Slotted electrodes for the improvement of machining performances in EDM drilling

In electrical discharge machining (EDM), poor debris removal may occur under certain conditions. This leads to debris accumulation and degrades machining efficiency. In this study, the rotation and retracting movements of slotted electrodes were coordinated during EDM to realize a pumping effect for expelling debris in the gap between the electrodes and workpieces. The study compared the performance of different slotted electrodes with that of a regular cylindrical (RC) electrode. Moreover, a computational fluid dynamics module was adopted to simulate the effects of the RC and slotted electrodes on debris removal capability in EDM under different conditions. The experimental results demonstrated that among all slotted electrodes, the deep slotted electrode engendered the most-favorable debris removal capability. The deep slotted electrode saved machining time by shortening the electrode jump time or even obviating electrode jumping. This increased the material removal rates by 120%–153% during EDM drilling.