Daido Steel and NHK Spring Jointly Develop Next-Generation Rotors for EV Drive Motors, Contributing to Diversified Needs
Daido Steel Co., Ltd. and NHK Spring Co., Ltd. have jointly developed next-generation rotors for electric vehicle drive motors, leveraging the features of heavy rare-earth-free hot-worked magnets to achieve both high output and improved recyclability. Promotion will begin around May 2026, aiming for early practical application.
📋 Article Processing Timeline
- 📰 Published: May 14, 2026 at 00:00
- 🔍 Collected: May 13, 2026 at 15:32
- 🤖 AI Analyzed: May 13, 2026 at 16:05 (33 min after Collected)
Daido Steel Co., Ltd. (Headquarters: Nagoya City, Representative Director and President: Tetsuya Shimizu), utilizing the features of heavy rare-earth-free hot-worked magnets, has jointly developed next-generation rotors with NHK Spring Co., Ltd. (Headquarters: Yokohama City, Representative Director and President: Kazuhisa Kamimura) that achieve both "higher output" and "improved recyclability" for electric vehicle*1 drive motors (Figures 1, 2).
In this development, by leveraging the unique technology of our heavy rare-earth-free hot-worked magnets, which offer a degree of freedom in shape and magnetization direction control that is difficult to achieve with commonly used sintered magnets, and by forming magnets in a shape close to their final use, we have expanded the design flexibility of rotors, which was difficult with conventional structures. We plan to start promotions around May 2026, aiming for early practical application.
This developed product will be exhibited for the first time at NHK Spring's booth at the "Human and Car Technology Exhibition 2026" held at Pacifico Yokohama from May 27 to 29, 2026, and at Aichi Sky Expo from June 17 to 19, 2026.
Figure 1. SPM Rotor (Cut Model) (Image courtesy of NHK Spring)
Figure 2. Spring-fixed IPM Rotor (Image courtesy of NHK Spring)
Figure 3. Hot-worked Magnet (Net Shape Magnet)
Figure 4. Hot-worked Magnet (Magnet with Groove Processing)
●Developed Product 1: High-output, High-speed SPM Rotor*2
From the perspective of curbing global warming, the electrification of mobility drive mechanisms is rapidly progressing. Amidst this trend, the demand for space-saving and cost reduction in drive motors is higher than ever. NHK Spring aimed to achieve miniaturization by increasing the output of SPM rotors to solve these challenges.
In this joint development, the selection of magnets was one of the major challenges. Generally, magnets used in SPM rotors are manufactured in block shapes and then machined into arc shapes for attachment to the rotor, which resulted in significant material loss. Therefore, we proposed heavy rare-earth-free hot-worked magnets (Figure 3), which offer high freedom in shape and magnetic circuit design and can be manufactured in a shape close to their final use. Furthermore, by combining this with NHK Spring's reinforcement technology using CFRP (Carbon Fiber Reinforced Plastic), we achieved high-speed rotation, realizing a structure that maximizes these features and led to this development.
This SPM rotor has higher motor output compared to conventional products. This product will contribute to the development of energy-efficient mobility through further miniaturization of drive motors.
Figure 5. Features of Hot-worked Magnets (High shape flexibility and variation in orientation direction, difficult to achieve with sintered magnets)
●Developed Product 2: Easily Disassemblable IPM Rotor
Generally, magnets used in IPM rotors*3 are fixed with resin in slots, requiring a heating process to remove the resin during recycling. This process emits a large amount of CO2, making the reduction of environmental impact a common challenge in the industry.
To solve this problem, NHK Spring focused on a new structure that fixes magnets with the force of leaf springs, aiming to realize a rotor from which magnets can be easily removed. However, installing leaf springs requires groove processing on the magnets, and the material loss generated during this process became a new problem.
Therefore, we proposed a unique technology that applies groove shapes during the hot forming process, which is the anisotropic process*4 of hot-worked magnets. This made it possible to manufacture magnets with grooves for leaf spring attachment without significantly changing the conventional process, while simultaneously achieving a significant reduction in material loss while maintaining production efficiency.
Figure 6. Magnet Fixing Structure of IPM Rotor (Image courtesy of NHK Spring)
Figure 7. Hot-worked Magnet with Leaf Spring Assembly (Image courtesy of NHK Spring)
Establishing this technology is expected to accelerate the development of IPM rotors with excellent recyclability and contribute to reducing the environmental impact of electric vehicle drive motors.
We will continue to pursue the potential of materials and support the future of people and society through co-creation with our customers.
