Study on the Bubble Dynamics of Single Pulse Discharge in Micro-EDM

Abstract

Micro-EDM (Electrical Discharge Machining) finds extensive applications in the machining of micro-holes and fine features. However, the challenging removal of debris severely limits the machining of micro-holes with large depth-to-diameter ratios. The motion of bubbles generated during electrical discharge machining is considered a key factor influencing debris removal. This study explores the dynamic behavior of individual bubbles produced by single pulse discharge in micro-EDM. High-speed camera was employed to capture the effects of different discharge energies and machining polarity on bubble behavior. Experimental results reveal that machining with negative polarity significantly prolongs the duration of the arc plasma compared to positive polarity machining. Even after the discharge pulse ends, the plasma does not extinguish immediately but persists for a certain duration. Additionally, the final equilibrium diameter of the bubble is positively correlated with the discharge energy.