Magnets, Rare Earth Metals, and the Supply Chain Risks Ahead
Nov 22, 2024
Introduction
In electric motors, magnetic components are what create the consistent magnetic fields necessary for efficient electro-mechanical energy conversion, forming the backbone of countless industrial, commercial, and consumer applications.
The optimization of magnetic materials for specific motor designs involves intricate trade-offs between magnetic field strength, temperature stability, coercivity, and cost. These considerations become particularly significant as motors are pushed to higher power densities and operating temperatures, demanding ever more sophisticated magnetic materials.
Today's electric motors predominantly rely on rare-earth permanent magnets, specifically neodymium-iron-boron (NdFeB) compositions, due to their superior magnetic properties. However, this technological advantage comes with significant supply chain vulnerabilities and environmental considerations that are reshaping how the industry approaches magnet selection and motor design.
In this article, we'll walk through the fundamental principles of electric motor operation, explore some of the properties that make neodymium magnets dominant in the field, and analyze current supply chain dynamics. We'll then explore some emerging alternatives like Iron Nitride and other magnetic compounds that could reshape the future of electric motor design. While many of these research areas have long ways to go, they can unlock critical capabilities for US domestic supply chains that support countless industries!
High-level Motor Background
The fundamental operation of brushless permanent magnet (PM) motors centers on the interaction between permanent magnets mounted on the rotor and electrical windings on the stator. This configuration creates two distinct types of torque: detent torque and mutual (or alignment) torque.
Detent torque occurs naturally due to the magnetic interaction between rotor magnets and the stator's steel structure. At certain positions called detent positions, this torque becomes zero. These positions can be either stable (when magnets align with stator poles) or unstable (halfway between poles). While the theoretical shape of detent torque is sinusoidal, real-world factors like geometry and material properties create more complex patterns.
The primary working principle of the motor relies on mutual torque, created when current flows through the stator windings. When energized, these windings become electromagnets, producing a force of attraction between opposite magnetic poles of the stator and rotor. This mutual attraction generates the alignment torque that drives the motor's rotation.
To achieve continuous rotation, motors typically employ multiple phase windings. While it's technically possible to construct a brushless PM motor with any even number of rotor magnet poles and any number of phases, two and three-phase designs dominate the industry. This preference stems from the practical consideration of minimizing the required power electronic components for current control.
A few high level design notes:
The stator construction features several key elements:
Protruding teeth directed toward the rotor magnets
A steel outer ring called the stator yoke or back iron
Slots between teeth that house the windings
Either concentrated windings (isolated around individual poles) or more commonly, distributed windings where phases overlap
The rotor structure includes:
Permanent magnets arranged with alternating polarities
An inner steel ring (rotor yoke or back-iron) supporting the magnets
The choice of magnet pole count involves a few important trade-offs:
Higher pole counts generally increase torque production efficiency
However, more poles require faster power electronics switching
At higher speeds, fewer poles are often chosen to reduce power electronics costs
This creates a balance between torque production efficiency and total system cost
Permanent Magnets and Neodymium
Electric motors rely on permanent magnets to create the strong, consistent magnetic fields needed for energy conversion. While various magnetic materials have been used throughout history - from basic ferrite to specialty alloys - modern high-performance motors overwhelmingly use rare-earth magnets.
Neodymium-iron-boron (NdFeB) magnets dominate today's motor designs due to their exceptional magnetic properties. These rare-earth magnets provide the highest energy product (BHmax) of any permanent magnet material commercially available, enabling motors with superior power density and efficiency.
Key performance advantages include:
High magnetic field strength (flux density)
Strong resistance to demagnetization (coercivity)
Excellent performance-to-weight ratio
Reliable operation at typical motor temperatures
The primary technical challenge with NdFeB magnets is their temperature sensitivity. Performance degrades as temperature increases, with irreversible demagnetization possible above their maximum operating temperature (typically 150°C). Motor designers must carefully consider thermal management to maintain magnet performance.
