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#1
Old 01-26-2004, 09:08 AM
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How do I remagnetise a magnet?

I'm at work and I've been asked to remagnetise a couple of magnets, only problem is I have no idea how! They're just normal bar magnets, nothing special, and they don't need to be *super* powerful, just strong enough to move iron filings, nails, etc.

Thanks,
Tuco.
#2
Old 01-26-2004, 09:33 AM
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Location: Richmond, VA
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The very simplest method is to use a good magnet. Take the good magnet and stroke it in one direction only along the length of the magnet to be remagnetized in a line with the intended poles. Repeat this several times.
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#3
Old 01-26-2004, 10:00 AM
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Posts: 12,684
The usual method is to put the magnet in an alternating magnetic field. This causes the field in the magnet to cycle through the entire hysteresis curve. Then the applied field is gradually reduced to zero which results in demagnetization.
#4
Old 01-26-2004, 10:03 AM
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Holy cow! It's early in the morning and I read remagnetize as demagnetize. Follow QED's method.

As a bonus, is your are ever asked to demagnetize you now know how. We offer a complete service from A to Z whether or not it is asked for.
#5
Old 01-26-2004, 10:16 AM
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Location: KNOXTN
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It all depends on how strong?

Using another magnet works under centain conditions.
The magnet must be stronger than the finished magnet you wish to achieve.

Magnets are magnetized commercially with specially wound heavy duty cable/wire.
coils. The piece to be magnetized is placed inside the coil. A large amperage DC current is discharged through the coils to produce a very strong magnetic field and the job is done.

You can wrap a soft iron or steel bar with as many turns of # 10 or 12 wire as possible. Connect one end of the wire to a car battery. Then apply the other end of the wire to the other battery terminal, BRIEFLY. Voila...... the bar is (re)magnetized.

you can repeat this two or three times to enhance the magnetic field of the bar.

Wear safety glasses and/or face shield while working around batteries!
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#6
Old 01-26-2004, 06:40 PM
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Location: Seattle WA USA
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Quote:
Originally Posted by Tuco
I'm at work and I've been asked to remagnetise a couple of magnets, only problem is I have no idea how! They're just normal bar magnets, nothing special, and they don't need to be *super* powerful, just strong enough to move iron filings, nails, etc.

Thanks,
Tuco.
Arbor sells an expensive re-magnetizer:

http://arborsci.com/Products_Pag...p#Remagnetizer


Much easier: get yourself a neodymium supermagnet. Stroke it along the bar magnets a couple of times on both sides and they'll be remagnetized. Neodymium magnets can be found for cheap at http://wondermagnet.com
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#7
Old 01-27-2004, 06:10 AM
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Join Date: May 2002
Location: SE USA
Posts: 404
I frequently have to reset some 2-inch alnico magnets that we use to bias during deposition. Granted, I have tools not available to others. I use a 1.6 tesla electromagnet. The hard part is to keep them from slamming into the poles.
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