General magnets will be demagnetized when the working temperature reaches above 80 degrees. For example, ferrite magnets, rubber magnets, and N-grade NdFeB magnets will be demagnetized when the working temperature reaches 80 degrees. The principle is that a magnet is composed of many small magnetic units arranged in the same direction. When the temperature rises and reaches a critical value, the trend of thermal motion exceeds the effect of magnetic force, so that the arrangement of these units is no longer regular, so that it loses its magnetism in a macroscopic view. So how to choose high temperature magnets?

1. Choose NdFeB high temperature resistant magnets between 80°C and 230°C working temperature. The specific grades are as follows:

1. Working temperature between 80 degrees and 100 degrees: M-grade NdFeB high temperature magnets can be used.

2. Working temperature between 100 degrees and 120 degrees: H-grade NdFeB high temperature magnets can be selected.

3. Operating temperature between 120 degrees and 150 degrees: SH-grade NdFeB high temperature magnets can be used.

4. Operating temperature between 150 degrees and 180 degrees: UH grade NdFeB high temperature magnets can be used.

5. Working temperature between 180 degrees and 200 degrees: EH grade NdFeB high temperature resistant magnets can be selected.

6. Working temperature between 200 degrees and 230 degrees: You can choose AH-grade NdFeB high temperature magnets.

2. Select samarium cobalt high temperature magnets between 230°C and 350°C working temperature. The specific grades are as follows:

1. Working temperature between 230 degrees and 250 degrees: 1:5 samarium cobalt can be used.

2. Working temperature between 250 degrees and 350 degrees: 2:17 samarium cobalt can be used.

3. At present, only AlNiCo magnets can be selected for high temperature magnets with a working temperature above 350 degrees.