and Faraday’s law of electrolysis was established to calculate the wire feed rate for WECM finishing. Due to the exclusive film protection of the compound working fluid, the theoretical model was modified according to the experimental results under different electrolyte concentrations. Afterward, the optimized model was applied to guide the experiments of the combined process. An electrolyte concentration of 1:5 was used to facilitate the electrochemical reaction. The experimental results showed that the remaining recast layer after multi-pass WEDM could be completely removed at a wire feed rate of 10 µm/s, and a fine surface finish could be obtained. In addition, the surface roughness of the machined part was improved from 1.458 µm Ra to 0.683 µm Ra.