Key Techniques Of Magnetic Field Assisted Micro Electrochemical Machining

With the development of micro/nano technologies, micro parts have been widely used. Micro hard-to-cut parts can be machined with micro electrochemical machining(micro-ECM) technology because of its special machining mechanism. To improve machining precision, magnetic field assisted micro-ECM technology was studied. Three main aspects of the technology (basic theory, electromagnetic generator and magnetic field assisted micro-ECM setup, and machining experiments) were studied.Movement of charged particles in diffusion mode was analyzed with the Fick’s law. Influence of charged particles’ convective flow and convection velocity were analyzed. According to the theory of classic mechanics, influence of charged particles’ trajectory was analyzed with magnetic field. According to the project requirements, an electromagnetic generator (0～0.4T) was developed after selecting of power supply and designing of iron core and excitation coil. Then the magnetic field assisted micro-ECM setup was developed based on the electromagnetic generator.To study the influence of direction (vertical and parallel), intensity (0～0.2T) and space layout (one side and two sides) of magnetic field on precision, a serial of experiments on elastic hard alloy 3J21 and 304 stainless steel were carried out. Influence of machining voltage and pulse width on precision of micro-ECM were carried out under magnetic field. Then micro groove (slot-width 100μum, slot-length 200μm) was machined with and without magnetic field. Based on analyzing structures of workpiece, micro groove was machined via rough machining and finishing machining. A micro cylindrical electrode with 30μm in diameter was used to dissolve most material of the part and left a little margin for finishing machining. Then a micro multi-diameter cylinder electrode with 10μm in diameter was used to machine micro groove. Finally, a micro groove with perfect precision was machined and met the designed requirements.Theoretical analysis and experimental study show that the developed controlable electromagnetic generator can meet the requirements of the magnetic field assisted micro-ECM technology. And the machining accuracy of micro-ECM can be improved with the magnetic field that direction is vertical to machining direction and strength is about 0.1T. With the magnetic field assisted micro-ECM technology, micro hard-to-cut metal parts of many areas (aeronautics and astronautics, ordnance, precision instrument, etc.) can be machined. The study is helpful for the development of micro-ECM.