Simulation model of debris and bubble movement in electrode jump of electrical discharge machining

Abstract

Electrode jump has a significant influence on the movement of debris and bubble in machining gap and further affects the stability of electrical discharge machining (EDM). Thus, an understanding on the mechanisms of debris and bubble movement in the electrode jump of EDM is important. However, these mechanisms have not been fully understood because it is difficult to observe and simulate the debris and bubble movement in the machining gap. This study proposed a three-dimensional model of flow field with liquid, gas, and solid phases for machining gap in the electrode jump of EDM. Based on this model, the mechanisms of debris and bubble movement in the machining gap in electrode jump were analyzed. Debris and bubble movement in machining gap in electrode jump was observed through experiments. The results showed that the proposed simulation model is feasible. The bubble in the bottom gap moves into the side gap because the flow field of the bottom gap is not centrosymmetric in the electrode jump. The vortexes of EDM oil in the bottom gap are generated during electrode jumping-up, which is the main factor that the debris mixes with the EDM oil. With the proper electrode jump height and speed, much debris and most of the bubbles are excluded from the bottom gap.