Daido Steel Co. Ltd. and Honda Motor Co. Ltd. became the world’s first companies to achieve practical application of a hot, deformed neodymium magnet containing no heavy rare earth, but with high heat-resistance properties and high magnetic performance that hybrid vehicles require.
Neodymium magnets have the highest magnetic force among all magnets in the world and are being used for the drive motors of electric vehicles including hybrid vehicles, and therefore demand for neodymium magnets is expected to grow exponentially in the future. Adoption of this technology enables a break from the constraints associated with heavy rare earth, which had been one of the challenges to expanding the use of neodymium magnets.
This heavy rare earth-free hot deformed neodymium magnet will be applied first to the all-new Honda FREED, scheduled to go on sale this fall. For use in the drive motors of electric vehicles, neodymium magnets must have high heat-resistance properties for use in a high-temperature environment. Adding heavy rare earth (dysprosium and/or terbium) to the neodymium magnets has been a conventional method to secure such high heat resistance.
Daido Steel and Honda jointly developed new neodymium magnets while the former evolved its hot deformation technologies and the latter leveraged its experience in development of drive motors and revised the shape of the magnet. Through these joint development efforts, the two companies achieved, for the first time in the world (according to the companies’ press release) a practical application of a neodymium magnet that contains absolutely no heavy rare earth yet has high heat resistance and high magnetic performance suitable for use in the drive motor of hybrid vehicles.
Honda designed a new motor, which accommodates this new magnet. In addition to the shape of the magnet, the auto manufacturer revised the shape of the rotor to optimize the flow of the magnetic flux of the magnet. As a result, the hot, deformed neodymium magnet that contains absolutely no heavy rare earth became usable for the drive motor of a hybrid vehicle, demonstrating torque, output, and heat-resistance performance equivalent to those of a motor that uses the conventional type of magnet.