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Thread: Dropping permeability of (1018?) fillister head 'bucker type pole screws

  1. #36
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    Quote Originally Posted by Diablo View Post
    I don’t believe the value given in that table for pure iron. The value given for 1010 steel is correct and should be the same for pure iron.
    I found several sources that confirm the value for pure iron.

    E.g.: https://www.thoughtco.com/table-of-e...ctivity-608499
    https://www.researchgate.net/figure/...fig3_228407964
    https://www.thebalance.com/electrica...metals-2340117

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    Last edited by Diablo; 01-10-2020 at 12:01 AM.

  3. #38
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    Thanks, this table I also found. It confirms the pure iron conductivity value given by wikipedia.

    The google books link doesn't show text.

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    Quote Originally Posted by Helmholtz View Post
    Thanks, this table I also found. It confirms the pure iron conductivity value given by wikipedia.

    The google books link doesn't show text.
    That’s strange, the google book opens when I click on it.

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  5. #40
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    Is the effect of conductivity strictly limited to eddy currents or are we talking about something else entirely?
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  6. #41
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    Quote Originally Posted by Diablo View Post
    That’s strange, the google book opens when I click on it.
    Book doesn't open here. Maybe due to European copyright regulation.

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    Italy here, the Google book link opens just fine.

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  8. #43
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    Is the effect of conductivity strictly limited to eddy currents or are we talking about something else entirely?
    Yes, it's all related to Eddy currents. But conductive ferromagnetic cores show an additional phenomenon that tends to increase the typical Eddy current effects caused by conductive but non-magnetic parts (like reduced inductance and increased damping/losses).
    This is the magnetic Skin effect (see Zollner, "Physics of the Electric Guitar", https://www.sciencedirect.com/scienc...04885300004145, https://www.researchgate.net/publica...ower_frequency )

    The Eddy current rotating around the magnetic axis of the core produces a counter H field inside the core which reduces total flux. As a result the effective permeability of the core drops with increasing frequency.
    Eddy currents increase with conductivity and so does the magnetic skin effect.

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    Last edited by Helmholtz; 01-12-2020 at 05:02 PM.
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