Axial Flux Motor Rotor Cost Breakdown: Magnets, Iron Core, Or Encapsulation – Which Takes The Biggest Share?

xial flux motors are driving a power revolution in new energy vehicles, humanoid robots, eVTOL (electric vertical take-off and landing) aircraft, and more, thanks to their compact size, light weight, and high power density. However, the relatively high manufacturing cost remains a bottleneck for large scale adoption. So, what exactly makes up the cost of an axial flux motor rotor? And among magnet grade, core lamination process, and encapsulation material, which one accounts for the largest portion? This article breaks it down for you.

1. Magnet Grade – The Undisputed Cost Champion

Among all materials in an axial flux motor, magnets (permanent magnets) are the largest cost item.

The high-performance neodymium-iron-boron (NdFeB) magnets embedded in the rotor disc are the “heart” that generates the magnetic field. Because axial flux motor rotors are typically ultra-thin and can operate at temperatures of 180-200°C, the magnets must exhibit extremely high energy product, high coercivity (to resist demagnetisation), and the ability to be processed into micron-thin slices. Standard NdFeB magnets cannot meet these stringent requirements – specially customised high-grade materials are essential.

Industry data shows that magnets account for 35-40% of the total motor cost, and dominate the rotor material cost even more decisively. With rising rare-earth material prices in recent years, this share is trending even higher. Therefore, the magnet grade is the number-one factor determining rotor cost.

2. Core Lamination – Smaller Cost Share, but Not Without Technical Challenges

The iron core (including the stator core and part of the rotor back-iron) accounts for a relatively smaller portion of the axial flux motor cost.

Unlike traditional radial flux motors that use silicon steel laminations, axial flux motors face a 3D magnetic circuit that cannot be handled by conventional silicon steel. The current mainstream solution is SMC (soft magnetic composite) – iron powder coated with an insulating layer and then compacted into shape – which can form complex disc-type geometries in one pressing step.

The core typically represents about 10-15% of the total motor cost. Although the share is modest, the process technology for SMC is demanding: the insulating coating on each powder particle must be extremely thin to achieve high density, yet it must not be damaged during high-pressure compaction – requiring long-term process validation. In addition, the raw material for soft magnetic alloy powder costs about twice as much as silicon steel, further increasing the process cost.

3. Encapsulation Material – Smallest Share, Yet a Critical Role

Encapsulation materials make up the smallest portion of the axial flux motor rotor cost.

Encapsulating compounds are mainly used to fill the gaps between the housing and the core, and between the housing and the coil windings, serving functions such as thermal conduction, electrical insulation, fixation, and stress dispersion. Because axial flux motors are flat with limited surface area for heat dissipation, thermal management is a major challenge. Using high-thermal-conductivity potting compounds (e.g., with a thermal conductivity of 2-3 W/m·K) is one important measure to improve cooling.

However, in terms of cost contribution, encapsulation materials are far behind magnets and the core, accounting for only a small fraction of the overall rotor BOM.

4. Summary: Magnets > Core > Encapsulation

Putting it all together, the cost ranking for an axial flux motor rotor is clear:

The magnet grade is the largest cost component in an axial flux motor rotor, accounting for 35-40% of the total motor cost – far exceeding the core and encapsulation. This also explains why the industry views magnets as both the “heart” and the “Achilles’ heel” of axial flux motors: they determine not only the motor’s performance ceiling but also its cost floor.

5. SDM: Flexible Production Line Empowers Volume Delivery

In the industrialisation of axial flux motor rotors, efficient and flexible manufacturing capability is crucial. SDM (Hangzhou Shengshideng Magnetic Materials Co., Ltd.) – a national-level high-tech enterprise focused on magnets and magnetic solutions – has built a distinct advantage in the axial flux motor rotor field.

On the production side, SDM has set up a flexible assembly line in its factory, enabling rapid changeovers between different types of axial flux motor rotor assemblies. This flexible manufacturing capability allows efficient response to customised demands for multi-variety, small-batch production, greatly improving both throughput and delivery agility.

To date, SDM has already achieved volume delivery of multiple axial flux motor rotor models. As axial flux motors rapidly penetrate trillion-yuan markets such as new energy vehicles, humanoid robots, and low-altitude economy, SDM’s flexible line layout and proven mass-delivery track record are building a solid moat for the company in an increasingly competitive landscape.