Plastic bonded magnets

Plastic bonded magnets are being used in an increasing variety of products. They are produced by embedding hard ferrite or rare earth magnet powder in plastic. First, the magnet powder and the plastic are mixed in special equipment. Then the mixture is pressed or processed in modified injection moulding machines. This process achieves very narrow tolerances, so that postprocessing is normally unnecessary.

History
Development of plastic bonded, injection moulded hard ferrite magnets: End of the 1950s
Use: Beginning of the 1960s

Development of plastic bonded, injection moulded NdFeB magnets: Middle of the 1980s
Use: End of the 1980s

Production begins at MS-Schramberg
1985

Compound preparation
Plastic bonded, injected magnets consist of two components: magnet powder (see Hard Ferrite/Rare Earth Magnets) and thermoplastic matrix material
(PA 6, PA 12, PPS). The plastic granulate and the magnet powder are compounded in a hot kneader or twin screw extruder and then granulated.

Type of material
Composite material

Manufacturing process
Press process and injection moulding process

Application areas and particular properties
Plastic bonded, injection moulded magnets can be shaped in much the same way as technical plastic components. Further mechanical processing of the injection moulded magnets is usually unnecessary.

Plastic bonded, overmoulded magnets
By overmoulding inserts with magnet compound, magnets with axes, bushings or other functional elements can be combined.