This section provides an overview for bonded magnets as well as their applications and principles. Also, please take a look at the list of 19 bonded magnet manufacturers and their company rankings.
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Bonded magnet is a generic term for magnets that are processed and molded by kneading fine-grained magnets into rubber or plastic.
Regular ferrite magnets are used as door seals for refrigerators and showcases or as whiteboards by making them into boards and processing their surfaces with plastics.
Rare earth magnets with high magnetic force, such as neodymium magnets, are molded into various shapes and used in industrial applications such as small motors, electronic components, and train drive motors.
Bonded magnets can be freely designed, manufactured, processed, and molded after production.
Ferrite magnets are easily used in daily life as magnetic tape and magnetic sheets and are also used for refrigerator doors and whiteboards.
Magnets with high magnetic force, such as neodymium magnets and samarium iron nitride magnets, are incorporated into small motors, used in hard disks, and are also used in drive motors for automobiles, trains, and elevators.
Permanent magnets currently in industrial use are classified into a cast, sintered, and bonded magnets.
Bonded magnets (polymer bonded magnets) are manufactured from magnet compounds made by kneading and dispersing a high concentration of fine powder (magnetic powder) of ferrite magnets or rare earth magnets in a binder such as a polymer resin or rubber.
After manufacturing, they can be processed and molded into complex structures with high precision. They not only have excellent mechanical properties, such as resistance to cracking and chipping but can also be easily integrated with thin, long, and wide metal, which is impossible with cast or sintered magnets.
It can be mass-produced and has many advantages as an industrial material.
In particular, using rare earth magnets with high magnetic force is indispensable for small motors and electronic components widely used today. Further miniaturization and efficiency can be achieved by improving the performance of the bonded magnet itself.
Rare earth-bonded magnets are also helpful in making generators smaller and more powerful, and their use in the energy generation field is expected to expand in the future.
Bonded magnets are made by solidifying magnetic powder with resin. On the other hand, sintered magnets are made by pressing magnetic powder and baking it at high temperatures.
In terms of magnetic properties and heat resistance, sintered magnets are superior to bonded magnets made by mixing resin. This is because the resin mixed in bonded magnets is a non-magnetic substance.
However, regarding dimensional accuracy, bonded magnets are superior because they are capable of more complex processing. This is because sintered magnets are subject to more significant sintering shrinkage during the manufacturing process.
Today, as environmental issues become more serious, the market for motors is also changing dramatically. Motors are used in various settings, including automobiles and home appliances, accounting for a large percentage of total power consumption in Japan. Saving electricity for motors is a critical issue for realizing a low-carbon society.
Against this backdrop, demand for PM motors is increasing.
PM motors with permanent magnets are more energy-efficient and efficient than non-permanent magnet motors (e.g., induction motors) because PM motors use permanent magnets in the rotor. This is because PM motors do not generate losses in the rotor. After all, the secondary current does not flow in the rotor.
PM motors are divided into two types according to the structure of the rotor: SPM motors and IPM motors. SPM motors have permanent magnets "stuck" to the rotor, and IPM motors have permanent magnets "embedded" in the rotor. IPM motors, with embedded magnets, can have higher speeds and increased mechanical safety.
Rare earth magnets with strong magnetic force support the technology of these PM motors. Still, rare earth magnets have been pointed out as a procurement risk due to soaring prices and unstable supply due to export restrictions in China and other factors.
In recent years, however, new technologies have been developed, such as the invention of IPM motors that utilize bonded magnets made from samarium, which are not rare earth magnets. Bonded magnets support the evolution of motors.
*Including some distributors, etc.
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