# How can I determine the type of magnet used in a DC motor?

I repair electrical motors in a workshop and sometimes I must repair permanent magnet DC motors and other motors that use permanent magnets. I need to specify type of permanent magnet (Ferrite or Alnico or rare earth, etc.) by a simple method. Is there a way to do this?

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get hold of one of these ? niton.com/en/niton-analyzers-products – anna v Jan 21 '13 at 11:37
Measure the density and look at the physical appearance of the surface. I think those two factors would probably narrow it down quite a bit. If that's not enough, maybe measure the dipole moment based on deflection of a compass, and determine the ratio of dipole moment to mass, $D/m$. – Ben Crowell May 3 '13 at 2:39