Magnetic abrasive machining is a newly developed technology for superfinish machining during the latest decade. The magnetic
abrasive materials are put into the space between S-pole and N-pole, which, attracted by the S and N poles and adsorbed onto the workpiece, form a flexible "abrasive material brush" along the direction of the magnetic line of force. Under this condition the workpiece rotates and oscillates simultaneously, thereby the burrs will be abraded and the superficial finish will be greatly improved. In this paper the principle of
magnetic abrasive machining is introduced; the stress analysis of the workpiece in the magnetic field is given. By the experiment of magnetic abrasive machining on inner surface of quenched tool steel (T8A), some technical findings had been achieved. The material removal and the roughness of the machined parts vary with the duration of grinding,
magnetic induction strength and machining clearance. The optimum parameters of magnetic abrasive machining for internal surface are summarized as: magnetic induction strength B=1.0～1.2T;machining clearance Δ=1～3mm;the duration of grinding t=4～5min.