Magnetohydrodynamics Study on the Mechanism of Improving the Efficiency of Magnetic Field-Assisted Electrochemical Micro-Machining

High-precision surface of 201 stainless steel obtained by electrochemical micro-machining without or with magnetic field-assisted was studied by combining experiments and simulations. The results demonstrated that the surface roughness of the samples was reduced to 0.40 μm after 18 min electrochemical micro-machining. Besides, the introduction of the magnetic field further improved the surface accuracy and reduced it to 0.20 μm. At the same machining time, the magnetic field-assisted electrochemical micro-machining provided lower surface roughness, which indicated that the magnetic field had a favorable impact on the improvement of machining efficiency. Additionally, the distribution characteristics of magnetic induction lines in the machining gap were also discussed. When the magnetic induction lines were approximately parallel to the anode surface and perpendicular to the electric field, the processing efficiency was further improved. The simulation results showed that the current density on the anode surface and the mass transfer rate of the electrolyte were enhanced by the existence of the magnetic field, which accelerated the electrochemical reaction behavior. The external permanent magnet contributed magnetohydrodynamic force during electrochemical micro-machining promoting the occurrence of magnetohydrodynamic convection. Consequently, the charge and the mass transfer in electrolyte was expedited, indicating the improvement of processing efficiency.