Time before demagnetization?
Time before demagnetization?
(OP)
If two neodymium magnets were held north to south with 1cm separating them, how quickly would they demagnetize under the following conditions:
- Average temperatures (say -10 to 130 degrees F at the
extremes)
- Exposed to air
- high pressures (possibly spiking to as much as 400psi)
Here is a link to the exact magnets I wish to use:
http://www .kjmagneti cs.com/pro ddetail.as p?prod=BX0 41%2DN50&a mp;cat=168
I realize there is no specific answer to this question, but I would just like to know a ballpark figure. If someone could tell me if I'd be looking at 5 years or 5 days before I see a noticeable decrease in the magnets' magnetic fields that would be great. Thanks.
- Average temperatures (say -10 to 130 degrees F at the
extremes)
- Exposed to air
- high pressures (possibly spiking to as much as 400psi)
Here is a link to the exact magnets I wish to use:
http://www
I realize there is no specific answer to this question, but I would just like to know a ballpark figure. If someone could tell me if I'd be looking at 5 years or 5 days before I see a noticeable decrease in the magnets' magnetic fields that would be great. Thanks.
RE: Time before demagnetization?
RE: Time before demagnetization?
But in your example the magnets are attracting, so there is not demag field at all.
With lower coercivity grades you can see fields slowly decay over months or years.
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RE: Time before demagnetization?
RE: Time before demagnetization?
At the temperature ranges you are talking about, I don't think you'd see much demagnafication even if the the same poles were in contact.
A test to do; put two magnets in a glass tube and see how far apart they repel. Then clamp them together for a week. Then remeasure the repelling distance in a glass tube. It will remain the same.
RE: Time before demagnetization?
RE: Time before demagnetization?
RE: Time before demagnetization?
The permeance of the part you refrence is very low and will experience demagnetization much sooner than the basic properties would suggest. Particularly if subjected to N-N orientation and temperature.
Mike
RE: Time before demagnetization?
MagMike: I do indeed have a project that I am working on. My questions are not purely theoretical, but due to the nature of my project I would rather not disclose exactly what it is. However, if I am in danger of being removed from the forum because of my questions I may be able to provide some information.
RE: Time before demagnetization?
Mike
RE: Time before demagnetization?
I apologize for not giving adequate details concerning my project.
RE: Time before demagnetization?
TTFN
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RE: Time before demagnetization?
I disagree. In a brushless motor, the stator and rotor fields rotate in synchronism.
I don't know how one would go about simulating this. Do any of the magnetic FEA programs model heating in the magnets?
RE: Time before demagnetization?
The field will not be very great given the airgaps. But the frequency is high. Eddy current heating can take place in seconds.
AgainstOdds these details you have now provided are generally adequate. You have told us the magnet and the geometry. Plus the important detail of frequency.
Mike