Electrical Discharge/Electrochemical Hybrid Machining Based on the Same Machine and Tool Electrode

Electrical discharge machining (EDM) causes surface defects such as resolidified layer and microcracks, and a finishing process is usually needed to remove these defects. In this paper, a hybrid process was proposed where electrochemical machining (ECM) was performed as a finishing process after EDM using the same tool electrode on the same machine. By using two kinds of disk-type rotary electrodes, rectangular grooves and grooves with convex inner structures were fabricated. Surface topography were investigated by using scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDX), and laser-probe surface profilometer. The material removal mechanism of resolidified layers was clarified. The surface roughness of the rectangular groove was improved from 3.82 μm Ra to 0.86 μm Ra after ECM. Electrode rotation was effective for flushing electrolytic products when fabricating inner structures. As there is no need for exchanging tools and machines, tool alignment error can be prevented and productivity can be improved. Therefore, the proposed EDM/ECM hybrid process contributes to rapid fabrication of microscale products with high surface integrity.