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 <inline-formula> <tex-math notation="LaTeX">\times 7 </tex-math></inline-formul...

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Bibliographic Details
Published inIEEE transactions on magnetics Vol. 56; no. 8; pp. 1 - 6
Main Authors Bahl, Christian R. H., Eder, Martin A., Boland, Greg, Abrahamsen, Asger B.
Format Journal Article
LanguageEnglish
Published New York IEEE 01.08.2020
The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subjects
Demagnetization
Electromagnetic heating
Generators
Induction heating
Magnetic field measurement
Magnetic separation
Magnetism
permanent magnet
permanent magnet generators
Permanent magnets
Recycling
Temperature measurement
Turbogenerators
Wind turbines
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Summary: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 <inline-formula> <tex-math notation="LaTeX">\times 7 </tex-math></inline-formula> cm <inline-formula> <tex-math notation="LaTeX">\times 2 </tex-math></inline-formula> 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.
ISSN:0018-9464
1941-0069
DOI:10.1109/TMAG.2020.3002098