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Repolarizing Neodymium Magnets

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tcmtech

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I got a possible project I am planning to do but I need to change the pole location one several neodymium hard drive magnets.
Right now the are north and south on the same side but at opposite ends of each other. I need to change that to a face polarization. Top north, bottom south.

I already set them to no poles by heating them up to the Currie point, but I am not having much luck getting them back to full strength with the new pole configuration.

Anyone know the secret to how they supercharge the neodymiums at the factory?
 

Speakerguy

Active Member
With a BIG ass magnet charger. Technical term.

Honestly, I think you are out of luck on this one. I've seen the magnet chargers for loudspeaker motors and those are only for ceramic 5 magnets. NdFeB >=35MGOe? Yikes.
 
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Sceadwian

Banned
That's the hard part TCM. To set them, you need to heat them up to the curie point. Keep them there, then apply an electromagnetic field and then cool the magnets down while the field still exists. BIG coils massive current to create the static field that you freeze in your magnets which you place in the center, and don't try to cool them down too fast, they're ceramics or like them, they'll pop =)
 
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tcmtech

Banned
Most Helpful Member
hmm... I do have big ass electromagnets! Several kw peak in fact!

Would reheating them to the Currie point and sticking them in the middle of two electromagnets possibly work?
Shimmed with aluminum so as to not crush the neodymium magnets of course.
 

The Electrician

Active Member
At this site (WONDERMAGNET.COM - NdFeB Magnets, Magnet Wire, Books, Weird Science, Needful Things) you will find:

"Manufacturing: NdFeB magnets are complicated to manufacture. The powdered NdFeB material is packed in molds, then sintered. The non-magnetized 'magnets' are then shaped to the correct size and plated. To magnetize them, they are placed in a very expensive machine that generates an extremely high-powered magnetic field for an instant, using high-voltage capacitor discharge and coils. The polarity of the finished magnet depends on how it was oriented in the magnetizing machine, and how the particles in the sintered mixture were oriented. So that makes home manufacture impossible."

I think I've read somewhere that you need to apply fields of 50,000 Gauss, maybe even as high as 100,000 Gauss to magnetize a NdFeB magnet.

I think you'd be more likely to succeed by getting a magnet from one of these places (Forcefield - Otherpower - Wondermagnet Online Store) and then use a mototool to grind it to size, keeping a water jet on it while you grind.
 

Sceadwian

Banned
TCM I doubt permanent magnets would work you need a stronger field than that. You could try it with your electromagnet but I'd imagine the field you get to stick would be weak compared to the original field. Hard Drive magnet are about the most highly magnetized magnets I've ever used.

Gaussboys Super Magnets
is another site. I've bought magnetic silly putty from Crazy Aarons before and they sell gaussboy magnets. Some of the strongest ones they sell have to be kept away from each other because they so strong if they're allowed to snap together they'll shatter. By the way check out Crazy Aarons putty world =) I stepson gets a lb every year, great stuff and the magnetic putty is fun.
 
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