Investigation on saturated magnetization characteristics of anisotropic NdFeB permanent magnet in post-assembly magnetization application

Saturated magnetization of permanent magnets depends on the intensity and direction of the applied pulsed magnetization field. Uneven distribution of magnetization field may results in local unsaturation, especially during the post-assembly magnetization process. Researchers have found that the saturated magnetization field intensity increases with the angle between the magnetization field and the easy axis of anisotropic permanent magnets. When the angle is equal to 90°, the saturated magnetization field tends to be infinite. This paper studies the saturated magnetization characteristics of anisotropic NdFeB. The magnetization experiment platform which can adjust the direction of magnetization field is designed, and the saturated magnetization characteristic curves of sintered NdFeB magnet in fields of different intensity and angle are measured. The experimental results show that the saturated magnetization field intensity increases with the angle between the magnetization field and the easy axis, and when the angle is greater than 70°, magnetization field as high as 10T cannot make the permanent magnet be saturated. The model of the saturated magnetization field along the easy axis and deviate from the easy axis are proposed based on intrinsic coercivity, demagnetization field and an effective field coefficient, which fits the experiment results well. The saturation magnetization criterion of permanent magnetic material is proposed. Combined with the simulation of the intensity and direction of the pulsed magnetization field, we can judge the saturation region of permanent magnetic poles, thus helping us to design the post-assembly magnetization coils.