Molecular dynamics simulation of material removal process and mechanism of EDM using a two-temperature model

Abstract

Molecular dynamics (MD) simulation has been used to investigate the material removal mechanism in electrical discharge machining (EDM). However, in the previous researches, the simulation model was too small, and the effect of free electrons on the heat conduction has not been considered. To solve the above two problems, in this study, a 2-D sub-micrometer scale simulation with a two-temperature model (TTM) was conducted to simulate the discharge process of EDM, which can consider the effect of both the lattice vibration and free electrons on the heat conduction simultaneously. This 2-D sub-micrometer scale simulation model based on TTM has successfully obtained a sub-micrometer scale discharge crater which was close to the smallest discharge crater reported. Furthermore, the simulation result demonstrates that the pressure generated inside the molten pool serves as one of the removal mechanisms of molten material in the discharge process of EDM. In addition, compared with the monocrystal copper, discharge on the polycrystalline copper can generate much more defect structures and larger denatured layer. Moreover, the smaller the grain size of polycrystalline copper, the more the defect structures and the larger the denatured layer will be.