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How to Judge the Quality of Sintered NdFeB Magnets?

Before clarifying the usable temperature of sintered NdFeB magnets, it is necessary to clarify the grade of sintered NdFeB magnets. 

Ⅰ. Grades of sintered NdFeB magnets:

N: low coercive force;

H: high coercive force;

UH: ultra-high coercive force;

There is also a more detailed classification: the larger the number, the higher the magnetic energy product; other grades are divided into corresponding grades according to the coercive force and working temperature range.

Ⅱ. Factors affecting the magnetic force of NdFeB magnets

Whether the magnet is demagnetized or not and the length of life depends entirely on the selection of the temperature-resistant material of the magnet used.

1. The existence of alternating magnetic field. Anyone who has a certain understanding of NdFeB magnets knows that the magnets are divided into N, S poles or multi-poles. If there is another magnetic field around the magnet, it will cancel the magnetic force of a part of the magnet. This is also what people say that it will demagnetize in the range of operating temperature.

2. Mechanical vibration. This has something to do with assembly. During the assembly process, the NdFeB magnet rubs against the product. Because the material of the magnet is fragile, the body wears out and the size becomes smaller. As a result, the magnetic force will gradually weaken.

3. Temperature. Due to the types of magnets (for example: ferrite magnets, NdFeB magnets, bonded NdFeB magnets, AlNiCo, SmCo, FeCrCo, permanent ferrite, bread magnets, rubber magnets, refrigerator magnets, magnetic buckles, There are dozens of types of health care magnets, injection molded ferrite, etc.) and materials, all of which have corresponding temperature limits. Generally speaking, during the use of the product, there will be no demagnetization when the temperature is lower than the limit of the magnet.

The operating temperature of NdFeB magnets depends on the magnetic properties of the magnet itself and the selection of the working point. The working point of the magnet can be expressed by the magnetic permeability of the magnet. For the same magnet, the higher the permeability of the magnetic circuit (that is, the more closed the magnetic circuit is), the higher the operating temperature of the magnet and the more stable the performance of the magnet. Therefore, the operating temperature of the magnet is not a definite value, but changes with the degree of closure of the magnetic circuit.

If the actual working temperature is close to the use temperature, and the magnet has a large demagnetization, then either the magnetic circuit must be improved to increase the magnetic permeability of the magnetic circuit; or a higher grade of performance must be selected to ensure the normal operation of the NdFeB magnet.

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