The magnetization direction (magnetic field polarity direction) must be strongly correlated with the irregular structure and function; otherwise, the efficiency will be significantly reduced:
Arc-shaped magnets: Often use "radial magnetization" (magnetic field radiates from the inner circle to the outer circle), matching the rotating magnetic field requirements of the motor rotor (e.g., in permanent magnet synchronous motors, the radial magnetic field of the arc-shaped magnet maximizes torque output); if axial magnetization is mistakenly chosen, the magnetic field utilization will decrease by more than 40%.
U-shaped magnets: Usually use "opposite-pole magnetization" (the two arms are N/S poles respectively), forming a closed magnetic field loop, suitable for scenarios requiring a strong magnetic field in the gap (e.g., magnetic clamps, where the magnetic field strength at the U-shaped opening can be 2-3 times that of the center).
Porous irregular magnets: The magnetization direction must avoid the holes (holes cause magnetic field line distortion), and magnetization is usually applied axially or perpendicular to the hole axis to ensure magnetic field uniformity (e.g., porous positioning magnets in sensors).
