Research on ECM Finishing Process using Wire Electrode

Abstract In wire electrical discharge machining (WEDM), discharge craters and heat-affected zone impair the surface roughness and generate micro cracks and residual stress. Hence, this study aimed to finish the WEDMed surface by electrochemical machining (ECM) using the same setup, wire electrode and machining fluid used in WEDM. Ultrashort bipolar pulses were used to improve the finishing speed and surface roughness. To realize electrochemical finishing on a WEDM machine, first the influences of the electrolyte concentration on machining characteristics were investigated, and it was found that machining can be performed even if the electrolyte concentration of NaNO3 aqueous solution is diluted to 0.2 wt%. With lower electrolyte concentration, smaller surface roughness was obtained at smaller machining depth. Next, the material of the wire electrode was changed from platinum to brass which is commonly used for WEDM, and the wear rate of the brass wire was investigated. Although the wear rate was 20 times higher than that of platinum, wire breakage did not occur in most of the experiments conducted in the present work. Then, machining was performed with an equal current density for different thicknesses of workpiece, and influences of the workpiece thickness on the process characteristics were investigated.