Quick Answer

Non-oriented electrical steel, or NGOES, is the preferred core material for motors and other rotating electrical machines because its magnetic properties are relatively balanced in different directions.

When choosing NGOES, the key is not to pick the lowest-loss grade on the datasheet. The grade must match the motor’s speed, frequency, lamination thickness, stamping process, coating requirement, and cost target.

Lower core loss helps reduce heat and improve efficiency, especially in high-speed and EV motors. But if the material is too difficult to stamp, stack, or control in mass production, the total cost may increase. The right grade is the one that balances magnetic performance with manufacturability.

Why Motor Cores Need Specialized Magnetic Materials

Motor cores operate under changing magnetic fields, so the material must carry magnetic flux with as little energy loss as possible.

Conventional structural steel is not designed for this job. It produces more core loss and heat, especially at higher electrical frequencies.

Most motor cores are therefore made from thin, insulated electrical steel laminations. The thin sheets reduce eddy-current loss, while the steel’s magnetic properties affect efficiency and heat generation.

What Is Non-Oriented Electrical Steel?

Non-oriented electrical steel is used to make laminated stator and rotor cores in motors and other rotating electrical machines. It usually contains silicon, which increases electrical resistivity and helps reduce eddy-current loss.

“Non-oriented” does not mean the steel has identical magnetic properties in every direction. It means its magnetic properties are more balanced across directions than grain-oriented electrical steel.

This matters because magnetic flux in a motor does not follow one fixed direction. It rotates through the stator and rotor during operation. A steel designed to perform best in only one direction would lose much of its advantage in this working condition.

That is why NGOES is used in motor cores, while grain-oriented electrical steel is mainly used in transformer cores.

Why Motors Need NGOES Instead of GOES

GOES and NGOES are designed for different magnetic conditions. The choice is not only about comparing loss values; it also depends on how the magnetic flux moves inside the machine.

GOES performs best when magnetic flux mainly follows one direction. In transformer cores, this works well because the flux path is relatively fixed. Along the rolling direction, GOES can provide low core loss and high permeability.

Motor cores work differently. During operation, the magnetic field moves around the stator and rotor instead of staying aligned with one direction. Because of this, GOES cannot maintain its best magnetic performance throughout the motor core.

NGOES is more suitable for this condition because its magnetic properties are more balanced across directions. That is why it is commonly used in motors, generators, alternators, and compressors, where the magnetic field rotates or changes direction.

How NGOES Is Made

Production Process of Non-Oriented Electrical Steel

The performance of NGOES depends heavily on processing quality. Small differences in rolling, annealing, thickness control, and coating can affect core loss, permeability, and manufacturability.

A typical production route includes:

Melting and alloying
Iron is melted, and elements such as silicon and aluminum are added in controlled amounts.
Hot rolling
The slab is rolled at high temperature to reduce thickness and prepare the material for further processing.
Cold rolling
The steel is reduced to its final or near-final thickness at room temperature.
Annealing
Heat treatment relieves rolling stress and helps develop the required magnetic properties.
Insulation coating
A thin insulating layer is applied to the surface so each lamination can be electrically separated in the motor core.

For motor manufacturers, consistency matters as much as the basic grade. If coating thickness, flatness, or magnetic loss varies too much between coils, it can affect production stability and final motor performance.

Why Insulating Coatings Matter

The coating on NGOES is thin, but it has a direct effect on how the finished motor core performs. Each lamination needs to be insulated from the next one so current does not flow freely between sheets.

If the insulation is weak or uneven, interlaminar current can increase. The result is higher eddy-current loss, more heat, lower efficiency, and less stable motor performance under load.

The difficult part is not only applying a coating. It is applying it evenly across a full steel coil. In coil production, continuous coating lines help control coating thickness, curing temperature, surface uniformity, and coil-to-coil consistency. This is especially important when the material will be stamped at high speed or used in large-volume motor production.

The coating also has to survive the next steps. Stamping, stacking, handling, welding, bonding, or heat exposure can all damage a weak coating. If the coating scratches, flakes, burns off, or loses insulation resistance, the steel grade may still be correct, but the finished core may not meet the expected performance.

Strip Annealing and Coating Line (SACL) in HWHG Factory

Key Performance Numbers Engineers Look At

After coating, engineers usually look at the steel’s magnetic data and processing behavior together. The coating helps control current between laminations, while the steel itself has to limit heat, carry flux, and pass through stamping without excessive burrs or tool wear.

Core Loss

Core loss is the power lost as heat when the steel is repeatedly magnetized. It is usually given in W/kg under set test conditions, such as frequency and flux density.

Lower core loss helps the motor run cooler and more efficiently. It becomes more important when the motor runs at higher speed or higher frequency.

