A Simple Method for Demagnetizing Large NdFeB Permanent Magnets

摘要

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 x 7 cm x 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 degrees 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.