The material's supply chain presents significant strategic challenges. China controls approximately 90% of global rare earth production and processing (as of 2024), creating potential vulnerabilities in the manufacturing pipeline. This concentration of supply, combined with growing demand across industries, along with trade tensions, drives both cost volatility and concerns about long-term availability.
The Supply Chain Challenge
A significant disruption in China's rare earth supply will severely impact global motor manufacturing. Many producers or consumers that have their supply chains run through Europe believe they’re safe from these effects, but that’s absolutely not true. This supply chain is massively interconnected, and a disruption this large is going to cause shortages for everyone. The immediate effects would include:
Sharp price increases for existing magnet stockpiles
Production slowdowns or stoppages in motor manufacturing
Emergency sourcing from limited alternative suppliers in Australia, Malaysia, and California
Long-term impacts:
Accelerated development of alternative motor designs using different magnetic materials
Rapid scaling of rare earth mining and processing in other regions
Increased investment in recycling technologies for recovering neodymium from existing motors
While some manufacturers maintain strategic reserves, these typically only cover months of production. The timeline for developing new supply chains outside China spans years, not months, due to the complex processing requirements and environmental regulations. This vulnerability has already prompted some manufacturers to explore alternative motor designs and magnetic materials, leading into our next discussion of emerging alternatives.
Emerging Alternatives
Iron Nitride (Fe16N2) stands as one of the most promising alternatives to rare earth magnets. Its theoretical magnetic properties approach those of neodymium magnets, while using earth-abundant materials. Current challenges include manufacturing scale-up and maintaining magnetic properties at motor operating temperatures.
Alternative Magnetic Materials:
Ferrite Magnets
Lower cost and widely available
Significantly weaker magnetic properties
Better temperature stability than NdFeB
Already used in lower-performance applications
Samarium Cobalt
Strong magnetic properties
Excellent temperature resistance
High cost and limited cobalt supply
Used in high-temperature applications
Novel Research Directions:
Nanostructured magnetic materials
Enhanced ferrite compositions
Hybrid designs using multiple magnetic materials
Reduced-rare-earth magnet compositions
Each alternative presents trade-offs between performance, cost, and manufacturability. While none currently match neodymium's combination of strength and practicality, ongoing research and development could change this balance, particularly as supply chain pressures increase, and there’s no greater pressure to innovate than necessity.
Wrapping It All Up
The electric motor industry faces a critical junction between proven technology and future necessity. While neodymium magnets remain superior in performance, their concentrated supply chain creates substantial risks for manufacturers globally. This vulnerability, combined with growing demand for electric motors, makes the development of alternative magnetic materials increasingly urgent.
Progress in alternatives like Iron Nitride and enhanced ferrite materials shows promise, but significant engineering challenges remain. The path forward likely involves parallel approaches: developing new supply chains outside China, advancing alternative magnetic materials, and optimizing motor designs to reduce rare earth dependency.
The future of electric motor technology will be shaped by how successfully we navigate these challenges, balancing performance requirements with material availability and sustainability.
What’s our role?
Ethereal specializes in the design and manufacturing of low-cost, reliable, and high-volume electric actuators to serve robotics, drone, and industrial automation companies.
We are exploring all avenues to secure the supply chain to ensure fast and reliable access to electric motors for the western world in the potentially turbulent years ahead.
If you are interested in partnering with us to develop US-resilience in the motor supply chain, please reach out!
References:
Hanselman, D. (2006). Brushless Permanent Magnet Motor Design (2nd ed.). Magna Physics Publishing.
S&P Global Commodity Insights. (2024, February 7). China boosts quota for first batch of rare earth production in 2024. S&P Global. (https://www.spglobal.com/commodityinsights/en/market-insights/latest-news/metals/020724-china-boosts-quota-for-first-batch-of-rare-earth-production-in-2024)
Wang, J.-P. (2019). Environment-friendly bulk Fe$${16}$$N$${2}$$ permanent magnet: Review and prospective. Journal of Magnetism and Magnetic Materials, 497, 165962. https://doi.org/10.1016/j.jmmm.2019.165962
Magnets, Rare Earth Metals, and the Supply Chain Risks Ahead
Nov 22, 2024
Introduction
In electric motors, magnetic components are what create the consistent magnetic fields necessary for efficient electro-mechanical energy conversion, forming the backbone of countless industrial, commercial, and consumer applications.
