Permeability

[Anvil]

Hi. Does any of you have a list of permeabilties of different metals. I would like to know permeability of copper, u-metal, stainless steel, aluminium and steel. What other things matter to magnetic shielding than permeability?

[weinstro]

I would like to know permeability of copper, u-metal, stainless steel, aluminium and steel. What other things matter to magnetic shielding than permeability?

Relative Permeabilities
Iron 150
Permalloy 8,000
Nickel 110
Steel 50
Mu metal 20,000
Copper 1
Aluminum 1
Stainless 1 (depends on composition)

Personally, I would be looking at how the material is to work with, i.e., cutting, drilling, welding, bending, etc.

Regards,

Rob

[Anvil]

Hi. What happens to stainless steel`s permeability when it is heattreated or welded? Thank you for your list.

[Steve Eddy]

Originally posted by Anvil
What other things matter to magnetic shielding than permeability?

Thickness and saturability come to mind. Generally the higher permeability materials saturate at much lower levels and once the material saturates, it's no longer effective as a shield.

se

[johnferrier]

I like to refer to figure 16 here: http://www.analog.com/UploadedFiles/...6254AN-347.pdf

BTW I like steel's shielding ability (easier to get and work with than mu-metal).


JF

[jneutron]

Originally posted by Anvil
Hi. Does any of you have a list of permeabilties of different metals. I would like to know permeability of copper, u-metal, stainless steel, aluminium and steel. What other things matter to magnetic shielding than permeability?

John...nice graph, thanks..

Anvil...skin depth of the material plays a role also.

depth (cm) = 5033 * sqr(p/uf)

p is resistivity in ohms per centimeter cubed
u is permeability for low flux densities
f is frequency

When SS is welded, it can allow precipitation of carbon, rendering it magnetic. Also, it can become slightly magnetic when machined.

Cheers, John

[sreten]

Originally posted by Anvil
What other things matter to magnetic shielding than permeability?

Fresh air, i.e. distance is much cheaper then anything else.

sreten.