Manufacturing Process of Ferrite Magnet

The flow chart of ferrite magnets

Weighing & Mixing

The raw material of ferrite includes main raw material, additives and flux agents. Fe₂O₃, BaCO₃, SrCO₃ and CaCO₃ are main raw material of ferrite. The weighing process need to follow the formula strictly, or cannot get the desirable magnetic properties. The raw material will be mixed in specialized equipment after weighing process. The component homogeneity bases on mixing process. There are several factors affect the component homogeneity of mixture.

Pelletizing

In order to ensure the solid-phase reaction process, the mixtures need to pelletize before pre-sintering. The solution will spray to mixture during pelletizing process. The size of pellet material will influence the pre-sintering time.

Pre-sintering

The purpose of pre-sintering is fully guaranteeing the solid-phase reaction of raw material, and most of raw material will turn into ferrite phase after pre-sintering. The pre-sintering process will also improve deformation, shrinking and density. The pre-sintered powder can be used as the raw material of sintered magnet, bonded magnet and absorbing material. Most of ferrite manufacturers purchase pre-sintered powder directly now.

Crushing

The pre-sintered material will crush into fine powder in this step. The crushing process will be finished by ball mill equipment. The milling medium is steel ball and water.

Moulding

The ferrite magnets can be divided into isotropic and anisotropic base on traditional classification method. The ferrite also fall into wet process and dry process by theirs moulding mode. The technology intensive of moulding process is very high.

Sintering

Like other types of sintered magnet, the sintering step also very important for ferrite magnets. Firstly, the sintering process will affect the microstructure, and further influence the magnetic properties of ferrite. The unreasonable sintering parameters will cause magnet cracks, bubble and deformation.

Machining

The machining method of ferrite magnet contains grinding, polishing, cutting and punching. It is worth mentioning that the ferrite is insulating materials, so the manufacturer will use grinding wheel in cutting step.