The optimization of magnetic materials for specific motor designs involves intricate trade-offs between magnetic field strength, temperature stability, coercivity, and cost. These considerations become particularly significant as motors are pushed to higher power densities and operating temperatures, demanding ever more sophisticated magnetic materials.
Today's electric motors predominantly rely on rare-earth permanent magnets, specifically neodymium-iron-boron (NdFeB) compositions, due to their superior magnetic properties. However, this technological advantage comes with significant supply chain vulnerabilities and environmental considerations that are reshaping how the industry approaches magnet selection and motor design.
In this article, we'll walk through the fundamental principles of electric motor operation, explore some of the properties that make neodymium magnets dominant in the field, and analyze current supply chain dynamics. We'll then explore some emerging alternatives like Iron Nitride and other magnetic compounds that could reshape the future of electric motor design. While many of these research areas have long ways to go, they can unlock critical capabilities for US domestic supply chains that support countless industries!
High-level Motor Background
The fundamental operation of brushless permanent magnet (PM) motors centers on the interaction between permanent magnets mounted on the rotor and electrical windings on the stator. This configuration creates two distinct types of torque: detent torque and mutual (or alignment) torque.
Detent torque occurs naturally due to the magnetic interaction between rotor magnets and the stator's steel structure. At certain positions called detent positions, this torque becomes zero. These positions can be either stable (when magnets align with stator poles) or unstable (halfway between poles). While the theoretical shape of detent torque is sinusoidal, real-world factors like geometry and material properties create more complex patterns.
The primary working principle of the motor relies on mutual torque, created when current flows through the stator windings. When energized, these windings become electromagnets, producing a force of attraction between opposite magnetic poles of the stator and rotor. This mutual attraction generates the alignment torque that drives the motor's rotation.
To achieve continuous rotation, motors typically employ multiple phase windings. While it's technically possible to construct a brushless PM motor with any even number of rotor magnet poles and any number of phases, two and three-phase designs dominate the industry. This preference stems from the practical consideration of minimizing the required power electronic components for current control.
A few high level design notes:
The stator construction features several key elements:
Protruding teeth directed toward the rotor magnets
A steel outer ring called the stator yoke or back iron
Slots between teeth that house the windings
Either concentrated windings (isolated around individual poles) or more commonly, distributed windings where phases overlap
The rotor structure includes:
Permanent magnets arranged with alternating polarities
An inner steel ring (rotor yoke or back-iron) supporting the magnets
The choice of magnet pole count involves a few important trade-offs:
Higher pole counts generally increase torque production efficiency
However, more poles require faster power electronics switching
At higher speeds, fewer poles are often chosen to reduce power electronics costs
This creates a balance between torque production efficiency and total system cost
Permanent Magnets and Neodymium
Electric motors rely on permanent magnets to create the strong, consistent magnetic fields needed for energy conversion. While various magnetic materials have been used throughout history - from basic ferrite to specialty alloys - modern high-performance motors overwhelmingly use rare-earth magnets.
Neodymium-iron-boron (NdFeB) magnets dominate today's motor designs due to their exceptional magnetic properties. These rare-earth magnets provide the highest energy product (BHmax) of any permanent magnet material commercially available, enabling motors with superior power density and efficiency.
Key performance advantages include:
High magnetic field strength (flux density)
Strong resistance to demagnetization (coercivity)
Excellent performance-to-weight ratio
Reliable operation at typical motor temperatures
The primary technical challenge with NdFeB magnets is their temperature sensitivity. Performance degrades as temperature increases, with irreversible demagnetization possible above their maximum operating temperature (typically 150°C). Motor designers must carefully consider thermal management to maintain magnet performance.
