Experimental investigation on simultaneous machining of EDM and ECM of Ti6Al4V with different abrasive materials and particle sizes

Abstract In view of the difficult machining characteristics of titanium alloys and the limitations of EDM/ECM serial machining, a study of parallel machining of EDM and ECM with the aid of abrasive particles was carried out using a low conductivity NaNO3 salt solution as the working medium. Firstly, the influences of the electrical conductivity of working medium, abrasive material and abrasive particle size on material removal rate, electrode loss rate, surface roughness and surface microstructure were analyzed. Then, the material removal rate, electrode loss rate and surface roughness were taken as evaluation indexes, and the multi-process objectives were transformed into a single evaluation index by orthogonal test and grey correlation analysis. The optimal combination of the main process parameters including peak current, pulse width, abrasive particle concentration and gap voltage was obtained, and the experimental verification was carried out. The results show that under the same electrical parameters and machining conditions, the comprehensive machining effect is better when the conductivity of working medium is 300 µS/cm. Compared with Cu and Al abrasives, although SiC abrasives have the lowest material removal rate, the electrode loss rate and surface roughness are the smallest; according to the analysis of multi-objective grey correlation degree, the optimal combination of process parameters for EDM and ECM parallel machining assisted by SiC abrasive particles with particle size of 50 µm is as follows: peak current 1.5 A, pulse width 15 µs, abrasive concentration 5 g/L and gap voltage 40 V. Compared with other parameter combinations, the electrode loss rate, surface roughness and surface morphology are improved obviously under this parameter combination.