Beyond Rare Earths

Design, Prototyping and Testing of High-Performance Electric Motors using Rare-Earth-Free Iron Nitride Magnets

A few years ago, the term rare earths was virtually unknown outside of specialist fields. Today, it has become central to global discussions across industry, technology and geopolitics.

Rare earth elements, particularly heavy rare earth elements (HREEs), play a critical role in modern electric motor design.

Five elements are especially important:

• Neodymium (Nd)
• Samarium (Sm)
• Dysprosium (Dy)
• Terbium (Tb)
• Holmium (Ho)

Over the past four decades, these materials have been instrumental in the evolution of high-performance electric motors.

From Conventional Materials to Advanced Magnets

In the 1960s, electric motors were manufactured using widely available materials such as iron, copper, and aluminum, with only limited use of ferrite magnets. At that time, power density was limited to approximately 100–200 kW per ton.

The first major technological leap came with the introduction of Samarium Cobalt (SmCo) magnets, which offered up to ten times higher energy density than previous solutions.

A second major advance followed in the 1980s with the development of Neodymium Iron Boron (NdFeB) magnets, enabling even greater performance gains. This advancement dramatically increased motor power density to several thousand kW per ton while reducing size, weight, and material consumption.

The Role of Heavy Rare Earth Elements

Further performance improvements were achieved by adding HREEs such as Dysprosium, Terbium and Holmium. This allowed power density to exceed 5,000 kW per ton, enabling extremely compact and powerful systems.

As a result, Permanent Magnet Synchronous Motors (PMSM) rapidly gained market share, particularly in automotive and robotics, and gradually replaced traditional induction motors in many industrial applications.

Spin’s Approach: Rare-Earth-Free Solutions

For more than 25 years, Spin has worked to reduce dependency on rare earth materials.

The company has developed a complete range of synchronous reluctance motors that are fully free of permanent magnets, currently covering applications from 2 kW to 31 kW, with further developments underway up to 100 kW.

Iron Nitride Magnets: A Sustainable Alternative

To complement this approach, Spin collaborated with Niron Magnetics to explore the next generation of magnets: rare-earth-free Iron Nitride magnets. Iron Nitride magnets are made from widely available materials, and no rare earths or critical minerals.

Although their energy product (BHmax) is lower than traditional NdFeB magnets at room temperature, this parameter alone does not determine real motor performance.

NdFeB magnets exhibit significant degradation at elevated temperatures, while Iron Nitride magnets maintain performance properties.

This narrows the performance gap under real operating conditions.

Design Strategy, Optimization, Concept and Validation

Spin adopted a comprehensive design methodology focused on magnetic performance, electrical efficiency, thermal behavior,
and mechanical robustness.

The company supports the full development process, including magnet evaluation and testing, motor design and optimization, prototype manufacturing, and experimental validation. All testing activities are performed in Spin’s laboratory in Ravenna, ensuring full control over performance verification.

Electric Motors with Iron Nitride Magnets

Niron’s Iron Nitride magnets represent a promising step toward sustainable, resilient, and high-performance electric motor technologies.

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