A novel EDM method using longitudinal-torsional ultrasonic vibration (LTV) electrodes to improve machining performance for micro-holes

Abstract

This study proposes a new EDM method using longitudinal-torsional ultrasonic vibration (LTV) electrodes for micro-hole machining to address the problems of debris removal and difficult working fluid exchange in micro-hole processing, which can enhance the micro-hole machining performance. A 38.9 kHz ultrasonic vibration transducer is developed for LTV electrodes, and the fluid distribution in the micro-holes gap is simulated when LTV electrodes were used to process micro-hole. The effect of ultrasonic amplitude on flow rate and debris removal efficiency is discussed. A study is conducted to analyze the morphogenesis of the electrode extremity and the micro-hole inlet/outlet at different amplitudes. This study finds that applying appropriate ultrasonic amplitude (2–4μm longitudinal amplitude, 0.2–0.35μm torsional amplitude) to the electrode effectively reduces the electrode tip and corner wear and the flanging burr of the micro-hole inlet/outlet. Compared EDM micro-hole machining with the rotating electrode only, the material removal rate (MRR) is increased by nearly two times with the simultaneous application of 4 μm longitudinal ultrasonic amplitude and 0.35μm torsional ultrasonic amplitude to the electrode, and reduction of electrode wear and micro-hole taper by approximately 60% and 80% respectively.