What is the Magnetization Direction for Permanent Magnets?
Introduction
Magnetization direction is used to describe the direction of a magnetic pole in the magnet. The magnetization direction is determined before the magnet is magnetized. It is not something that is left to chance because it determines how the magnet is applied. To understand how a particular magnet is best applied, it is essential to study its magnetization direction.
Permanent magnets are magnets that, once magnetized, always retain their magnetism. Permanent magnets create their magnetic field. They do not depend on external sources such as electricity to generate their magnetic field. Hence, they are constantly magnetized.
Permanent magnets are usually made from ferromagnetic material. These materials are heated at extremely high temperatures. This makes the magnetic areas of the material align themselves in the same direction as the external magnetic field. After heating, the material is allowed to cool, and the aligned magnetic areas remain in a fixed position.
Isotropic and Anisotropic Magnets
Anisotropic Magnets
Anisotropic magnets are magnets that have their magnetic properties tightly tied to their magnetization direction. In essence, they have varying levels of magnetism in different magnetization directions. When magnetized, they are aligned in their future magnetization direction. These magnets have a preferred magnetization direction. Outside this direction, they cannot be magnetized. An advantage of this type of magnet is that it is stronger than isotropic magnets.
Isotropic Magnets
Isotropic magnets do not have their magnetic properties tightly tied to their magnetization direction. They have no preferred magnetization direction, and magnetization can occur in any direction. The magnetic force of isotropic magnets is usually in the direction of magnetization. During manufacture, isotropic magnets are not oriented in any direction. They usually have less magnetic strength than anisotropic magnets. However, they are less expensive than anisotropic magnets.
Magnetization Direction for Permanent Magnets
There are three major magnetization directions for permanent magnets.
Axial Magnetization Direction
Axial magnetization is directed along the length of the magnet. In axial magnetization, the magnet is magnetized along an axis. It is the most popular type of magnetization. If a cylindrical magnet has an axial magnetization direction, it implies that the magnetic poles will be located on the flat surface of the magnet. This means a magnet magnetized in this direction will be more efficient when the flat surface is near the material you want it to attract.
Diametrical Magnetization Direction
In contrast to axial magnetization direction, diametric magnetization direction occurs along the breadth or diameter of the magnet. In diametrical magnetization, the poles are on the curved side of the magnet if the magnet is cylindrical. This means the magnet will be more efficient if the curved side is near the material you want it to attract.
Radial Magnetization Direction
In radial magnetization, magnetization is directed along the outer and inner diameters of the magnet. It is usually used for ring-shaped magnets.
Magnetization Direction Testing
Ever wondered about the magnetization direction of a magnet? With this simple test, you can determine the magnetization direction of a magnet. When you place a ferromagnetic material close to a magnet, and you feel a strong pull at its flat end, then it is axially magnetized. If, however, the pull is stronger at the sides of the magnet, then the magnet is diametrically magnetized.
Types of Permanent Magnets and their Applications
From hard drives to televisions and transducers. Permanent magnets have many applications and types. The various types of permanent magnets can have any of the magnetization directions of permanent magnets described above.
Alnico
Alnico magnets are composed of aluminum, nickel, and cobalt. They may also include small quantities of copper and iron. These permanent magnets are usually highly resistant to corrosion. Also, they have high mechanical strength. Alnico magnets are most often anisotropic. Alnico magnets are used for microphones, electric motors, and sensors.
Ferrite
Ferrite magnets can be isotropic or anisotropic. They are made of compounds such as strontium oxide and iron trioxide. Occasionally, elements like cobalt and lanthanum are thrown into the mix. These magnets are often used in loudspeakers, medical instruments, and security systems.
Samarium Cobalt
Samarium Cobalt magnets are permanent magnets having a strong magnetic field. They are rare-earth magnets and are resistant to extreme changes in temperature. These magnets are most often anisotropic. Samarium cobalt magnets are usually used for generators, electric motors, and medical devices.
Neodymium Iron Boron
Neodymium Iron Boron Magnets have a preferred magnetic direction. They usually exhibit anisotropy. They can be magnetized axially, diametrically, or radially. Neodymium Iron Boron magnets are usually used in MRI scanners, dental instruments, jewelry, and medical devices.
Conclusion
It is important to understand the magnetization direction of permanent magnets. A clear understanding of the magnetization direction of permanent magnets serves as a guide on how best to apply the magnet. If you want to find more about permanent magnets, we would like to recommend you to visit Stanford Magents for more information.