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Buyer's guide

Silicon Steel & Copper Foil for Transformers from China — A Specialist Materials Buyer's Guide

Sourcing guide for CRGO grain-oriented silicon steel, CRNGO non-grain-oriented steel, copper foil and strip, aluminum strip, and amorphous metal cores from China. Real product images from TransformerStrip. Grade selection, magnetic property verification, MOQ economics.

Information notice: the details below were compiled from published supplier material and buyer correspondence. Specifications, MOQ, lead times and pricing change — confirm every figure with the supplier before you order.

Product range — actual catalogue images

The product images below are hosted on the manufacturer's official website (transformerstrip.com) and link directly to the manufacturer's catalogue. Click any image to view the full specification page in a new tab.

Cold-rolled grain-oriented (CRGO) silicon steel coil — premium electrical steel for transformer cores.

Silicon steel sheet bundle — slit and stacked for direct supply to transformer manufacturers.

High-purity copper foil roll — for transformer winding, busbars, and electrical applications.

Electrical steel grades and applications

Grade familyTypical specificationsMagnetic loss (W/kg at 1.7T)Best applicationsFOB China typical price (per ton)
CRGO Premium (HiB / domain-refined)0.23-0.27mm; B800 ≥ 1.92T0.85-0.95Premium power transformers, energy-efficient distributionUSD 2,800-3,800
CRGO High-grade0.27-0.30mm; B800 ≥ 1.88T0.95-1.10Standard distribution transformers, premium-tier OEMsUSD 2,400-3,200
CRGO Standard0.30-0.35mm; B800 ≥ 1.83T1.10-1.30Standard distribution, general industrial transformersUSD 1,950-2,650
CRGO Economy0.35mm; B800 ≥ 1.78T1.30-1.50Cost-sensitive distribution, dry-type transformersUSD 1,650-2,200
CRNGO / CRNO Semi-processed0.35-0.50mm; isotropic loss2.5-3.5 (at 1.5T)Motor stators, small generators, ballastsUSD 950-1,400
CRNGO Fully-processed (low-loss)0.35mm; oriented-isotropic mix1.8-2.5 (at 1.5T)Premium motors, electric vehicle traction motors, premium generatorsUSD 1,400-2,200
Amorphous metal (Metglas type)~25 microns thickness0.20-0.35Premium energy-efficient distribution transformersUSD 4,800-7,500
Nanocrystalline (Vitroperm type)~20 microns thickness0.15-0.30Common-mode chokes, current transformers, EMI filteringUSD 8,500-15,000

Copper and aluminum conductor products

Conductor typeTypical specificationsConductivityBest applications
Copper foil (rolled)0.05-0.5mm thick; widths 50-1500mm≥101% IACS (high-purity)Foil-wound transformer windings, large generators
Copper strip (annealed)0.5-3mm thick; widths 10-300mm≥100% IACSWound transformer windings, busbar applications
Copper strip (bare or paper-wrapped)1-10mm thick; widths 5-100mm≥100% IACSPower transformer windings (oil-immersed), large machine windings
Copper enameled wire (round)0.05-3mm diameter; PEW/PEI/PAI insulation≥100% IACSRound-wire winding for transformers and motors
Copper enameled wire (rectangular)1-10mm × 1-5mm; PEW/PEI insulation≥100% IACSHigher-fill-factor windings for compact transformers
Aluminum strip (annealed, bare)0.5-3mm thick; widths 10-300mm~62% IACS (1350 alloy)Cost-sensitive distribution transformers, dry-type transformers
Aluminum foil (rolled)0.05-0.5mm thick; widths 50-1500mm~62% IACSFoil-wound dry-type distribution transformers (cost-driven)
Aluminum enameled wire (round)0.5-3mm diameter; PEW insulation~62% IACSCost-sensitive motor/transformer windings
Continuously transposed conductor (CTC)Multiple insulated copper strips bundled≥100% IACS effectiveLarge power transformer windings (lower eddy losses)

Material selection — copper vs aluminum economics

Aluminum-wound dry-type distribution transformers are the dominant choice for cost-sensitive distribution transformer applications (rural distribution, prefabricated substations, lower-tier markets). Copper-wound oil-immersed distribution transformers remain dominant for premium / urban / industrial applications. The volume and weight penalty of aluminum (15-25% larger transformer for same rating) is acceptable in many distribution applications where space is not critical. The specific economics of aluminum-vs-copper depend on current commodity pricing — copper-vs-aluminum price ratio fluctuates significantly. For OEM transformer manufacturers, dual-material capability (both copper-wound and aluminum-wound product lines) provides market flexibility.

