Honda’s new hybrid motor magnet that’s free of heavy rare earth elements – new Freed to get it this year

Daido Steel and Honda are the world’s first companies to achieve practical application of a hot deformed neodymium magnet containing no heavy rare earth, and yet with high heat resistance properties and high magnetic performance required by a hybrid car’s motor.

This heavy rare earth-free hot deformed neodymium magnet will be debut in the new Honda Freed equipped with the company’s Sport Hybrid i-DCD (Intelligent Dual Clutch Drive) powertrain with Integrated Motor Assist later this year. The other engine for the new MPV is a regular 1.5L i-VTEC DOHC unit.

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 technology will make it possible to avoid resource-related risks and diversify channels of procurement.

Neodymium magnets have the highest magnetic force among all magnets, and are used in drive motors of EVs and hybrids. Neodymium magnets must have high heat resistance properties and adding heavy rare earth (dysprosium and/or terbium) to it has been a conventional method to ensure high heat resistance.

However, heavy earth elements, also known as rare metals, are found unevenly around the world, and the use of it carries risks from the perspectives of stable procurement and material costs. Therefore, this is a major breakthrough on Honda’s part.

Daido has been mass-producing neodymium magnets using the hot deformation method, which is different from the typical sintering production method. It enables nanometer-scale crystal grains to be well-aligned in order to realise a fine crystal grain structure that is around ten times smaller than that of a sintered magnet, which makes it possible to produce magnets with greater heat resistance properties.

For this new magnet, Daido further evolved its hot deformation tech and Honda leveraged its experience in development of drive motors and revised the shape of the magnet.

Honda also designed a new motor that accommodates the new magnet, revising the shape of the rotor to optimise the flow of the magnetic flux. Torque, output and heat resistance performance are equivalent to a motor that uses the conventional magnet type, Honda says.

With this new magnet, Daido will enter a market monopolised by sintered neodymium magnets. From next month, Daido will begin mass-production and shipment of this magnet using a new production line using a subsidy received from the Japanese government. Daido has been procuring magnetic powder (the raw material for magnets) from Canada’s Magnequench and will work with the latter to develop new types of raw magnetic powders for enhanced magnetic properties.

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