The value of the reverse magnetic field strength required to reduce the magnetic induction strength to zero when the magnet after saturation magnetization of the strong magnet technology is reversely magnetized is called magnetic coercivity (Hcb). However, the magnetization of the magnet is not zero at this time, but the reverse magnetic field and the magnetization of the magnet cancel each other out. (The external magnetic induction intensity is zero.) At this time, if the external magnetic field is cancelled, the magnet still has a certain magnetic performance. The coercive force of NdFeB is generally above 11000Oe.

A magnet is magnetized by an external magnetic field in a closed circuit environment to technical saturation and then the external magnetic field is cancelled. At this time, the magnetic induction strength exhibited by the magnet is called remanence. It represents the maximum magnetic flux value that a magnet can provide. It can be seen from the demagnetization curve that it corresponds to the case when the air gap is zero, so the magnetic induction strength of the magnet in the actual magnetic circuit is less than the remanence. NdFeB is the highest practical permanent magnetic material with the highest Br found today.

The strength of the reverse magnetic field that a strong magnet needs to reduce the magnetization of the magnet to zero is called the intrinsic coercive force. Intrinsic coercive force is a physical quantity that measures the magnet's resistance to demagnetization. If the external magnetic field is equal to the intrinsic coercive force of the magnet, the magnetism of the powerful magnet will be basically eliminated. The Hcj of NdFeB will decrease as the temperature increases, so you should choose a high Hcj grade when you need to work in a high temperature environment.