Environmental temperature. The sintered NdFeB has negative temperature coefficient (alpha Br<-0.13%/ alpha Hcj<-0.6%/ C, c), so the use of instant maximum temperature environment and sustained the highest temperature will produce different degrees of magnet demagnetization, including reversible and irreversible, recoverable and unrecoverable.

Environmental humidity. NdFeB itself is easy to corrosion and oxidation. In general, we use surface treatment to protect permanent magnets, but it can not fundamentally solve the influence of ambient humidity on the magnet. The drier the environment, the longer the magnet will last.

How to measure the magnetic performance? There are three main parameters: Br (Residual Induction), remanence Gauss, is a measure of the magnet foreign can provide magnetic field parameters; the coercivity of Hc (Coercive Force), Oersteds, is a measure of resistance to demagnetization parameters; energy product of BHmax, Gauss-Oersteds, is a physical quantity characterized by energy storage how much energy.