Improvement of ultrasonic cavitation and pumping effect in microhole EDM

Electrical discharge machining (EDM) is frequently employed in micropore machining of difficult-to-cut materials as a result of the contactless characteristics. However, debris produced by electrode discharge ablation of the workpiece tends to accumulate at the bottom of the hole and is difficult to discharge, resulting in abnormal discharge, which reduces processing efficiency and increases electrode loss. These issues can be resolved with the introduction of ultrasonic-assisted technology, but since it is difficult to obviously observe micro phenomena like bubble rupture, fluid movement, and debris movement, there has been little real-situation study on fluid environments. In this study, first, mathematical models of the improvement of ultrasonic-assisted discharge energy and erosion efficiency were developed. Then, the ultrasound-assisted electrical discharge machining (UEDM) process was simulated on the basis of gas–liquid-solid three-phase fluid coupling analysis to investigate the influence law of the ultrasonic cavitation effect and pumping effect on fluid movement and debris movement. Then, the comparative test of EDM and UEDM in machining titanium alloy plate was carried out to explore the impact of ultrasonic-assisted technology on the level of single process parameters, taking the processing time, electrode loss, and hole taper as indicators, respectively. Finally, multi-objective particle swarm optimization (MOPSO) was used to obtain the optimal parameter group of EDM and UEDM, and this parameter group was used for drilling test to examine the effects of ultrasonic-assisted technology on the process parameter level. According to the research, the fluid stability is destroyed by the effects of ultrasonic cavitation and pumping, which also increase the local fluid speed by a hundred times and encourage the discharge of debris, thereby reducing the processing time, lowering electrode loss, lowering hole taper, and improving the surface quality of micropores.