The material's supply chain presents significant strategic challenges. China controls approximately 90% of global rare earth production and processing (as of 2024), creating potential vulnerabilities in the manufacturing pipeline. This concentration of supply, combined with growing demand across industries, along with trade tensions, drives both cost volatility and concerns about long-term availability.
The Supply Chain Challenge
A significant disruption in China's rare earth supply will severely impact global motor manufacturing. Many producers or consumers that have their supply chains run through Europe believe they’re safe from these effects, but that’s absolutely not true. This supply chain is massively interconnected, and a disruption this large is going to cause shortages for everyone. The immediate effects would include:
Sharp price increases for existing magnet stockpiles
Production slowdowns or stoppages in motor manufacturing
Emergency sourcing from limited alternative suppliers in Australia, Malaysia, and California
Long-term impacts:
Accelerated development of alternative motor designs using different magnetic materials
Rapid scaling of rare earth mining and processing in other regions
Increased investment in recycling technologies for recovering neodymium from existing motors
While some manufacturers maintain strategic reserves, these typically only cover months of production. The timeline for developing new supply chains outside China spans years, not months, due to the complex processing requirements and environmental regulations. This vulnerability has already prompted some manufacturers to explore alternative motor designs and magnetic materials, leading into our next discussion of emerging alternatives.
Emerging Alternatives
Iron Nitride (Fe16N2) stands as one of the most promising alternatives to rare earth magnets. Its theoretical magnetic properties approach those of neodymium magnets, while using earth-abundant materials. Current challenges include manufacturing scale-up and maintaining magnetic properties at motor operating temperatures.
Alternative Magnetic Materials:
Ferrite Magnets
Lower cost and widely available
Significantly weaker magnetic properties
Better temperature stability than NdFeB
Already used in lower-performance applications
Samarium Cobalt
Strong magnetic properties
Excellent temperature resistance
High cost and limited cobalt supply
Used in high-temperature applications
Novel Research Directions:
Nanostructured magnetic materials
Enhanced ferrite compositions
Hybrid designs using multiple magnetic materials
Reduced-rare-earth magnet compositions
Each alternative presents trade-offs between performance, cost, and manufacturability. While none currently match neodymium's combination of strength and practicality, ongoing research and development could change this balance, particularly as supply chain pressures increase, and there’s no greater pressure to innovate than necessity.
Wrapping It All Up
The electric motor industry faces a critical junction between proven technology and future necessity. While neodymium magnets remain superior in performance, their concentrated supply chain creates substantial risks for manufacturers globally. This vulnerability, combined with growing demand for electric motors, makes the development of alternative magnetic materials increasingly urgent.
Progress in alternatives like Iron Nitride and enhanced ferrite materials shows promise, but significant engineering challenges remain. The path forward likely involves parallel approaches: developing new supply chains outside China, advancing alternative magnetic materials, and optimizing motor designs to reduce rare earth dependency.
The future of electric motor technology will be shaped by how successfully we navigate these challenges, balancing performance requirements with material availability and sustainability.
What’s our role?
Ethereal specializes in the design and manufacturing of low-cost, reliable, and high-volume electric actuators to serve robotics, drone, and industrial automation companies.
We are exploring all avenues to secure the supply chain to ensure fast and reliable access to electric motors for the western world in the potentially turbulent years ahead.
If you are interested in partnering with us to develop US-resilience in the motor supply chain, please reach out!
References:
Hanselman, D. (2006). Brushless Permanent Magnet Motor Design (2nd ed.). Magna Physics Publishing.
S&P Global Commodity Insights. (2024, February 7). China boosts quota for first batch of rare earth production in 2024. S&P Global. (https://www.spglobal.com/commodityinsights/en/market-insights/latest-news/metals/020724-china-boosts-quota-for-first-batch-of-rare-earth-production-in-2024)
Wang, J.-P. (2019). Environment-friendly bulk Fe$${16}$$N$${2}$$ permanent magnet: Review and prospective. Journal of Magnetism and Magnetic Materials, 497, 165962. https://doi.org/10.1016/j.jmmm.2019.165962