Study on improving the surface roughness of multi-stage internal cone hole by rotating magnetic field assisted electrochemical machining

In order to further improve the surface quality of electrochemical machining multi-stage internal cone hole parts, the method of rotating magnetic field–assisted electrochemical machining is proposed in this paper, a new cathode structure which inlaid Nd-Fe-B permanent magnet on the side wall was designed, and the simulation study on the effect of the magnetic field on the uniformity of the flow field in the machining gap was carried out. Under the conditions of 7 V, 5 mm/min cathode feed speed, 0.15 r/s cathode rotation speed, composition electrolyte 5%NaCl+15%NaNO₃+5%NaClO₃, electrolyte temperature 30°C, and inlet pressure 1.6 MPa, a comparative experiment of electrochemical machining with and without a rotating magnetic field was conducted. The results show that under the same machining parameters, when there is no magnetic field, the surface roughness of the workpiece is Ra0.847μm, while when a rotating magnetic field is added, the surface roughness of the workpiece is Ra0.437μm. The workpiece surface quality of the multi-stage internal cone hole is improved by 48.41%. It indicates that the rotating magnetic field can change the flow direction of the electrolyte and improve the uniformity of the flow field in the machining gap. Adding a rotating magnetic field is an effective method to improving the surface quality of electrochemical machining.