Have you ever heard of demagnetization ? If you have, then do you know in what situations would demagnetization happen?
1: Magnets demagnetize after injection, the minimum temperature resistance of N series NdFeB is 80℃, and sometimes injection is basically above 120 ℃, so a short period of 2 to 3 seconds of injection can cause partial demagnetization.
2: The magnets may demagnetize after hot pressing.The glass fiber board is often used for hot pressing, and the temperature is above 150 ℃.
3: Magnets may demagnetize after heating in the oven.
4: Magnetic materials contain too much impurities that cause weak magnetism. This is the common result of most unfaithful purchase activities. For example, customers demand N35 series, but the unfaithful manufacturers select materials of the lower price, like N28, N33. Customers should not expect to be able to detect, because if the amount reaches 30K, it takes a long time to measure. (demagnetization may occur in 6 months, even two months is possible ). So a reliable supplier is really important. GME can be your faithful partner.
5: Impact results in demagnetization, such as high frequency impact, and so on. So the magnet should be be careful preserved in the course of transportation.
6: Materials contain lanthanum which may lead to magnet powderization.
7: The high magnetic environment makes the magnet itself disappear or change the N/S pole This may happen with the help of magnetizer/demagnetizer.
All in all, 90% of the reasons of demagnetization can be summarized as follows:
High temperature
Unqualified raw materials
High frequency impact
High magnetic environment