CriterionCopperAluminumImplication
Resistivity1.68 µΩ·cm2.65 µΩ·cm (1350 alloy)Aluminum needs ~63% more cross-section for same resistance
Density8.96 g/cm³2.70 g/cm³Aluminum about 30% of copper density
Specific cost (per ton)USD 8,000-9,500USD 2,300-2,800Aluminum about 30% of copper price by weight
Cost per equivalent resistance (per kg basis × cross-section needed)Baseline 100%Approximately 50-60% of copperAluminum cost-saving for transformer windings is ~40-50%
Mechanical strengthHigherLower (needs careful joint design)Aluminum joints require special technique; bolted connections need anti-oxidation paste
Connection issuesEasy soldering / brazingRequires specific welding or compression jointsAluminum windings limit to specialized end-applications
Volume penaltySmaller transformer volume15-25% larger transformer for same ratingAluminum acceptable when space is not critical

Standard sizes and packaging

ProductStandard sizesPackaging unitContainer utilization
CRGO coil (mother coil)500-1200mm width × 0.23-0.35mm thick × 4-15 ton coil weightSteel-banded coil with edge protection~22-26 ton in 20' container
CRGO slit coil (transformer width)30-300mm width × 0.23-0.35mm × 1-5 ton coil weightSteel-banded coils stacked on pallets~22-26 ton in 20' container
CRGO sheets (cut to length)Custom sheet sizes; thickness 0.23-0.35mmBundled and strapped on pallets~22-26 ton in 20' container
CRNGO coil500-1200mm width × 0.35-0.50mm thickSteel-banded coil with edge protection~22-26 ton in 20' container
Copper foil (large rolls)50-1500mm width × 0.05-0.5mm thick × 50-500 kg rollCardboard core wrapped in plastic film~18-22 ton in 20' container
Copper strip (small rolls)10-300mm width × 0.5-3mm thick × 25-150 kg rollWooden spool or cardboard core~18-22 ton in 20' container
Aluminum strip / foilSizes similar to copper, lower densityCardboard core / wooden spool~6-8 ton in 20' container (volume-limited)

Pricing brackets — wholesale

Note: Electrical steel and copper pricing tracks underlying commodity (steel + electrical-grade premium for CRGO; LME copper for copper products) plus processing premium. Long-term contracts typically use index-based pricing where the material cost adjusts monthly with commodity index movement plus a fixed processing premium. For high-volume buyers, hedging the underlying commodity exposure may be appropriate.

Order tierTotal quantityDiscount vs spotContainer utilizationLead time
Sample / small OEM500 kg - 5 tonsSpot price + small premiumLCL15-25 days
Mid OEM transformer manufacturer15-50 tons / quarterSpot - 1-3%Partial 20' container25-40 days
Large OEM transformer manufacturer50-300 tons / quarterSpot - 3-7%Full 20' or 40' container35-60 days
National distributor / utility OEM500+ tons / quarterSpot - 5-10%; index pricing arrangementsMultiple containers45-90 days

Quality certification and testing

StandardApplies toTest requirements
GB/T 2521 / IEC 404-8CRGO grain-oriented electrical steelMagnetic loss test, dimensional accuracy, surface insulation
GB/T 2521.2 / IEC 404-8-4CRNGO non-grain-oriented electrical steelMagnetic loss test (isotropic), dimensional accuracy
ASTM A876 / A977Electrical steel for power transformersMagnetic property testing, dimensional
JIS C 2552 / C 2553Japanese electrical steel standardsMagnetic property testing
ASTM B187 / B49Copper foil and strip for electrical applicationsConductivity (% IACS), tensile strength, ductility, surface finish
ASTM B209 / B233Aluminum sheet and stripConductivity, mechanical properties
IEC 60317Enameled magnet wireInsulation thickness, breakdown voltage, thermal class
NEMA MW1000Magnet wire standards (US)Insulation properties, thermal endurance

Order workflow — electrical-materials procurement

View the full supplier profile, certifications, contact details, and complete product catalogue.

