Magnetization Direction

The direction of magnetization is the first step to obtain magnetism in permanent magnet materials such as NdFeB and smco magnet. It represents the position of the north and south poles in a magnet or a magnetic assembly. The magnetic properties of permanent magnets are mainly derived from their easily magnetizable crystal structure. Because of this deconstruction, the magnet can obtain very high magnetic properties under the action of strong external magnetic field, and its magnetic properties will not disappear after the external magnetic field disappears.

From the perspective of magnetization direction, magnetic materials are divided into two categories: isotropic magnets and anisotropic magnets. As the name implies:

• Isotropic magnets have the same magnetic properties in any direction and can be attracted together arbitrarily.
• Anisotropic magnets have different magnetic properties in different directions, and the direction in which they can obtain the best/strongest magnetic properties is called the orientation direction of the magnet.

The orientation technology is a necessary process in the production of anisotropic magnets. Neo Magnet is anisotropic. The magnetic field orientation of the powder is one of the key technologies for manufacturing high performance NdFeB magnet. Sintered NdFeB is generally pressed with magnetic field orientation molding, so the orientation direction needs to be determined before production, which is the preferred magnetization direction. Once neodymium magnet is produced, the magnetization direction cannot be changed. If it is found that the wrong magnetization direction made, then the magnet needs to be customized again.

Axial magnetization and radial magnetization are usually used to indicate the direction of magnetization of cylinders/disc, rings, and arc shape magnets. With axially magnetized magnets, the magnetic force is mainly in the two end planes. With radially magnetized magnets, the magnetic field is mainly on the inner and outer arcs.

Magnetization is the process of applying a magnetic field to a permanent magnet in the direction of magnetic field orientation and gradually increasing the magnetic field strength to reach the technical saturation state.

Sintered NdFeB magnet can be made into many forms of square, cylinder, ring, segment, etc. Their magnetization direction is relatively simple, generally axial and radial magnetization.

Besides the simple magnetization direction, the sintered NdFeB ring can also be multi-pole magnetized according to the actual needs, i.e. multiple N and S poles can be presented on one plane after magnetization. Multi-pole ring needs to use specially designed magnetizing fixtures, so additional magnetizing fixture costs will be incurred.

Magnetizer is a tool for magnetizing magnetic materials or magnetic components. Through it, we can apply a magnetic field to the permanent magnet products that need to be magnetized.

The basic principle of magnetization is to place the magnetizable object to be magnetized in a magnetic field formed by a coil with direct current passing through it. There are two ways: direct current magnetization and pulse magnetization.

If the magnetization field does not reach the technical saturation field, the remanent magnetization Bj and coercivity Hcj of the permanent magnet will not reach their proper values. So how to determine the energy of the magnetizer?

Firstly, the size of the magnetizing tooling is determined according to the size of the magnetized product and the magnetizing direction. Then calculate the size of the magnetic field in the center of the tooling. The size of the magnetic field of the tooling should be 3-5 times the coercivity of the magnet. Then the magnetization current is calculated. Based on the current and the voltage of the magnetizer, the capacity of the magnetizer’s energy storage capacitor is finally determined. Finally, the energy of the magnetizer is determined.