Magnetic Force

[dubba24]

Hello,

I am working on a project where I need to be able to calculate the force required to separate a small disc magnet from a piece of metal. Could someone point in the direction to where I can find the equations necessary to complete my task?

Thank You

 

[gphatch]

An empirical formula that might help:

F = 0.577 x B^2 x A

Where F = force [in lb-f]
and B = flux density at the interface [in Gauss]
and A = area in contact [in inches ^ 2].

The constant above [0.577] may change with extremes of geometry.

Check out the Field Calculator tool at our web site:

http://www.dextermag.com

Go to Tools -> Field Calculators

to see online calculators for disks and squares.

Hope this helps!

Best wishes

Gareth Hatch
Director of Technology
Dexter Magnetic Technologies Inc.

 

[dubba24]

Thanks for the help! I have tried the equation that you gave me, but the units that are being returned do not make sense to me. Mathcad returns (kg^2m^2)/(s^4A^2) which reduces to N^2/A^2. I have found that dividing the result from your formula by the permeability of vacuum will return a value in newtons. I then divide that by g to get a result in ounces... Am I anywhere near being on the right track?

Morgan Mead

 

[gphatch]

As I said, this is an empirical formula, used for many years by magnetic circuit designers - the "0.577" constant is supposed to take care of unit conversion issues as well as account for geometry and permeability.

The key here is that F is directly proportional to B^2 x A.

Gareth

 

[dubba24]

Thanks for you help!