End
●Exhibition Information for this Developed Product
Exhibition Name: Human and Car Technology Exhibition 2026 YOKOHAMA
Period: May 27 (Wed) - 29 (Fri), 2026, 10:00 - 17:00
Venue: Pacifico Yokohama Exhibition Hall North
Booth: NHK Spring (Nippon Hatsujo) Booth, Booth Number: 402
Exhibition Name: Human and Car Technology Exhibition 2026 NAGOYA
Period: June 17 (Wed) - 19 (Fri), 2026, 10:00 - 17:00
Venue: Aichi Sky Expo (Aichi International Exhibition Center)
In this development, by leveraging the unique technology of our heavy rare-earth-free hot-worked magnets, which offer a degree of freedom in shape and magnetization direction control that is difficult to achieve with commonly used sintered magnets, and by forming magnets in a shape close to their final use, we have expanded the design flexibility of rotors, which was difficult with conventional structures. We plan to start promotions around May 2026, aiming for early practical application.
This developed product will be exhibited for the first time at NHK Spring's booth at the "Human and Car Technology Exhibition 2026" held at Pacifico Yokohama from May 27 to 29, 2026, and at Aichi Sky Expo from June 17 to 19, 2026.
Figure 1. SPM Rotor (Cut Model) (Image courtesy of NHK Spring)
Figure 2. Spring-fixed IPM Rotor (Image courtesy of NHK Spring)
Figure 3. Hot-worked Magnet (Net Shape Magnet)
Figure 4. Hot-worked Magnet (Magnet with Groove Processing)
●Developed Product 1: High-output, High-speed SPM Rotor*2
From the perspective of curbing global warming, the electrification of mobility drive mechanisms is rapidly progressing. Amidst this trend, the demand for space-saving and cost reduction in drive motors is higher than ever. NHK Spring aimed to achieve miniaturization by increasing the output of SPM rotors to solve these challenges.
In this joint development, the selection of magnets was one of the major challenges. Generally, magnets used in SPM rotors are manufactured in block shapes and then machined into arc shapes for attachment to the rotor, which resulted in significant material loss. Therefore, we proposed heavy rare-earth-free hot-worked magnets (Figure 3), which offer high freedom in shape and magnetic circuit design and can be manufactured in a shape close to their final use. Furthermore, by combining this with NHK Spring's reinforcement technology using CFRP (Carbon Fiber Reinforced Plastic), we achieved high-speed rotation, realizing a structure that maximizes these features and led to this development.
This SPM rotor has higher motor output compared to conventional products. This product will contribute to the development of energy-efficient mobility through further miniaturization of drive motors.
Figure 5. Features of Hot-worked Magnets (High shape flexibility and variation in orientation direction, difficult to achieve with sintered magnets)
●Developed Product 2: Easily Disassemblable IPM Rotor
Generally, magnets used in IPM rotors*3 are fixed with resin in slots, requiring a heating process to remove the resin during recycling. This process emits a large amount of CO2, making the reduction of environmental impact a common challenge in the industry.
To solve this problem, NHK Spring focused on a new structure that fixes magnets with the force of leaf springs, aiming to realize a rotor from which magnets can be easily removed. However, installing leaf springs requires groove processing on the magnets, and the material loss generated during this process became a new problem.
Therefore, we proposed a unique technology that applies groove shapes during the hot forming process, which is the anisotropic process*4 of hot-worked magnets. This made it possible to manufacture magnets with grooves for leaf spring attachment without significantly changing the conventional process, while simultaneously achieving a significant reduction in material loss while maintaining production efficiency.
Figure 6. Magnet Fixing Structure of IPM Rotor (Image courtesy of NHK Spring)
Figure 7. Hot-worked Magnet with Leaf Spring Assembly (Image courtesy of NHK Spring)
Establishing this technology is expected to accelerate the development of IPM rotors with excellent recyclability and contribute to reducing the environmental impact of electric vehicle drive motors.
We will continue to pursue the potential of materials and support the future of people and society through co-creation with our customers.
End
●Exhibition Information for this Developed Product
Exhibition Name: Human and Car Technology Exhibition 2026 YOKOHAMA
Period: May 27 (Wed) - 29 (Fri), 2026, 10:00 - 17:00
Venue: Pacifico Yokohama Exhibition Hall North
Booth: NHK Spring (Nippon Hatsujo) Booth, Booth Number: 402
Exhibition Name: Human and Car Technology Exhibition 2026 NAGOYA
Period: June 17 (Wed) - 19 (Fri), 2026, 10:00 - 17:00
Venue: Aichi Sky Expo (Aichi International Exhibition Center)