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I have 10 cylindrical neodymium permanent magnets about 5mm in diameter, 5 mm long, embedded in a thermoplastic polymer. I want to demagnetize them without removing them, or heating them above 60 C - they must remain motionless, +/- 1 mm.

Note that the magnets are NOT all aligned in the same direction.

I can move a demagnetizer within 5 inches of the assembly, or place the entire (1m x .3m x .2m) assembly within a demagnetizer.

Yes - I thought about melting the plastic and replacing them - but all the other stuff must stay invariant :(

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According to a very comprehensive presentation from KJ Magnetics, it is likely that you will not be able to accomplish your objective.

The graphs and text indicate that you will have to know the correct composition information of your magnets and that you can only partially de-magnitize at 80°C and higher.

Even for those compositions that will accept a reduction of magnetism at 80°C, when the heat is removed, some magnetism will remain. I was intrigued to read that for some magnets, temperatures as high as 1000°C is required.

heat vs magnetism

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