There are two main categories of permanent magnets:

A large category is: metal alloy magnets include neodymium iron boron magnets (Nd2Fe14B), samarium cobalt magnets (SmCo), and aluminum nickel cobalt magnets (ALNiCO).

The two major categories are: Ferrite Permanent Magnets (Ferrite)

1. Neodymium iron boron magnet: It is a magnet with relatively high commercial performance. It is known as magnetic king. It has a high magnetic performance and its BHmax is 10 times higher than ferrite. . Its own machinability is also quite good. High working temperature up to 200 ℃. And its texture is hard, its performance is stable, and it has a good price-performance ratio, so it is widely used. But because of its strong chemical activity, its surface coating needs to be treated. (Such as Zn, Ni plating, electrophoresis, passivation, etc.).

2. Ferrite Magnet: Its main raw materials include BaFe12O19 and SrFe12O19. Manufactured by ceramic technology, the texture is relatively hard and it is a brittle material. Because ferrite magnets have good temperature resistance, low price and moderate performance, they have become widely used permanent magnets.

3. Aluminum-nickel-cobalt magnet: an alloy composed of aluminum, nickel, cobalt, iron, and other trace metal elements. The casting process can be processed into different sizes and shapes with good workability. Cast aluminum-nickel-cobalt permanent magnets have a relatively low reversible temperature coefficient, and the operating temperature can be as high as 600 ° C or more. AlNiCo permanent magnet products are widely used in various instruments and other applications.

4. SmCo is divided into SmCo5 and Sm2Co17 according to the composition. Its development is limited due to its expensive materials. SmCo, as a rare earth permanent magnet, not only has high magnetic energy product (14-28MGOe), reliable coercive force, and good temperature characteristics. Compared with neodymium iron boron magnets, samarium cobalt magnets are more suitable for working in high temperature environments.