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Mu-Metal + N52 grade magnet.

  1. Jun 22, 2013 #1
    Hey guys.

    I was just wondering about Mu-Metal.
    I'm sure you guys know what a Magnet "Keeper" is.

    If I was to take a thick piece of Mu-Metal and lay it across a magnet from the North to the South pole, would this act as a Keeper?

    I'm trying to reduce the amount of flux loss over time, and 'i've heard that a "Keeper" can help a lot with that. I know my magnets are VERY strong, so I will be sure to use a 1/16th inch thick
    piece of Mu-Metal to be adequate.

    But would this even work? Or would it make the degradation of the flux even worse?
  2. jcsd
  3. Jun 23, 2013 #2


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    I don't know about your particular magnet and keepers. I can say that mu=metal is a poor choice as a keeper because it saturates at extremely low applied fields. It's intended to shield sensitive instruments operating in small fields and is pretty useless for high ones. Soft iron or mild steel are better materials for use in intense fields. Depending on the strength and size of your magnet, 1/16" may not be adequate.
  4. Jun 23, 2013 #3
    Thanks for the reply.

    Ok so Mu Metal is most probably not a good material for acting as a keeper.
    Well I work in a machine shop and we have lots of low carbon / mild steel laying around im sure
    I could use instead.

    Thanks again!
  5. Jun 25, 2013 #4
    ok I have one more question.

    Lets say I use Mild steel or soft iron.
    If I use either of these as a keeper, wont they eventually generate there own
    magnetic field?

    I guess what I'm saying is that I don't want to use a material as a keeper that will itself become
    some sort of a magnet. Isn't this what happens with Iron connected directly to a magnet?

  6. Jun 25, 2013 #5


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    BTW, rare earth magnets don't really need keepers. They don't spontaneously demagnetize, and are highly resistant to demagnetization even around other magnets.
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