Non-oriented electrical steel (often abbreviated NOES) is a cold-rolled, silicon-alloyed electrical steel engineered to have nearly the same magnetic properties in every in-plane direction. That isotropy makes it the material of choice for rotating machines — motors, generators, and many types of actuators — where the magnetic flux changes direction continuously.
Como principal proveedor y transformador de acero, Weijunli Steel will explain composition, manufacturing, magnetic performance, standards, typical applications, and practical procurement guidance for engineers and buyers.
Basic Chemistry and Product Forms
At its core, non-oriented electrical steel is a low-carbon steel alloy with added silicon (typically about 1.0–3.5% Si) and tightly controlled impurities (very low C, S, and P). Silicon increases electrical resistivity and reduces eddy-current losses at AC frequencies, while low carbon minimizes magnetic aging and hysteresis loss.
Common product forms include:
- Coils: This is the main form of procurement for bulk manufacturers and large stamping plants. It allows customers to flexibly punch stator and rotor cores according to their own designs, which is the foundation for achieving large-scale production and cost control.
- Cut laminations y stacked cores: suitable for prototype development, small-batch production, or manufacturers lacking stamping capabilities. Directly providing assembled finished products significantly shortens the research and development cycle and reduces production complexity.
Typical thicknesses: 0.35 mm, 0.50 mm, 0.65 mm (thinner gauges used for lower loss at higher frequencies)
NOES is manufactured and sold to meet magnetic loss, permeability, and punchability criteria required by motor designers.
How it’s Made — Key Manufacturing Steps
The production route for non-oriented electrical steel combines thermo-mechanical processing and annealing steps to produce a clean, low-loss, isotropic material:
- Steelmaking & casting: Melt chemistry is tightly controlled to minimize impurities and set Si content. Continuous casting produces slabs with low inclusion levels.
- Hot rolling & pickling: Slabs are hot-rolled, pickled to remove scale, and prepared for cold rolling.
- Cold rolling: Multi-pass cold rolling reduces thickness to the target gauge and introduces deformation that will be removed in annealing.
- Intermediate anneal(s): Controlled anneals partially recrystallize the structure, improving formability and preparing the microstructure for final annealing.
- Final anneal (decarburization): A decarburizing anneal in a controlled atmosphere reduces residual carbon and sets the magnetic texture required for low loss.
- Insulating coating: A thin insulating varnish or inorganic coating (typically 1–3 µm) is applied to increase inter-laminar resistance and reduce eddy currents in assembled cores.
- Slitting & packing: Coils are slit to the required widths and packed with protective interleaves for shipment.
Quality control at each step (chemical analysis, thickness control, and magnetic testing) is essential to guarantee consistent magnetic performance
Magnetic and Physical Properties
The defining attributes of non-oriented electrical steel are its low core loss and reasonably high permeability in all in-plane directions:
- Core loss (W/kg): Measured at specified flux density and frequency (e.g., 1.5 T @ 50 Hz). Buyers should request loss data at the operating point relevant to their machine.
- Permeability: High initial and maximum permeability reduces magnetizing current and improves efficiency.
- Isotropy: Magnetic properties vary little with direction, so NOES suits rotating flux paths.
- Punchability and formability: Coating and thickness selection balance stamping ease against loss performance. Thinner grades reduce eddy losses at higher frequencies but may be harder to stamp.
Designers select the grade that provides the best balance between electrical loss, manufacturability, and cost.
Grades, Standards, and Specification Points
Specify non-oriented electrical steel using internationally recognized metrics rather than only trade names. Key references include IEC/EN (IEC 60404 series), JIS, GB/T, and supplier data sheets. When ordering, include:
- Magnetic loss at a specified flux and frequency (e.g., W/kg @ 1.5 T, 50 Hz).
- Espesor (mm) and acceptable tolerance.
- Coating type (e.g., C5, C3) and coating thickness.
- Punching rating or stamping suitability for the expected die geometry.
Common commercial designations may use loss numbers (e.g., 50W, 35W) or series codes (M-series). Always request the actual tested loss curves for final selection.
Typical Applications
Non-oriented electrical steel is optimized for devices where magnetic flux is multidirectional or rotating:
- AC induction motors and synchronous motors (industrial, HVAC, pumps, blowers).
- Traction and traction-assist motors (electric vehicles and hybrid vehicles) when specific NOES grades are employed.
- Small generators and alternators where isotropic flux is present.
- Chokes, reactors, and some types of transformers with multi-directional flux paths (though grain-oriented steel remains the choice for power transformers with unidirectional flux).
For high-frequency or very high-efficiency designs, thinner NOES grades or specialized low-loss alloys may be selected.
NOES vs. GOES — When to Use Each
- Non-oriented electrical steel (NOES): Isotropic magnetic properties—used in rotating machines and with multi-directional flux.
- Grain-oriented electrical steel (GOES): Has a very high level of anisotropy, which is associated with very low losses with respect to the rolling direction—used for transformer cores that are generally fluxed along the direction of rolling.
As a practical rule: use non-oriented electrical steel for motors and generators; use GOES for power transformer cores.
Testing, Quality Control & Procurement Checklist
Essential tests and documents to request:
- Core loss curves and permeability data at relevant flux/frequency.
- Chemical analysis and Mill Test Certificate (MTC).
- Coating specification (type and thickness) and adhesion tests.
- Mechanical tests (tensile, elongation) are required if mechanical forming is critical.
- Sample laminations for die trials to validate burr, edge quality, and stacking.
Procure a small trial coil or sample laminations before full production orders to ensure stamping and electromagnetic performance meet expectations.
Storage, Handling & Stamping Recommendations
Coils should be stored in dry areas and indoors. Insulating coatings can be flimsy and damaged with handling, so take care with the coils to not nick them or contaminate them. If stamping, ensure to optimize die clearance, selected lubrication, and selected NOES grade satisfies burr and edge conditions for production of high volumes.
Conclusión
Non-oriented electrical steel is the fundamental, cost-effective magnetic material for rotating electrical machines, thanks to its isotropic magnetic behavior and low loss when properly specified. For motor designers and procurement teams, the right NOES grade choice — based on loss data at operating points, thickness, coating, and stampability — directly influences efficiency, manufacturability, and total lifecycle cost.
About Weijunli Steel
Como principal proveedor y transformador de acero, Weijunli Steel is offering wholesale non-oriented steel supply and other common wholesale steel supply. Backed by our highly productive factory, Weijunli Steel is capable of providing tailored custom steel solutions that are based on your specific needs. For years, our factory has maintained stable quality, flexible specs, and competitive delivery times for clients worldwide.
