Description of Bonded Magnets

• Bonded magnets are composites of permanent magnetic powder(s) embedded in a non-magnetic matrix

• The matrix is typically a thermoplastic or elastomeric binder

• Standard processing techniques are extrusion, injection molding, compression bonding, and calendering

• Exhibit excellent mechanical properties compared to fully dense rare earth and ferrite magnets.

• The end product has a good finish and dimensional tolerances requiring no finishing operations

• Injection-molded magnets can be formed into complex shapes and be insert or over-molded directly onto other components to produce assemblies

• The non-magnetic binder lowers the density of the magnet and dilutes the contribution of the magnetic powder

• They generate less magnetic output per unit volume than fully dense magnets

• The two most common magnetic powders are isotropic NdFeB and hard ferrite

• Bonded magnets can be magnetized multi-polar, such as an N-S-N-S pattern on the outer diameter since the material is isotropic