Deformation of thin graphite electrodes with high aspect ratio during sinking electrical discharge machining

Abstract

In sinking electrical discharge machining (SEDM) use of thin graphite electrodes with high aspect ratio sporadically results in geometrical errors. Mechanical and thermal loads introduced due to jump flushing movements and multiple discharges may exceed critical material properties of graphite. In this paper, deformation effects are modelled by a three step simulation strategy considering discharge distribution, heat evolution and fluid structure interactions (FSI). Mechanical and thermal properties of graphite are characterized with focus on dynamic mechanical thermal analysis (DMA) and implemented into the multiphysics simulation model. Finally, characteristic curves are derived based on simulations in order to avoid critical deformations.