Powerful magnets generally refer to NdFeB magnets, which are mainly composed of rare earth praseodymium neodymium and common element iron. At present, this material is widely used in the market, but strong magnets often encounter magnetic force weakening or disappearing during use. It happens frequently. We summarize the reasons for magnet degaussing as follows:
1. After the magnet is demagnetized or demagnetized after injection molding, the minimum temperature resistance of the NdFeB N series is 80°C, and sometimes the injection molding is basically above 120°C, so a short injection of 2 seconds to 3 seconds may cause partial demagnetization imagine.
2. The magnet is degaussed after hot pressing, often using glass fiber board hot pressing, the temperature is above 150 ℃.
3. The magnets are demagnetized after baking in the oven.
4. The magnet material contains too many impurities, resulting in weak magnetism. This is the common result of most petty and cheap buyers. Because of the quotation, shop around and choose the manufacturer with the lowest quotation. Obviously, the customer’s request is to use N35 grades, but the bad manufacturers with ultra-low quotations use N28 and N33 materials. Customers don’t expect to be able to detect it. If the quantity reaches 30K, should they be measured slowly with a fluxmeter? (Demagnetization occurs in as short as 6 months, and demagnetization occurs as quickly as two months), a reliable and stable supplier is really important. How can it be made for you with N35 materials without that price? Moreover, some merchants' magnets are used for packaging. Anyway, they can absorb them, and the material waste is waste.
5. The impact will lead to demagnetization of the magnet, such as high-frequency impact, etc., so be careful during transportation.
6. The material contains metal sulphate, which leads to powdering of the magnet, etc.
7. In a high magnetic field environment, the magnetic force of the magnet itself disappears or the N/S pole changes (magnetizer and demagnetizer).
To sum up, the reasons for the above demagnetization (demagnetization) are basically 90%. There are 4 points, high temperature demagnetization, demagnetization due to material problems, high frequency impact demagnetization, and high magnetic field demagnetization.