A novel micro-EDM method to improve microhole machining performances using ultrasonic circular vibration (UCV) electrode

Abstract

The difficulties in circulating working fluid and expelling discharge debris are major challenges for microhole machining by micro electrical discharge machining (micro-EDM). To solve this issue, a novel micro-EDM method that adopts ultrasonic circular vibration (UCV) electrode was proposed in this study, aiming at effectively improving the microhole machining performances. A piezoelectric device for UCV electrode with 32.85 kHz frequency and 3 μm trajectory radius was developed and its basic principle was analyzed. To better understand the effect of UCV electrode on microhole machining process, the solid-liquid two-phase flow simulation was conducted, and the flow field distribution and discharge debris movement in machining gap were studied. Machining experiments of deep microhole (aspect ratio = 9.4) showed that the UCV electrode can effectively lower the electrode retreat frequency and prevent the debris adhesion at the inner wall. 10 × 10 microhole array machining experiments were also carried out in this study. Results showed that the inlet and outlet of microhole array have better morphologies when using UCV electrode, and the diameter consistency of inlet and outlet were improved by 22% and 2.8% compared with rotating electrode. The advantages of UCV electrode in improve microhle machining performances can be mainly attributed to the significantly enlarged flow velocity of working fluid and enhanced capacity of working fluid to expel debris particles in terms of number and efficiency. Meanwhile, the increased relative velocity between electrode and workpiece is also effective to discontinue the abnormal discharges and achieve stable machining process.