What factors will effect performance of magnet?
Ambient temperature: since sintered NdFeB magnet has negative temperature coefficients of remanence Br and coercivity Hc, the temperature will demagnetize the magnet to some extent, reversibly or irreversibly. The loss is also recoverable or irrecoverable.
Environment humidity: NdFeB magnet usually has to be coated to prevent it from corrosion because the naked material is very easy rusted and oxidated. Dry environment will result a long life of the magnet usage.