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how to "repair" a motor magnet?

H

Herbert Widlok

Jan 1, 1970
0
Hi
Is it possible to remagnetize permanent magnets on stepper motor
rotor, that was partially demagnetized, when I have pulled it out of
stator? I knew that this could happen, but I never believed that this
will happen to me. And how they are mounting such motors in industry?

Thanks,
Michael
 
A

Arthur Jernberg

Jan 1, 1970
0
Sad to say but you may need to replace the complete motor as an assembly.
Unless you can get the manufacturere to send you a replacment magnet set.
 
S

Sam Goldwasser

Jan 1, 1970
0
Herbert Widlok said:
Is it possible to remagnetize permanent magnets on stepper motor
rotor, that was partially demagnetized, when I have pulled it out of
stator? I knew that this could happen, but I never believed that this
will happen to me. And how they are mounting such motors in industry?

In theory, it is possible. But as a practical matter, probably not.

They have to use a "keeper" when removing the rotor to maintain the
field.

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contact me, please use the Feedback Form at repairfaq.org. Thanks.
 
A

Andreas Schmidt

Jan 1, 1970
0
Herbert said:
Is it possible to remagnetize permanent magnets on stepper motor
rotor, that was partially demagnetized, when I have pulled it out of
stator? I knew that this could happen, but I never believed that this
will happen to me. And how they are mounting such motors in industry?

You could try replacing the magnet with a neodymium/rare earth magnet.
Those are much stronger than the ferrite stuff used in most motors, so a
much smaller magnet than the original one would do. Check out
http://www.wondermagnets.com/cgi-bi...ets_and_Magnetism;Permanent_Magnets;Neodymium

Neodymium magnets can also be found in hard drives, crack one open if
you have an older one lying around and take out the magnets to get a
feel for those beasts.

HTH,

Andi
 
F

FreeSkier

Jan 1, 1970
0
It's not that easy. A magnet is not just a magnet. Typically, the
magnetic material is installed on the rotor and placed in a magnetizing
fixture. The magnetizing coils are energized and this places the
desired pattern on the magnets. You can't necessarily tell what the
magnetizing pattern is by looking at the magnets (N-S are not always at
the ends). To further complicate things, the rotor was probably skewed,
meaning the magnetic "charge" on the rotor was not parallel.

In your case, you will definitely have to install magnetized magnets -
unless you build a magnetizing fixture. Either reverse engineer what's
remnant on the rotor or get a new motor.
 
H

Herbert Widlok

Jan 1, 1970
0
Thanks You all for replays. It seems that I will have to get new motor or
use old one that now have 50% of normal torque. I hope that this will
suffice for me.

Michael Widlok
 
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