Can they truly replace traditional neodymium-iron-boron motors? What are their weaknesses and strengths in terms of magnetic energy product, cost, and demagnetization resistance? What obstacles are holding back their adoption in industrial motors and new energy vehicles? Let’s break it all down today!
I. The Core Showdown: Rare-Earth-Free vs. Neodymium-Iron-Boron Motors—A Comprehensive Analysis of Strengths and Weaknesses Across Three Dimensions
The core representatives of rare-earth-free permanent magnet motors are iron-nitrogen-based (such as samarium-iron-nitrogen) and aluminum-nickel-cobalt-based systems. Both differ significantly from traditional neodymium-iron-boron motors in terms of magnetic energy product (magnetic storage capacity), cost, and demagnetization resistance. See this table for a detailed comparison:
Performance/Cost Dimensions | Iron-Nitrogen-Based Rare-Earth-Free Motors | Aluminum-Nickel-Cobalt-Based Rare-Earth-Free Motors | Traditional Neodymium-Iron-Boron Motors |
Magnetic Energy Product (Magnetic Storage Core)
| Obvious disadvantages: While superior to ferrite, it is far inferior to neodymium-iron-boron and can only be used in low-end neodymium-iron-boron applications (where the energy product overlaps with that of low-end neodymium-iron-boron); it cannot meet the requirements for strong magnetic fields and small volumes. | Significant Weaknesses: The magnetic energy product is only 3–10 MGOe, far lower than the 20–60 MGOe of neodymium-iron-boron; it has a low magnetic storage capacity per unit volume, making it difficult to miniaturize motors.
| Overwhelming Advantages: It currently has the highest magnetic energy product among commercial permanent magnet materials, with a peak exceeding 60 MGOe; its high magnetic storage capacity per unit volume facilitates the miniaturization and weight reduction of motors. |
Cost (including supply chain)
| Significant Advantages: Samarium-iron-nitrogen costs approximately 130 yuan per kilogram, which is only one-third the price of neodymium-iron-boron (approximately 400 yuan per kilogram); it does not rely on rare earth elements, thereby avoiding the risk of rare earth price fluctuations | Competitive value: Raw materials are widely available and do not contain rare earth elements, ensuring strong cost stability; the manufacturing process is mature, resulting in low additional processing costs. | Higher costs: Relies on rare earth elements such as neodymium, and high-temperature optimization requires the addition of scarce elements like dysprosium and terbium, further driving up costs; fluctuations in the rare earth supply chain can easily lead to cost volatility. |
Demagnetization Resistance
| Polarization: Significant high-temperature advantages (Curie temperature of 470°C, far higher than the 310–400°C range for neodymium-iron-boron); however, it has low coercivity at room temperature, with coercivity decreasing by 0.5% for every 1°C increase in temperature, and dropping by approximately 40% at 100°C | Uneven Performance Across Temperature Ranges: Excellent high-temperature stability (Curie temperature of 700–860°C, remaining stable even at 500°C); however, low coercivity makes it susceptible to demagnetization from strong external magnetic fields
| Performs Well at Room Temperature: High coercivity at room temperature and strong resistance to demagnetization; high-temperature limitations (prone to irreversible demagnetization above 80°C), requiring special processes for optimization |
Key Conclusion: Rare-earth-free motors have the advantage of “stable costs and no reliance on rare earths,” but they are at a disadvantage due to “low magnetic energy product and weak resistance to demagnetization in certain applications”; neodymium-iron-boron motors excel in “high performance,” but are hampered by “high costs and reliance on rare earths.”
II. Application Bottlenecks: Why Is Widespread Adoption Difficult in Industrial Motors and New Energy Vehicles?
Although rare-earth-free motors offer cost advantages, their large-scale adoption in the two core sectors—industrial motors and new energy vehicles—still faces multiple bottlenecks, including both common challenges and sector-specific pain points:
1. Common Bottlenecks: Two Core Challenges Hinder Full-Scene Implementation
• Insufficient power density, at odds with the trend toward “miniaturization”: Low magnetic energy product implies “weak magnetic storage capacity.” To achieve the same power output as neodymium-iron-boron motors, the magnet volume and overall motor weight must be increased. However, current industrial motors prioritize “integration and miniaturization,” while new energy vehicles are extremely sensitive to “space utilization.” The “bulky and heavy” characteristics of rare-earth-free motors directly conflict with industry trends.
