Daido Steel and Honda Motor are the world’s first companies to achieve a practical application of a neodymium magnet containing no heavy rare earth elements. With high heat resistance and high magnetic performance required for the use in the driving motor electric motors, this appears to a breakthrough for hybrid vehicle design.
The problem with the currently used version of the neodymium magnet is that China is by far the largest producer of rare earth elements, universally used in electric motors in EVs and hybrids. However, China is thought to be a politically unstable, unreliable supplier. This is certainly with regards to Japan, which has ongoing disputes with the Communist nation that is now also part of the U.S. presidential debate.
The new Daido / Honda 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 – the first major since its 2008 introduction in Indonesia. The FREED is a compact minivan with two- or three-row seating that is well known in south east Asia but not the U.S. where the Fit ($18,000 and up) is sold. Obviously, there is a new hybrid version coming in Southeast Asia, the Honda SPORT HYBRID i-DCD, which will quickly spread to other nameplates. This hybrid system is scheduled to go on sale this fall in Japan.
Neodymium Magnets
Neodymium magnets have the highest magnetic force among all magnets in the world, which is why they are being used for the drive motors of electric vehicles and hybrids. Demand for neodymium magnets is expected to grow exponentially in the future.
For use in the drive motors of electric vehicles, neodymium magnets must have high heat resistance properties as they are used in a high temperature environment. Adding heavy rare earth – dysprosium and/or terbium – to neodymium magnets is the conventional method to secure heat resistance.
Daido Electronics – a wholly owned subsidiary of Daido Steel – has been mass-producing magnets using a hot deformation method, which is different from the typical sintering production method for neodymium magnets. Hot deformation enables nanometer-scale crystal grains to be well-aligned in order to produce a fine grain structure that is approximately ten times smaller than that of a sintered magnet, which makes it possible to produce magnets with greater heat resistance properties.
Daido Steel and Honda jointly developed the new neodymium magnets, while Daido Steel further evolved its hot deformation technologies and Honda used 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, a practical application of a neodymium magnet which contains zero heavy rare earth, yet has high heat resistance and high magnetic performance suitable for use in the drive motor of hybrid vehicles.
Moreover, Honda designed a new motor which accommodates this new magnet. In addition to the shape of the magnet, Honda 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.
