Lamination thickness has a direct impact on how transformers, motors, and other magnetic components perform. It affects core loss, efficiency, manufacturability, and ultimately cost. In practice, choosing the right electrical steel thickness is usually a balancing act between performance targets and production constraints rather than simply picking the thinnest material available.

The sections below cover common thickness ranges, their impact on core loss, and some of the manufacturing trade-offs involved.

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Why Thickness Matters

Thinner laminations help reduce eddy current loss in high-frequency applications like EV traction motors, though they also increase material and processing cost.
Most manufacturers now specify electrical steel directly in mm or mils because gauge systems can vary across standards.
Manufacturing also matters. Very thin laminations are harder to stamp cleanly and tend to increase tooling wear.
Operating frequency is usually the main factor behind thickness selection.

What is Electrical Steel Thickness?

Electrical steel thickness refers to the thickness of an individual lamination sheet used in a magnetic core. These thin sheets, commonly called laminations, are stacked together to form the magnetic core.

This measurement is usually expressed in millimeters (mm) or in mils, which are thousandths of an inch (1 mil = 0.001"). Older gauge-based naming systems still appear occasionally, although most manufacturers now specify thickness directly in mm or mils. Because of this, most engineers rely on direct thickness measurements rather than gauge numbers.

A quick comparison chart of the common values is here:

Metric: 0.23 mm, 0.27 mm, 0.35 mm, 0.50 mm
Imperial (mils): 0.009 in (9 mil), 0.011 in (11 mil), 0.014 in (14 mil), 0.020 in (20 mil)

Common Thicknesses and Grades

Choosing the right electrical steel thickness is substantiated by the type of material and final use. The main two types are Grain-Oriented (GO) and Non-Oriented (NO) steel.

GOES is mainly used in transformer cores, where directional magnetic performance matters. GOES standard thicknesses given in the technical data sheets for grain-oriented electrical steel generally vary from 0.18 mm to 0.35 mm.

Non-oriented grades are commonly used in motors and generators because magnetic flux changes direction continuously during operation. The choice of lamination thickness, gauge for NO steel is a long one, matching many different kinds of uses.

Material grades often include thickness in their name. For example, a grade like M235-35A tells us two things: it has a maximum core loss of 2.35 W/kg (at 1.5T, 50Hz) and a thickness of 0.35 mm. This system directly links performance to the material's physical size.

Material Type	Common Thickness (mm)	Common Thickness (inches/mils)	Typical Application Area
Grain-Oriented (GO)	0.18, 0.23, 0.27, 0.30, 0.35	0.007" (7-mil), 0.009" (9-mil), 0.011" (11-mil), 0.012" (12-mil), 0.014" (14-mil)	Power & Distribution Transformers
Non-Oriented (NO)	0.35, 0.50, 0.65	0.014" (14-mil), 0.020" (20-mil), 0.026" (26-mil)	Motors, Generators, Ballasts
Thin Gauge / High-Frequency	≤ 0.20	≤ 0.008" (≤ 8-mil)	High-speed motors, EV traction motors, High-frequency inductors

The Link Between Thickness and Core Loss

In electrical steel, thickness is never just a size specification. Change the gauge a little, and the core loss result can move with it.

A thicker sheet may be easier to process, and sometimes the purchase price looks better too. But inside the core, thickness gives eddy currents more room to circulate. Those currents do not add output; they mostly show up as heat. Once that heat starts affecting temperature rise or efficiency, the saving at the material stage may not look so simple.

This is why engineers pay close attention to tested core loss, not just the grade name. Two coils can sit under the same grade, but if the thickness or loss value is different, they may behave differently in a transformer, motor, or reactor. In designs with tighter temperature margins or higher frequency, it can become the point that decides whether the material is suitable.

HWHG’s core-loss-based pricing follows this same logic. We do not treat electrical steel as one broad grade category. We look at the verified loss value and price the material according to the performance it can actually deliver.

For customers, the price difference is easier to understand this way. Lower core loss means more room to control heat and meet efficiency targets. A higher-loss material can still be the right choice for a less demanding application, but it should not be priced as if it offers the same performance.

When thickness changes the loss result, the value of the material changes with it. That is the idea behind HWHG’s pricing model.

