NdFeB magnets include sintered NdFeB magnets and bonded NdFeB magnets. Sintered NdFeB magnets are usually designed as arc-shaped tile magnets or rectangular magnetic strips, and are installed in an alternating sequence of S/N poles. This structure allows NdFeB magnets to provide a stable and strong magnetic field. Ring motor magnets are generally bonded neodymium magnets, and ring motor magnets usually require multi-pole magnetization. Although the magnetic force of NdFeB magnets is very strong, eddy current loss is a problem that must be considered when choosing NdFeB magnets. The working temperature of NdFeB magnets is usually between 80 degree and 230 degree depending on the magnetic grade. (For the operating temperature of NdFeB magnets, please refer to the article on the effect of temperature on NdFeB magnets.) Once the high temperature caused by eddy current loss exceeds the working temperature of NdFeB magnets, it will cause irreversible demagnetization.
2. Samarium Cobalt Magnet
3. AlNiCo magnets
Alnico magnets are less magnetic than rare earth magnets and are therefore rarely used in motors. Under some special conditions, the motor needs to work above 350 degree . At this time, the samarium cobalt magnet with a temperature resistance of 350 degree is powerless. We can only choose alnico magnets. The maximum working temperature of alnico magnets is usually 550 Celsius.
4. Permanent magnet ferrite magnet