BREMAG plastic bonded magnets are used extensively in electrically driven pumps, either as part of the driving element such as the magnetic rotor (or stator) in an electric drive or as an attached magnetic coupling. The latter is used to mechanically separate the motor from the impeller of the pump in order to isolate the electric coils and bearing mechanisms from whatever medium is being pumped.

The coupling mechanism may consist of an outer magnetic cup with a multi-pole magnetisation pattern that coincides with the magnetic pattern on an inner magnet, or 2 similar multi-pole discs facing each other and separated by an intervening partition or membrane. Either magnet can act as the driver or driven element. As one magnet rotates relative to the other, the coupling experiences both an attractive force and repelling force as the driven magnet comes into line with the pole arrangement of the driving magnet. Both forces contribute to the overall torques of the coupling

Choose the right material

As each magnet experience a repelling force at some stage in the process, it is critical that the magnet material chosen should have a suitably high coercivity to resist the strong demagnetising forces. The combination of features such as isotropy, high coercivity and resistance to corrosion promotes the use of bonded magnets, both compression and injection moulded versions, in the use of magnetically driven pumps.

Such pumps are used in a variety of different applications ranging from automotive fuel pumps and cooling systems to drinks dispensers.