Why lamination thickness matters in electrical equipment
For a transformer or motor manufacturer, Siliziumstahl-Laminierungsdicke is not simply a purchasing specification. It influences magnetic losses, the number of sheets in a core stack, processing cost and assembly. Selecting the thinnest material available is not automatically the most economical choice. The right option depends on operating frequency, magnetic flux density, material grade, winding design and the required efficiency level.
Electrical steel is manufactured as thin sheets or strip with insulation between adjacent laminations. Compared with a solid metal core, this construction limits circulating eddy currents. Within the simplified classical eddy-current model, loss is proportional to the square of sheet thickness when other material and operating variables are held constant. Real assembled-core losses are more complex because they also depend on hysteresis, stress, joints, flux waveform and processing damage.
Comparing common lamination thicknesses
| Nominal thickness | Typical consideration | Important qualification |
| 0.23 mm | Thin grain-oriented material for demanding power-frequency core designs | Material grade and supplier availability must be checked |
| 0.27 mm | Grain-oriented option where lower material loss is a priority | Compare certified loss data at the required flux density |
| 0.35 mm | Widely used dimension for electrical steels and many lamination designs | Available properties differ across oriented and non-oriented grades |
| 0.50 mm | Common non-oriented sheet option for selected motor and general-purpose core designs | Does not imply suitability for every transformer or frequency |
This table is a decision aid, not a claim that every thickness is available in every steel grade. For example, IEC 60404-8-7 addresses grain-oriented electrical steel at 0.20, 0.23, 0.27, 0.30 and 0.35 mm, while IEC 60404-8-4 covers different nominal thicknesses for fully processed non-oriented steel.
How thickness affects core loss and manufacturing cost
Eddy-current loss. Thinner, adequately insulated sheets tend to reduce the classical eddy-current contribution at a fixed frequency and peak flux density. However, total core loss must be validated using data for the actual grade and final assembly.
Material and tooling cost. A thinner sheet generally means more pieces for the same gross stack height. Handling, stamping conditions, tooling wear and assembly time can change. Material price per kilogram may also vary by grade and sourcing volume.
Stack dimensions. If a design needs a specified effective magnetic cross-section, the thickness and insulation coating influence the number of laminations and finished stack height. The drawing should state whether the critical dimension is a physical stack height or a net magnetic area.
Processing quality. Burrs, residual stress, coating damage and inconsistent stacking may offset some of the potential benefit from a thinner sheet. Good material data is only one part of good core performance.
Is 0.35 mm or 0.50 mm better for a 50/60 Hz transformer?
There is no universal answer. A lower-loss design may use a thinner, suitable grade, but the steel’s specific loss, magnetization characteristics and cost must be compared under the same test conditions. Transformer geometry, flux density and assembly method can matter as much as thickness.
A useful engineering comparison requests the specific total loss in W/kg at the relevant frequency and polarization/flux-density condition, together with grade identification and test method. For magnetic-property evaluation, IEC 60404-3 describes measurement using a single sheet tester at power frequencies.
For EI-style designs, Tianxiang’s EI-Laminierung product range includes standard sizes and customized dimensions. The appropriate sheet thickness should be confirmed against the exact material and project requirements rather than inferred from the size designation alone.
What to include in a lamination thickness RFQ
For a practical quotation, share the application and operating frequency; steel grade or target magnetic loss; nominal thickness and allowable variation; lamination drawing; winding window and mounting features; projected stack height; insulation requirement; annual quantity; and whether the laminations need annealing or other processing.
An OEM that has not finalized the grade can provide its core-loss or temperature-rise target and request a material comparison. If the part is not a standard EI geometry, review Tianxiang’s custom-made laminations and send a drawing for a feasibility discussion.
Frequently asked questions
Does thinner silicon steel always improve transformer efficiency?
Not always. Thinner sheets can lower eddy-current losses, but the complete efficiency result depends on steel grade, magnetization, joints, stacking and the rest of the transformer design.
Is 0.35 mm electrical steel always grain-oriented?
No. A thickness is not a material grade. Grain-oriented and non-oriented products can have overlapping nominal thicknesses but different magnetic properties.
Can the same EI lamination size use different steel thicknesses?
Potentially, yes, subject to tooling, material availability and the specified assembled stack. Confirm the combination with the manufacturer before ordering.
Which documents should I request from a supplier?
Ask for grade identification, relevant material certificates, dimensions and tolerances, agreed inspection criteria and any required magnetic test data.
Discuss your EI lamination requirements with Tianxiang
Tianxiang manufactures EI-Laminierungen, UI-Laminierungen Und custom silicon steel components for electrical equipment manufacturers. Contact our team with your drawing, target thickness, application and quantity to review the next step.
Technical references: IEC 60404-8-7; IEC 60404-8-4; IEC 60404-3.
