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Author Topic: Demagnetization risk of Neo magnets in repel mode?  (Read 25169 times)

Honk

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Demagnetization risk of Neo magnets in repel mode?
« on: July 13, 2007, 10:14:22 AM »
There is a lot of people telling us that placing magnets in repel mode will demagnetize them.
But many of those people have used inferior magnets in their test, like cheap ferrite.
And then we hear over and over again that repelling magnets will demagnetize them.
But that might not be true if you are careful and use neomagnets of the same size,
shape and strength in repel mode. Then the fields are equal in strength.

Please read the question at this link. It explains my concern.
http://www.overunity.com/index.php/topic,2451.msg39543.html#msg39543
I think we have to sort out the risk when using good quality NdFeB magnets.

So, if we have two equally strong neo magnets of the same size and shape
they should be able to operate in repelling mode without demagnetization.

I have attached a demagnetization graph on several types of magnets.
But I have trouble understanding how to read it. Can someone here explain
how to see what type of field it takes to demagnetize the N38 in the graph?
It might clarify wether it can withstand or not to be demagnetized of a similar
external field as the N38 holds.
« Last Edit: July 13, 2007, 01:56:19 PM by Honk »

Earl

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Demagnetization risk of Neo magnets in repel mode?
« Reply #1 on: July 13, 2007, 01:20:09 PM »
There lot's people telling us that putting two magnets in repel will demagnetize them.

The above sentence makes absolutely no sense because the noun "magnet" is missing an adjective.

But many of those people have used inferior magnets in their test, like cheap ferrite.
And then we hear over and over again that repelling magnets will demagnetize them.
But that might not be true if you are careful and use neomagnets of the same size,
shape and strength in repel mode. Then the fields are equal in strength.

Please read the question at this link. It explains my concern.
http://www.overunity.com/index.php/topic,2451.msg39543.html#msg39543
I think we have to sort out the risk when using good quality NdFeB magnets.

So, if we have two equally strong neo magnets of the same size and shape
they should be able to operate in repelling mode without demagnetization.

If people would simply ask NEO manufacturers this question instead of speculating, they would have the answer:

Two NEO magnet can not weaken or demagnitize each other in repel mode.  If not heated excessively or violently vibrated, the great-great-grandchildren of your great-great-grandchildren will not be able to measure any weakening of NEOs in repell mode.

People who say that NEOs can demagnetize themselves, usually can not tie their shoes on in the morning.

End of discussion.

Liberty

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Re: Demagnetization risk of Neo magnets in repel mode?
« Reply #2 on: July 13, 2007, 02:57:29 PM »
Earl,

Did your information come from a Neo manufacturer or have you been working for one?
I have not noticed any weakness from using them in a working magnet motor (using my design).  Do you have any figures when magnets are used at certain velocities with one another?  Or does this make any difference to the "pinning material" within the magnet?

Thanks.

Duranza

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Re: Demagnetization risk of Neo magnets in repel mode?
« Reply #3 on: July 13, 2007, 03:39:15 PM »
My theory is that a stronger magnet will demagnetize the weaker one... If the magnets are all the same material, shape, size and strenght no demagnetization should take place. no matter what configuration you place them in...

Honk

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Re: Demagnetization risk of Neo magnets in repel mode?
« Reply #4 on: July 13, 2007, 03:54:42 PM »
My theory is that a stronger magnet will demagnetize the weaker one....
If the magnets are all the same material, shape, size and strenght no demagnetization
should take place. No matter what configuration you place them in...

That's my point exactly, but it would be nice to have some calculations or graph understanding
to back this idea instead of just guessing.
I'd like to design a Wankel motor at repel mode but then I need to know more about the risks.

Hey all of you guys out there. Please tell us what you know about this subject. (Other than guesses)

Bulbz

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Re: Demagnetization risk of Neo magnets in repel mode?
« Reply #5 on: July 13, 2007, 04:46:54 PM »
Try this experiment...

Get hold of a donut shaped magnet, one from the back of a loudspeaker will do just fine, and break it into two pieces. Now try and put the two pieces back together... They will repell each other apart. So the people that say magnets can not be used in repel mode, are they saying that a donut magnet de-mags all by it's self ?. Hmmm !.

Honk

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Re: Demagnetization risk of Neo magnets in repel mode?
« Reply #6 on: July 13, 2007, 04:56:54 PM »
Try this experiment...

Get hold of a donut shaped magnet, one from the back of a loudspeaker will do just fine, and break it into two pieces. Now try and put the two pieces back together... They will repell each other apart. So the people that say magnets can not be used in repel mode, are they saying that a donut magnet de-mags all by it's self ?. Hmmm !.

http://www.overunity.com/index.php/topic,2451.msg39543.html#msg39543

Bulbz

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Re: Demagnetization risk of Neo magnets in repel mode?
« Reply #7 on: July 13, 2007, 06:11:26 PM »
@ Honk...