Magnetic Permeability

Magnetic permeability shows how easily the steel can be magnetized.

Higher permeability can help the core reach the required flux level with less magnetizing current. This can support efficiency or compact motor design, depending on the application.

Magnetic Saturation

Magnetic saturation happens when the steel is already carrying a high level of magnetic flux and cannot increase much further.

A higher saturation level helps the core handle stronger magnetic fields before performance starts to drop. This is useful in motors that need higher torque or power density.

Main Applications of NGOES

NGOES is used in many products with rotating or changing magnetic fields. The grade is usually selected by motor speed, efficiency target, lamination thickness, coating requirement, and production cost.

Application	Selection Focus
Standard motors	Balanced core loss, good stamping quality, stable cost
Pump and fan motors	Efficiency, heat control, reliable long-hour operation
Servo and industrial motors	Magnetic consistency, low burr, stable batch quality
High-speed motors	Lower core loss, thinner laminations, better heat control
EV traction motors	Premium low-loss grades, thin gauge, high-frequency performance
Generators and alternators	Loss control, magnetic stability, coating reliability
Compressors	Long-hour efficiency, heat reduction, production stability
Small electromagnetic parts	Frequency, part size, stamping method, cost

Standard motors usually use balanced grades. High-speed and EV motors need lower-loss, thinner-gauge materials, while smaller electromagnetic parts are often selected by size, stamping method, and cost.

Why High-Speed Motors Often Require Lower-Loss NGOES

High-speed motors often operate at higher electrical frequencies, which increases core loss and heat in the stator. The effect also depends on pole count, flux density, and inverter harmonics, not speed alone.

These motors often use thinner NGOES with lower loss at the relevant operating frequency. Thinner laminations help limit eddy-current loss, which is especially important in EV traction motors, servo motors, compressors, and other compact motors with tight thermal limits.

NGOES vs. GOES: Main Differences

Feature	NGOES	GOES
Full name	Non-oriented electrical steel	Grain-oriented electrical steel
Grain structure	Relatively random grain structure	Grains mainly aligned in one direction
Magnetic behavior	More balanced across directions	Best along the rolling direction
Suitable flux condition	Rotating or changing magnetic fields	Mostly fixed magnetic flux path
Common applications	Motors, generators, alternators, compressors	Power and distribution transformers
Core loss behavior	More consistent across different directions	Very low along the rolling direction
Off-axis performance	Better suited to changing flux direction	Drops when flux moves away from the preferred direction
Cost note	Often practical for motor-core production	Varies by grade, thickness, and supply

A simple way to read the table: NGOES is selected for rotating machines, while GOES is selected for transformer cores with a mostly fixed flux path.

How to Choose the Right NGOES Grade

The right NGOES grade depends on motor speed, efficiency target, stamping process, coating requirement, and cost.

For efficiency or heat control, check core loss and lamination thickness. For high-speed motors, thinner gauge and higher-frequency loss data matter more. For mass production, stamping quality, burr control, coating adhesion, and coil consistency should be checked together.

The best grade is not always the highest-performance grade. It is the one that meets the motor design target without adding unnecessary production difficulty.

HWHG supplies NGOES steel coils for motor-core production, with options for different thicknesses, coating requirements, and application needs. If you are comparing grades for standard motors, high-speed motors, compressors, or EV-related applications, HWHG can help match the coil specification to your target loss level, stamping process, and production volume.

Practical NGOES Selection Checklist

Check	What to confirm
Operating frequency	Core loss data at the motor’s actual frequency range
Coil thickness	Whether the gauge is suitable for the expected eddy-current loss
Stamping	Burr height, tool wear, hardness, and part accuracy
Coating	Insulation resistance, adhesion, and compatibility with welding or annealing
Coil quality	Flatness, thickness tolerance, surface condition, and coil-to-coil variation
Supply	Available grades, coil dimensions, lead time, and minimum order quantity

Do not approve a grade from the datasheet alone. Test the sample coil under the planned stamping and stacking process, especially when burr limits or coating conditions are critical.

Common Questions

1. Is non-oriented electrical steel magnetic?

Yes. NGOES is a soft magnetic material. It can be magnetized and demagnetized easily, which makes it suitable for motors, generators, and other electromagnetic devices.

2. Why is silicon added to electrical steel?

Silicon is added mainly to increase electrical resistivity. Higher resistivity helps reduce eddy-current loss, which can lower heat generation and improve motor efficiency.

3. What are the standard grades of NGOES?

NGOES grades are usually defined by standards such as ASTM, IEC, EN, or JIS. Grade names often relate to thickness, maximum core loss, or magnetic performance under specified test conditions.

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