Abstract: To improve flow field in the gap of electrochemical machining(ECM), a series of ECM devices are designed with magnetic circuit embedded inside the clamp lining and permanent magnet inlaid on the cathode sidewall for electrolytic shaping and machining shaped-hole respectively. Finite element analysis (FEA) is applied and experiments are carried out. The configuration with the multi-body gradually changing magnetic circuit is ascertained for electrolytic shaping. The experiments demonstrate that machining results are improved significantly with the shape error of the curved surface less than 0.05 mm, the surface roughness Ra 0.2 μm. When magnetic circuit with N, S alternately arranged is inlaid on cathode the endlong veins on the sidewall of shaped-hole are decreased effectively and the specimen surface roughness is Ra 0.8 μm. The magnetic field is applied in the direction that magnetic flux could perpendicularly cut flow streamline, so that Lorentz force is conducive to the spreading out of the flow beam, thus improving the surface roughness and the accuracy markedly.

Key words: Electrolytic shaped-hole, Flow field, Magnetic field, Electrolytic shaping, electronic differential , linear quadratic regulator (LQR) sliding mode control, robust stability, relative slip rate