Ferrite magnets may be either strontium ferrite (SrO.6Fe2O3) or barium ferrite (BaO.6Fe2O3) and can be produced with isotropic or anisotropic magnetic properties. Anisotropic properties are derived from the high magneto-crystalline shape anisotropy of the ferrite particles. These particles can be envisaged as hexagonal platelets with perpendicular magnetic preference (c – axis). Physical orientation of the ferrite particles is necessary in the pressing process to achieve magnetic alignment. Ferrite magnets have excellent corrosion resistance and have normal operating capabilities between - 40°C and +250°C. As temperature increases remanence decreases by 0.2 %/°C whereas coercivity increases by 0.3 %/°C. At very low temperatures there is a risk of permanent de-magnetisation in magnet systems with low working points.

PROCESSING
Processing begins with granulation or drying of the ferrite powder raw material before axial pressing to form compacts of the required shape.

Isotropic ferrite magnets are produced by dry pressing of granulated ferrite raw material using mechanical or hydraulic presses. Anisotropic magnet properties are achieved by pressing in a magnetic field. In this case, pressing may be carried out using dry powder or wet slurry dependent upon the level of anisotropic properties required. Specially designed electromagnetic tools are employed to produce the anisotropic grades. With all pressing techniques, continuous in-process monitoring techniques ensure consistent green density is maintained on all products.

After pressing the compacts are sintered in air at high temperature to consolidate them, thereby giving their definitive shape and strength.

Grinding and/or other finishing operations can be used to achieve very close dimensional tolerances if necessary.