A Simple Method for Demagnetizing Large NdFeB Permanent Magnets

Prior to processing magnetic NdFeB material for recycling, it must be demagnetized. Here, we demonstrate a simple low-cost method. Large blocks of NdFeB permanent magnets of dimension 10 cm × 7 cm × 2 cm and with easy axis along the shortest dimension are shown to demagnetize when heated on a planar induction heating device. The initial magnetization of the magnets is reduced by a factor of 10 within a period of 30 min, in which the surface temperature of the magnet reaches 225 °C. This method simplifies the demagnetization process of the permanent magnets in wind turbine generators as part of the rapidly increasing demand for improved recycling capabilities of permanent magnets.