Fabrication of Micro Halbach Arrays in a Monolithic Ring Magnet by Laser-Assisted Heating Magnetization

Isotropic NdFeB ring magnet (outer diameter: 9.6 mm, inner diameter:7 mm, thickeness:300 µm) was magnetized to form a Halbach array with 40 poles for the rotor in a small and high torque flat motor as follows. The scanning laser beam heats a part of the magnet, weakening the coercivity of the heated part. The heated part is magnetized along the external magnetic field. The direction of the external magnetic flux is switched depending on the angle of the ring magnet to magnetize the heated part. Comparing the surface magnetic flux densities when the same magnet ring was alternately magnetized to 80 poles and magnetized to the Halbach array with 40 poles, the surface magnetic flux density of the Halbach array was 1.7 times that of the alternating magnetism.