Accretion behavior and debris flow along interelectrode gap in μED-milling process

Abstract

In microelectrodischarge milling (μED-milling) process, material removal occurs in the form of debris and these particles are predominantly spherical in shape with size varying from few nanometers to micrometers. The behavior of the debris particles in μED-milling is not well discussed in the literature, and this study will provide useful insight into the debris movement and its accretion on machining surfaces. Debris in its molten or cooled state will cause major issues in the μED-milling process such as secondary discharge and redeposition. Its presence at one location in large number gives rise to secondary discharge causing a disturbance in sparking, and its movement may affect the geometry of channel due to redeposition. The necessary drive for debris movement along the gap is provided by tool rotation. The experimental investigation of debris movement with dielectric at a gap of few micrometers is practically difficult due to complex phenomenon of the process. Thus, the present objective is focused to investigate the movement of debris and dielectric in the gap through simulation with consideration for fluid debris interaction and subsequent deposition. The effect of debris size, the position of injection, and the tool speed on the accretion of particles on the surface are analyzed by ANSYS Fluent. The trajectory of the particles, distance traveled, and accretion rate are calculated using discrete phase modeling. The 2D simulation results of accretion are compared with experimental surface micrographs.