• Immature mass production processes and poor performance consistency: The manufacture of iron-nitrogen-based magnets suffers from “high-temperature decomposition,” requiring special processes such as low-temperature molding, which results in low production efficiency and difficulty in controlling yield rates; while aluminum-nickel-cobalt magnets have mature processing techniques, their magnetic performance exhibits significant variability during mass production. In contrast, mass production processes for neodymium-iron-boron magnets are already highly mature, and their consistent performance meets the demands of large-scale assembly.
• Insufficient adaptability in motor design: Existing motor control algorithms and structural designs are largely developed based on the characteristics of neodymium-iron-boron magnets, and adaptation solutions for rare-earth-free magnets—which have “low magnetic energy product and unique demagnetization resistance”—are still incomplete. For example, high-frequency operating conditions in industrial motors and scenarios involving strong magnetic fields during rapid acceleration in new energy vehicles all require redesigned optimization, resulting in high R&D costs and extended development cycles.
2. Sector-Specific Bottlenecks
(1) Industrial Motors: Difficulty in Meeting Stability Requirements
Industrial motors include fans, pumps, machine tools, and high-voltage, high-power motors. Operating conditions are complex and diverse, and the requirements for continuous operational stability are extremely high:
• Aluminum-nickel-cobalt-based motors are susceptible to demagnetization from strong external magnetic fields. In environments with strong electromagnetic interference—such as machine tools and large-scale equipment—sudden drops in the magnetic field may occur, leading to abnormal motor speed and torque and causing production failures;
• Iron-nitrogen-based motors exhibit poor performance consistency during mass production. However, large-scale assembly of industrial motors requires uniform standards; significant performance variability increases the difficulty and cost of operation and maintenance;
• Some high-voltage, high-power industrial motors require long-term operation at high temperatures. Although iron-nitrogen and Al-Ni-Co motors exhibit good high-temperature stability, their insufficient magnetic energy product results in oversized motors that are difficult to fit into the installation spaces of existing equipment.
(2) New Energy Vehicle Sector: Dual Bottlenecks of Range and Power
New energy vehicles impose stringent requirements on motors in terms of “power density, efficiency, and reliability,” which greatly magnifies the shortcomings of rare-earth-free motors:
• The conflict between range and space: Rare-earth-free motors tend to be bulky, crowding out battery installation space (battery capacity directly affects range); simultaneously, low magnetic energy product results in lower energy conversion efficiency, leading to weaker power output for the same battery capacity and further shortening the driving range—which directly conflicts with consumers’ demand for “long range and spacious interiors.”
• Insufficient reliability under extreme operating conditions: New energy vehicles generate strong alternating magnetic fields during rapid acceleration and long uphill climbs, causing motor temperatures to rise rapidly. Under these conditions, the coercive force of iron-nitrogen-based magnets drops significantly, while aluminum-nickel-cobalt magnets are prone to demagnetization by external magnetic fields—both of which can lead to a loss of power output and pose safety risks. In contrast, neodymium-iron-boron motors, after process optimization, can now reliably handle such extreme operating conditions.
• High retrofitting costs for automakers: The existing motor production lines and supply chains of leading automakers are all designed for neodymium-iron-boron magnets. Switching to rare-earth-free magnets would require rebuilding production lines and optimizing motor controller algorithms, entailing massive upfront investments that would be difficult to recoup in the short term.
III. Conclusion: A Path Forward for Rare-Earth-Free Motors
To overcome bottlenecks in the industrial motor and new energy vehicle sectors, efforts must focus on three areas: First, enhancing the performance of magnetic materials by optimizing material formulations and refining manufacturing processes to increase the magnetic energy product and room-temperature coercive force of iron-nitrogen-based magnets; second, optimizing motor design by developing high-efficiency topologies and control algorithms tailored to rare-earth-free magnetic materials; and third, reducing mass production costs by overcoming specific manufacturing challenges and improving production capacity and performance consistency.
