High Quality Step Lap CRGO Transformer Lamination Core
Sep 28, 2025
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Step Lap CRGO Transformer Lamination Core Product Description
A Step Lap CRGO Transformer Lamination Core is a high-efficiency transformer core constructed from thin sheets of Cold Rolled Grain Oriented (CRGO) steel, which are assembled with a mitred step-lap joint. This innovative design, originally developed by Westinghouse, features overlapping steps that reduce the magnetic air gap, leading to lower core losses, lower noise levels, and faster assembly compared to traditional overlapped or butt joints.
Key Components and Purpose
- CRGO Steel:
This specialized electrical steel has a high magnetic permeability and mechanical strength, allowing for highly efficient magnetic flux paths along the rolling direction.
- Laminations:
The core is built from thin, insulated sheets of CRGO steel. The laminations are coated with an insulating material to prevent eddy currents, which cause energy loss.
- Step-Lap Joint:
Instead of simple overlapping joints, the laminations are arranged in a specific stepped or tiered pattern. This "step" design progresses across the core.
Benefits of the Step-Lap Design
1.Reduced Losses:
The stepped design minimizes the air gaps at the joints, which are areas of high reluctance, leading to reduced magnetic flux leakage and significantly lower core losses.
2.Lower Noise:
By reducing the magnetic stress on the core, the step-lap design also contributes to a lower noise level in the transformer.
3.Faster Assembly:
The specific arrangement of the stepped joints allows for quicker and more efficient assembly of the transformer core.
4.Cost-Effective:
By reducing core losses and improving assembly, the step-lap design helps lower the overall material and manufacturing costs of high-efficiency transformers.
Transformer Iron Core Manufacturing Process
- Material Preparation: CRGO steel is slit into coils and then cut into individual laminations.
- Joint Creation: The laminations are precisely cut with a stepped pattern.
- Stacking: The cut laminations are then stacked, forming the core in a stepped configuration.
- Assembly: The stacked core limbs and yokes are assembled together.
- Annealing: The assembled core undergoes a stress-relief annealing process to improve its magnetic properties and reduce residual stresses from manufacturing.
- Testing: Finally, the core is rigorously tested to ensure it meets performance standards for magnetic properties and core losses.
Electrical Silicon Steel specifications
Exquisite Quality & Fully Assembled Cores
- Maximum Weight of Automated Stacked Core: 60 Tons
- Maximum Weight of Manually Stacked Core: 120 Tons
- Gap Precision at the Joint: Less than 1.0mm
- Window Height Accuracy: ±1mm
- Window Width Accuracy: ±1mm
| Type | Grade | Width | Max Core Loss@P1.7T/50Hz | Lamination Factor(%) | Min Induction@B800 |
| Common Type | 23Q110 | 35-1200mm | 1.10w/kg | 97.2 | 1.82T |
| 23Q120 | 1.20w/kg | 97.2 | 1.82T | ||
| 27Q120 | 1.20w/kg | 97.5 | 1.82T | ||
| 30G120 | 1.20w/kg | 98 | 1.82T | ||
| High Induction Type |
B20P085 | 35-1200mm | 0.85w/kg | 97 | 1.86T |
| B23P085 | 0.85w/kg | 97.2 | 1.88T | ||
| B23P090 | 0.90w/kg | 97.2 | 1.88T | ||
| B23P095 | 0.95w/kg | 97.2 | 1.88T | ||
| B23P100 | 1.00w/kg | 97.2 | 1.88T | ||
| B27P095 | 0.95w/kg | 97.5 | 1.89T | ||
| 27QG100 | 1.00w/kg | 97.5 | 1.89T | ||
| B30P120 | 1.20w/kg | 98 | 1.89T | ||
| Domain Refined High Induction Type(Laser) |
B20R070 | 35-1200mm | 0.70w/kg | 97 | 1.86T |
| B23R085 | 0.85w/kg | 97.2 | 1.88T | ||
| B27RK085 | 0.85w/kg | 97.5 | 1.89T |
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Manufacturing Process
1. Raw Material Sourcing
2. Slitting
3. Punching
4. Laminating
5. Core Forming
6. testing
GNEE EC
Founded in 2008 and located in Anyang in China, Gnee Electric is a high-tech enterprise specializing in researching and manufacturing iron core products.
The company currently occupies over 20,000 square meters and employs more than 200 people, including over 80 professionals. After more than 18 years of development, we have built our own magnetic material production base and independently develope, produce, and sell various kinds of iron cores. The common types include silicon steel cores, motor cores, transformer cores, toroidal iron cores, special-shaped cores, custom cores, and others. Our cores are widely applied in different sectors including transformers, motors, mutual inductors, voltage stabilizers, welding machines, magnetic amplifiers, and instrumentation, providing diverse core solutions to global customers.
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Why Choose GNEE EC?
GNEE EC was founded in 2008, which is a National High-tech Enterprise & Famous Brand Enterprise in China, developing into a professional manufacturer and supplier of high-quality iron cores.
18+
Over 18 years of success in the iron core industry;
National High-tech Enterprise & Famous Brand Enterprises in China;
200+
Over 200 employees;
The R&D team has more than 80 experienced engineers and the production team has more than 100 skilled staffs;
35+
Annual turnover up to 35 million dollor per year;
Owns many sets of highly automatic winding, annealing, and assembling machines;
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Over 1000 customers in domestic and overseas markets;
core Products are exported to more than 70 countries in the world;
Gnee Iron Core Factory Overview
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Edison Zhang
CEO
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Industries Served
Automobile Industry
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Transformer Applications
Our Mission
Strive To Create world-class Iron core brand
With 18 Years of industry experience, we focus on the research, development, and manufacturing of high-quality iron cores for electricity, industrial control, new energy, and automotive markets