Process Impact on Steel Performance

If the manufacturing and processing are not carried out correctly, it is possible to lose the benefits associated with the ultra-thin electrical steel thickness. From a practical standpoint, thickness poses a number of challenges.

Stamping and Punching

Very thin laminations are harder to stamp consistently and usually require tighter die control and more frequent tooling maintenance.

Burr formation is a major concern with thin laminations because damaged coatings can create electrical bridging between layers.

Cutting Methods

Although the laser or waterjet cutting is preferable for initial prototypes, these processes may have adverse effects on the material. Laser cutting can create a heat-affected zone (HAZ) near the cut edge, which may locally degrade magnetic performance. This phenomenon is more distinct in very thin electrical steel thickness, as the damaged zone constitutes a greater part of the lamination's cross-section.

Core Stacking

Core design typically aims to maximize the amount of active steel within a limited volume. This directly affects stacking factor. With thinner laminations, more layers are needed to construct a core of a specific height. Because thinner cores require more laminations, the additional coating layers can slightly reduce usable steel volume.

Electrical steel produced by HWHG

Selecting the Right Lamination Thickness

In practice, thickness selection is usually driven by operating frequency, efficiency targets, manufacturability, and overall production cost.

Manufacturers offer a wide range of grades for different frequency and efficiency requirements.

Application	Typical Frequency	Recommended Thickness	Key Rationale
Large Power Transformers	50/60 Hz	0.23mm - 0.30mm (GO)	Lifetime efficiency is the top priority. Thinner GO steel cuts core loss at standard grid frequencies.
Standard Industrial Motors	50/60 Hz	0.50mm - 0.65mm (NO)	A balance of cost and performance. Core losses matter, but material and processing costs are major factors.
High-Efficiency / VFD-Driven Motors	50 - 400 Hz	0.35mm (NO)	VFD-driven motors also see additional high-frequency losses that standard laminations don't handle particularly well.
EV Traction Motors / Aerospace	400 Hz - >1 kHz	0.10mm - 0.27mm (NO)	Very high speeds and frequencies make eddy currents the biggest source of loss. Cutting loss is critical for range, power, and heat management.

Lamination thickness affects not only efficiency, but also tooling strategy, thermal behavior, and manufacturing cost, so it is usually evaluated together with operating frequency and production constraints.

For high-speed motors, thinner laminations are often worth the extra cost. For standard industrial equipment, not always.

Most Asked Questions (FAQ) about Electrical Steel Thickness

Q1. How does electrical steel gauge differ from thickness in mm/inches?

A: For engineering work, direct thickness measurements in mm or mils are generally more reliable than gauge numbers.

Q2. Why not use the thinnest electrical steel for every application?

A: Ultra-thin laminations reduce core loss, but they also increase stamping difficulty, tooling wear, and manufacturing cost.

Q3. Does the insulation coating affect the effective thickness of a core?

A: Yes. Even though the coating is thin, it still affects the stacking factor once hundreds of laminations are involved. Laminations that are thinner bring about more layers of coating in a core. If not handled in the right way, this can lead to a lower stacking factor.

Q4. Would thicker electrical steel (e.g., 0.65mm) be more advantageous for low-frequency applications?

A: It wouldn't be "better," but it would certainly be more "cost-effective" most of the time. At very low frequencies like 50/60 Hz, eddy current losses from a 0.50mm or 0.65mm lamination are often acceptable. The savings in both material and processing costs are substantial in these cases, thereby making the thicker gauges the first choice for standard motors and ballasts, where peak efficiency is not the only target.

Q5. What is the process involved in measuring and controlling lamination thickness during manufacturing?

A: During the rolling process, it is controlled through high-precision non-contact methods. Technologies such as X-ray or laser gauging systems monitor the thickness of the steel strip in real-time. They send feedback to the rolling mill controls, thereby ensuring the entire coil runs with tight tolerances.

Electrical Steel Lamination Thickness: Performance, Core Loss, and Manufacturing Trade-Offs

Non-Oriented Electrical Steel for Motor Cores: A Thorough Guide

CRGO vs. Hi-B CRGO Coil: Which Grade Is Better for Transformer Core Production?

What Is Grain-Oriented Electrical Steel? GOES, CRGO, Core Loss, and Transformer Applications Explained

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