TransformerStrip — Chinese supplier of transformer-grade electrical materials. Cold-rolled grain-oriented (CRGO) silicon steel in Premium HiB / High-grade / Standard / Economy grades (0.23-0.35mm thickness, JIS / GB / IEC / AISI nomenclature support); non-grain-oriented (CRNGO / CRNO) silicon steel for motor and generator laminations; copper foil and strip for transformer windings (0.05-3mm thick, 5-1500mm width); copper enameled wire (round and rectangular, PEW/PEI/PAI insulation); aluminum strip and foil for cost-sensitive distribution transformers; amorphous metal cores (Metglas-type) for premium energy-efficient transformers; nanocrystalline cores for current transformers and EMI filtering. Mill test certificates per GB/T 2521 / IEC 404-8 / ASTM A876 / JIS C 2552. Slitting services available for transformer-width coils.

  • Application analysis — define exact specification per application (CRGO grade, thickness, width; or copper purity, thickness, width); establish quantity per quarter or annual demand
  • Specification clarification — for CRGO: grade (Premium / High-grade / Standard), thickness, width tolerance, edge condition (mill-edge / slit-edge), surface insulation type. For copper: purity (oxygen-free vs ETP), thickness, width, temper (annealed / hard), surface finish
  • Sample order — typically 50-500 kg per candidate spec; verify magnetic properties (CRGO: Epstein test for loss and B800), dimensional accuracy (thickness ±0.005mm typical, width ±0.05mm), surface quality (insulation continuity for CRGO; oxidation absence for copper)
  • Production trial — process sample into actual transformer or motor; verify performance vs spec; document any deviation from expected behavior
  • First commercial order — typically 15-50 tons depending on application; specify exact tonnage, packaging, and delivery schedule
  • Quality acceptance — every coil should ship with mill test certificate (chemistry, dimensional, magnetic for steel; conductivity for copper); incoming inspection on 5-10% of coils for verification
  • Series replenishment — typically monthly or quarterly orders aligned with production schedule; index-based pricing for long-term arrangements; safety stock typically 6-12 weeks of consumption

Frequently asked questions

Companion guide for power-electronics products that use transformer cores and copper windings.

Companion guide for electromagnetic materials — permanent magnets used alongside soft-magnetic electrical steel.

Companion guide for electrical components — contactors used downstream of transformers in distribution panels.

Source: Product images on this page are hosted on the manufacturer's official website (transformerstrip.com) and link directly back to that website. All product information was summarised from the supplier's public catalogue.

Brand mentions and trademark compliance: References to Tier-1 electrical-steel manufacturer brands (Nippon Steel, JFE Steel, ArcelorMittal, ThyssenKrupp, Posco, Baosteel, Wisco, Shougang) and copper-conductor brands (Wieland, Aurubis, Mitsubishi Materials, KME) are made for the sole purpose of describing functional benchmarks and supply-chain context. TransformerStrip is not authorized by, affiliated with, or endorsed by any of these brand owners. Products are aftermarket-fit cross-reference materials manufactured under TransformerStrip's own brand or buyer-private-label only.

Commodity pricing volatility: Electrical-grade silicon steel and copper conductor pricing track underlying commodities (HRC steel + electrical-grade premium for CRGO; LME copper for copper products) which exhibit significant price volatility. Long-term contracts should specify pricing structure (spot, index-based, fixed, or pass-through) explicitly to avoid disputes. For high-volume buyers, commodity hedging strategies may be appropriate.

Pricing & specifications: All price ranges, magnetic property figures, and tier definitions reflect general market observation and may not apply to specific orders. Real-world transformer performance depends on core design, winding technique, and assembly quality in addition to material specifications. Confirm current pricing, MOQ, lead time, and configuration directly with the supplier.

No middleman role: CifyChina provides supplier discovery and editorial content. All transactions occur directly between buyer and supplier through the contact channels published on the supplier's official website.

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