Surface integrity assessment under ultrasonic vibration-assisted rotary tool synergy in electrochemical discharge machining

This study examines surface integrity in electrochemical discharge machining (ECDM) of glass under the synergistic action of ultrasonic vibration and tool rotation. The experimental setup features a precision-runout coupling between the ultrasonic horn and rotary motor, ensuring stable energy transfer. We quantitatively analyzed the roles of ultrasonic vibration, tool rotation, inter-electrode gap (IEG), and auxiliary electrode geometry. High ultrasonic amplitude and a wider IEG improved surface quality by enhancing cavitation and spark uniformity, whereas high tool rotation increased entrance hole overcut and microcracking. SEM and EDX analyses, along with Ra values, indicate that low ultrasonic vibration and a narrow IEG produce rough, uneven, and redeposited surfaces. Rectangular auxiliary electrodes provide better machining quality than circular electrodes. The findings demonstrate that the combined effect of ultrasonic vibration-assisted rotary tool in the ECDM process dictates the trade-off between depth of penetration, hole overcut, and surface finish in glass microfabrication.