Orientation and magnetization direction of magnetic steel

The magnetization direction depends on the orientation direction

Determine the easy magnetization direction based on the orientation direction, and only along the easy magnetization direction can the magnet reach saturation with minimal energy. What is orientation? Orientation is actually magnetization, but during the production and forming process of magnetic steel, pre magnetization is carried out on the magnetic powder that has not been finally densified or on the alloy that has not yet formed a phase during heat treatment, so that the magnetic domains are arranged as uniformly as possible along the direction of the magnetization field. The higher the arrangement, the better the orientation, and the higher the residual magnetism of the final magnet. Orientation can be simply regarded as road construction, similar to laying a north-south highway. Vehicles can only travel south or north and cannot travel in other directions. The magnetic domains after orientation can also be arranged in both directions, that is, if they are oriented vertically, they can only be magnetized in the vertical direction, which can be up N and down S, or up S and down N. According to whether there is an orientation stage in the production process of magnetic steel, permanent magnet materials can be divided into two categories, among which those with orientation are called anisotropic materials (also known as anisotropy), and those without orientation are called isotropic materials (also known as isotropy). The magnetic properties of anisotropic materials are stronger than those of isotropic materials. The residual magnetism of isotropic materials can only reach up to half of anisotropy, and the magnetic energy product can only reach up to a quarter of anisotropy. However, the intrinsic coercivity of isotropy is higher than that of anisotropy, and the demagnetization curve of anisotropy has better squareness, while the squareness of isotropy is poorer. Different types of magnets also have slight differences in orientation, with the most mainstream being magnetic field orientation, which means that during the molding or heat treatment process, a strong magnetic field (usually above 1.5T) is applied to make most of the C-axis of single domain particles turn in the same direction to achieve the effect of orientation. In addition to magnetic field orientation, there are also thermal deformation orientation and pressure orientation methods developed by utilizing the shape anisotropy of some magnetic domains.

For anisotropic magnetic steel, due to the ordered arrangement of magnetic domains after orientation, magnetization must be on the same axis or dimension as the orientation direction, as shown in the following figure. For highly oriented magnetic steel, magnetization can be done in a combination of up N and down S or up S and down N.

Isotropic magnets are not oriented, meaning their magnetic domains are arranged in a disordered manner. Although their performance is not high, they can be magnetized in all directions depending on the type of magnetic field applied. Therefore, just like a large number of isotropic bonded neodymium iron boron rings made into radiation multipole rings, any magnetization method that can be made by a magnetization fixture can magnetize the magnet, as shown in the following figure.