Manufacturing Process and Production
Ferrite magnets are made in a sintering and calcination process. This is a chemical reaction of the starting materials of iron oxide and barium or strontium. This process is called, using an outdated term, “pre-sintering”. The product is ground into a fine powder and then placed in molds for the drying and sintering process.
The magnetization process also occurs at this stage using an external magnetic field. The particles are carried in a preferred orientation (anisotropy). The so-called dry pressing method can also be used for the construction of small and simple geometric shapes.
These magnets have a constant magnetic field and they are called permanent magnets, which consist of a magnetizable piece of ferrite material.
Types Of Ferrite Magnets
The ferrite material is divided into two types, hard ferrite, and soft ferrite. Soft ferrite is characterized by a low coercivity, whereas hard ferrite has a very strong magnetic field and also has a high coercivity, meaning they are difficult to demagnetize.
Isotropic and Anisotropic
Advantages and disadvantages of Ferrite Magnets
A big advantage of these magnets is the high coercivity and high resistance. Another pro for these magnets is their low price and higher corrosion resistance compared to other magnets. Special surface treatment is not necessary.
Another great characteristic of these magnets is their particular resistance to high temperatures. They can be used at temperatures between -40 °C and +250 °C, this is due to the sintering process which is made at high temperatures. They also have a particular resistance to chemical agents.
The only disadvantage of these magnets is the strength of the magnetic field, which is not comparable to neodymium magnets or samarium-cobalt magnets.
Ferrite magnets are often referred to as Ceramic magnets. They also have two poles, Normally north on the one face and south on the other face (magnetized through the thickness)
They are black in color and are supplied uncoated. These magnets do not corrode and can be used outdoors or in wet conditions without any problems.
Ferrite magnets are the most produced in the world. Because of this fact, they are more affordable than Neodymium magnets and are also very popular for day-to-day applications.