Yeah, I understand the two magnets of equal size and strenght wont de-mag in repel mode, but... What if the two broken pieces are from the same magnet but are different sizes. Lets say that when the magnet is broken in two but one piece ends up as 1/3 of the parent magnet and the other piece is 2/3. Will the two un-equal parts of the same magnet de-mag each other in this scenario ?.

Honk

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Re: Demagnetization risk of Neo magnets in repel mode?
« Reply #8 on: July 13, 2007, 06:41:51 PM »
Good question. I don't know.... Perhaps someone else here can help?

Nali2001

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Re: Demagnetization risk of Neo magnets in repel mode?
« Reply #9 on: July 13, 2007, 09:01:40 PM »
I don't think that a static repulsive field like clamping 2 magnets together will change much, since the magnetic domains will 'holdup'. But when the repulsive field is pulsing it a different story, probably much like hammering a nail in wood. You can let a 200kg hammer rest on a nail and it won't sink the nail into the wood. Because the structure of the wood will 'holdup' the static pressure of the hammer. But you CAN take a 0.1kg hammer and hammer the nail with a rate or frequency and it will drive the nail in the wood. The actual 'action matters'
I thing...

Honk

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Re: Demagnetization risk of Neo magnets in repel mode?
« Reply #10 on: July 13, 2007, 09:52:44 PM »
Sorry, but I don't buy the hammer theory when it comes to magnets.
There is no mass involved when presenting two flux fields to each other.
We need some hardcore facts and stop guessing.
I will have to contact a manufacturer and hear what they have to say about it.

Earl

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Demagnetization risk of Neo magnets in repel mode?
« Reply #11 on: July 14, 2007, 01:39:04 AM »
You all have no idea of how NEO material is magnetized and what physical pieces and energy are necessary.  In order to magnetize NEO material, one needs high-voltage capacitors discharging mucho mucho Amperes into a magnetizing coil.  The magnetizing coil has ferric material in it, which funtions at first, but as the Amperes climb the iron saturates and the magnetizing coil becomes an air-core coil, which needs then still more amperes to saturate the NEO material.  By mucho Amperes, we are talkiing about tens, hundreds, thousands, even tens of thousands of Amperes, even if only for a short time.  Lots and lots of joules.

A NEO magnet can neither saturate NEO material nor demagnitize another NEO magnet.

Forget completely about successfully magnetizing or demagnetizing one NEO magnet by another.
NEO magnets are not called super magnets for no reason.

Earl

Bulbz

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Re: Demagnetization risk of Neo magnets in repel mode?
« Reply #12 on: July 14, 2007, 04:53:01 AM »
@ Earl...

Thank you for the enlightenment ;D.

Honk

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Re: Demagnetization risk of Neo magnets in repel mode?
« Reply #13 on: July 14, 2007, 08:55:32 AM »
I don't buy it just yet. I'd like some more information.
Yes, we can all read about the magnetization process of neo magnets on the internet
but there's very litte or no information on the demagnetization process except heat.

Have anybody here ever had a neo demagnetize or getting somewhat weaker when repelled?
Or have all those spreading the rumor used ferrite or alnico magnets.

Earl

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Demagnetization risk of Neo magnets in repel mode?
« Reply #14 on: July 14, 2007, 01:28:53 PM »
I don't buy it just yet. I'd like some more information.
Yes, we can all read about the magnetization process of neo magnets on the internet
but there's very litte or no information on the demagnetization process except heat.


Did it ever occur to you that that is the only way to demagnetize a NEO magnet with the exception of putting it into a HV magnetizer and zapping it halfway?


Have anybody here ever had a neo demagnetize or getting somewhat weaker when repelled?


This never happens.


Or have all those spreading the rumor used ferrite or alnico magnets.


Finally, finally the light goes on!  It sure took a while until you understood.  Ferrite and alnico magnets not only demagnitize in repelling mode, they demagnitize just sitting there.

Why do you think all alnico horseshoe magnets always are delivered with an iron keeper bar?
Why is it called a keeper bar?

Why are NEO magnets the only ones that are manufactured in thin discs?

People who say NEO magnets can demagnitize in repelling mode are dumb sh!ts.

For the very last time, NEO magnets are SUPER magnets and have not the slightest link whatsoever with all previous magnetic materials such as ferrite or alnico.  NEOs are in a completely different universe than all other previously discovered magnetic material.  You can not compare apples with zebras.

If you don't buy it, that is your problem.

Regards, Earl