Introduction
Bonded rare earth permanent magnets (REPM) are made from a combination of rare earth alloys and metal powders that are bonded together with organic or inorganic binder materials. The resulting magnet material is manufactured into shapes such as discs, rings, and blocks. Bonded REPM offer certain advantages over conventional sintered magnets, including improved magnetic properties and increased design flexibility.
History of Bonded Rare Earth Permanent Magnets
The history of bonded rare earth permanent magnets dates back to the mid 1960s when bonded NdFeB magnets were developed by Hitachi Metals Ltd. In Japan. Since then, bonded REPM have become increasingly popular as they offer several advantages over sintered REPM, such as superior energy density and better temperature stability.
Bonded REPM are typically composed of a combination of two or more different types of rare earth alloys and metal powders, which are then blended together with a binder to form a homogenous mixture. This mixture is pressed into the desired magnet shape and then heat-treated in order to harden and cure the bond between the components.
Advantages of Bonded Rare Earth Permanent Magnets
Bonded REPM offer a variety of advantages over conventional sintered magnets. The most significant advantage is the ability to customize a magnet to a specific geometry or shape. This allows for more efficient use of space in electronic devices and home appliances. Additionally, bonded REPM offer superior corrosion resistance and improved temperature stability when compared to sintered REPM. They also have higher energy density and are available in a greater range of sizes and shapes.
Processing of Bonded Rare Earth Permanent Magnets
Processing bonded REPM begins with the selection of the appropriate binder material. Typically, an organic binder is required in order to ensure the homogenous bonding of components. Once the binder is selected, all of the components are weighed and mixed, then pressed into the desired magnet shape. The pressed magnet is then heat-treated in order to harden and cure the bond. The heat-treating process typically takes several hours and results in a hardened, stable magnet.
Conclusion
Bonded REPM offer several advantages over conventional sintered REPM, including improved magnetic properties, higher energy density, and increased design flexibility. The processing of bonded REPM involves the selection of a binder material, followed by the weighing and mixing of components, and finally the pressing and heat-treating of the magnets. Despite the extensive processing, these magnets offer superior performance and are an attractive option for a variety of applications.
