HOW MUCH MAGNETIZING FORCE DOES IT TAKE TO SATURATE MAGNETS?
- May 14, 2019-
To reach the maximum energy output of a magnet, it should be saturated, that is ,magnetized fully even though the magnet may be later stabilized either thermally or using a “knockdown” (or calibrating) field.
The magnetizing force required to saturate a magnet depends on the coercivity of the magnetic material and to a lesser extent, physical characteristics of the magnet and components to which it may be fastened during the magnetizing.
The general rule is that to saturate a magnet, one must apply a peak field of between 2 and 2.5 times the intrinsic coercivity. For example, an Hci of 20,000 oersteds will require at least 40,000 oersteds to saturate.
In the case of magnets attached to conductive fixtures, eddy currents are established in the material that set up a reverse magnetic field during the extremely short magnetizing pulse. This prevents the magnetizing flux from fully penetrating the conductor, perhaps even the magnet, and reduces the field the magnet sees and sometimes also the flux path (direction of the flux) in the magnet. In these cases, it is necessary for the equipment manufacturer to adjust the LC (inductance capacitance ratio) of the magnetizing circuit to extend the magnetizing pulse width. An extended pulse generates more heat which slows the production magnetizing rate. So a careful compromise must be reached.