As EV traction motors move toward higher rotational speeds and greater power density, motor-core material selection becomes more demanding.

Non-grain-oriented electrical steel (NGOES) remains the established material for rotating electrical machines, while amorphous metal is attracting attention because of its low magnetic loss, particularly at higher frequencies.

Lower core loss alone, however, does not determine the better motor-core material. Saturation flux density, motor geometry, manufacturability, and production cost also need to be considered.

Key Points

Amorphous metal can offer lower high-frequency core loss than conventional NGOES.
NGOES generally provides higher saturation flux density and more mature motor-core manufacturing.
The thin, brittle form of amorphous ribbon makes motor-core production more difficult.
Replacing NGOES with amorphous metal usually requires design and manufacturing changes rather than a direct material substitution.
Material selection depends on operating frequency, magnetic loading, motor geometry, and production requirements.

Why High-Speed EV Motors Change the Material Question

As motor speed increases, the electrical frequency seen by the stator core can also increase.

At higher frequencies, magnetic losses become more important because the core is magnetized and demagnetized more frequently. This places greater emphasis on material thickness, electrical resistivity, and core-loss performance.

This is one reason thinner NGOES grades are increasingly considered for high-speed traction motors.

Amorphous metal takes this concept further. It is produced as an extremely thin ribbon and has relatively high electrical resistivity, characteristics that can help reduce eddy-current loss at elevated frequencies.

Amorphous Metal vs NGOES: What Changes at Higher Frequency?

The main attraction of amorphous metal in high-speed motor applications is its high-frequency loss performance

Its non-crystalline atomic structure can support relatively low hysteresis loss, while its very small ribbon thickness helps limit eddy-current formation

NGOES is considerably thicker than typical amorphous ribbons, although thin-gauge NGOES has been developed for applications where high-frequency loss is important.

High-frequency performance comparison of amorphous metal and NGOES core loss versus frequency

As frequency rises, this thickness difference can become more relevant.

Core-loss values should still be compared under equivalent test conditions, including:

frequency
flux density
material thickness
test method
specimen condition

A lower published loss value alone does not determine finished traction-motor performance.

Core Loss Is Only One Part of Motor Performance

High-frequency core loss is important, but motor-core material selection cannot be based on loss alone.
One important difference between amorphous metal and NGOES is saturation flux density.
High-grade NGOES generally supports higher magnetic flux density than typical iron-based amorphous materials. This matters when high magnetic loading is required within a limited motor volume.
A lower saturation level can require changes to:

stator tooth dimensions

yoke dimensions

magnetic loading

motor geometry

Amorphous materials are more attractive in designs where high-frequency magnetic loss in EV motors is a major efficiency concern.

Why Amorphous Metal Cannot Simply Replace NGOES

An amorphous motor core is not simply an NGOES core made from a different material.
The two materials differ in thickness, mechanical behavior, and processing requirements.
A motor originally designed around NGOES may therefore require changes in:

magnetic circuit dimensions
ribbon handling
core support
stacking or bonding methods
manufacturing equipment

Moving from NGOES to amorphous material is therefore better treated as a motor-core redesign decision rather than a direct material substitution.

Manufacturing Challenges in Amorphous Motor Cores

Manufacturing is one of the main differences between amorphous metal and NGOES.

Conventional NGOES motor laminations already use established cutting, stamping, stacking, and joining processes.

Amorphous ribbon is much thinner and more brittle, which can make conventional lamination processing more difficult and may require different cutting, handling, stacking, or bonding methods.

Stacking factor also needs attention. Because a very thin ribbon requires more individual layers and includes insulation or interlayer interfaces, the amount of active magnetic material within a given core volume may differ from that of conventional NGOES laminations.

These factors can affect:

production speed
material utilization
dimensional control
equipment requirements
finished-core cost

From the material-supply side, consistency becomes especially important as ribbon thickness decreases. HWHG produces both non-grain-oriented electrical steel and iron-based amorphous ribbon, with established controls for dimensional and magnetic-property consistency.

HWHG iron-based amorphous ribbon coils for motor core material applications

Its amorphous ribbon is already in mass production and has been supplied for new-energy vehicle applications. Specific customer information remains confidential. Buyers and engineers evaluating either material can contact HWHG for relevant specifications and test data.

Where NGOES Still Has the Advantage

NGOES retains practical advantages in high-volume traction-motor production.

Its main practical advantages include:

higher saturation flux density
established stamping and lamination processes
compatibility with high-volume motor-core production
relatively robust mechanical handling

Thin-gauge NGOES can also reduce high-frequency loss while retaining many of these manufacturing advantages.

Where Amorphous Materials May Make More Sense

Amorphous materials are more attractive in designs where high-frequency magnetic loss is a major efficiency concern.

Potentially suitable applications include motors where:

electrical frequency is high
core loss has a significant effect on efficiency
thermal management is demanding
the motor architecture can accommodate different core-manufacturing methods
efficiency gains justify additional manufacturing complexity

What Motor Designers Should Compare Before Changing Core Material

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Key factors motor designers should compare when choosing amorphous metal or NGOES for EV motors

Amorphous metal and NGOES should be compared under the intended operating and manufacturing conditions.

Key factors include:

Factor	Why It Matters
Core loss at operating frequency	Determines how the material behaves beyond standard low-frequency test conditions
Flux density	Core-loss comparisons should use equivalent magnetic loading
Saturation flux density	Influences magnetic loading and core geometry
Material thickness	Affects eddy-current loss and core construction
Stacking factor	Influences the amount of active magnetic material in the core
Mechanical properties	Affect cutting, handling, assembly, and durability
Core manufacturing method	Determines whether existing lamination processes can be used
Production scale	Affects manufacturing feasibility and cost
Finished-core performance	Material-level data does not capture all effects introduced during core production

The relevant comparison is at the motor-system level, not only at the material datasheet level.

Conclusion

Amorphous metal and NGOES address different priorities in high-speed EV motors.

Amorphous materials can reduce high-frequency magnetic loss, while NGOES retains advantages in saturation capability and established high-volume manufacturing.

The better fit depends on the motor design, not just the material datasheet.

HWHG supplies both NGOES and iron-based amorphous ribbons. Buyers evaluating the two material routes can contact us for relevant specifications and test data.

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