The field strength required for full magnetisation (to saturation) varies with the mineral of the magnet. These figures show the necessary field strengths for the various materials.
The curves are typical of the material groups, based on experimental values, and show the field strength for the initial magnetisation (initial curve). Altering the magnetisation or remagnetising components that have been demagnetised in alternation fields require considerably higher field strengths.
As a rough estimate for the magnetisation of hard ferrite magnets, the triple coercitivity HCJ has to be applied.
Bonded hard ferrite magnets and bonded SMCo magnets require the same magnetising field strength as sintered magnets of the same materials. Bonded NdFeB magnetes require slightly stronger magnetising fields than sintered NdFeB magnets.
SmCo magnets require the highest magnetising field strengths.
For These magnets, magnetising multiple poles is very difficult.
The magnetising field strength for NdFeB magnets depends on the coercitivity. NdFeB magnets with high coercitivity are easier to magnetise those with low coercitivity (high remanence).