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Precautions for the Application of Permanent Magnet Materials

The permanent magnet material works in the second quadrant demagnetization part of the hysteresis loop. Permanent magnetism is a property of what kind of magnetic materials. However, as an important basic magnetic functional material, permanent magnetic materials have a very broad application field. 

Pay attention to the following matters when applying permanent magnet materials:

1. The actual magnetic properties of permanent magnet materials are related to the specific manufacturing process of the manufacturer. And there is often a certain deviation between its value and the data specified by the standard. There will be certain magnetic performance differences between different factories or different batch numbers of the same brand of permanent magnet materials. For the shape and size of the permanent magnet actually used in the motor, there will be a certain difference between its magnetic performance and the standard data. In addition, the capacity of the magnetizer and the magnetizing method will affect the uniformity of the magnetization state of the permanent magnet and affect the magnetic performance.

2. The magnetic properties of permanent magnet materials are not only related to alloy composition and manufacturing process, but also related to magnetic field heat treatment process. The so-called magnetic field heat treatment is the application of an external magnetic field to the permanent magnet material during the decomposition reaction. After the magnetic field heat treatment, the magnetic performance of the permanent magnet material is improved. In addition, it is directional, with the largest paramagnetic field direction and the smallest vertical magnetic field direction, which is called anisotropy. For permanent magnetic materials that have not undergone a magnetic field heat treatment, the magnetic properties have no directionality, which is called isotropy. It should be noted that for anisotropic permanent magnets, the direction of the magnetic field during magnetization should be consistent with the direction of the magnetic field during magnetic field heat treatment, otherwise the magnetic properties will be reduced.

3. The permanent magnet material rises from room temperature to the highest working temperature and keeps it for a certain period of time before cooling to room temperature. The open-circuit magnetic flux is allowed to have an irreversible loss of not more than 5%. Therefore, in order to ensure the stable performance of the permanent magnet motor during operation, and to ensure that it does not have obvious irreversible demagnetization, the magnetization treatment should be carried out before use. The method is to heat up the magnetized permanent magnet material to the expected maximum working temperature and keep it for 2 to 4 hours to eliminate this part of the irreversible loss in advance.

4. The injection molding permanent magnet materials have different temperatures depending on the resin matrix used. The maximum operating temperature of nylon-based substrates should not exceed 150°C. The maximum long-term use temperature of polyphenylene sulfide matrix is 180℃. Injection molded magnets are also divided into anisotropic and isotropic. Anisotropic materials need to be oriented in a specific direction by applying an orientation magnetic field during the injection molding process.