Contact UsIn transformer manufacturing, copper windings have traditionally dominated the market. However, with global copper prices remaining high, power-grid construction expanding into remote regions, and increasing demand for lightweight transformers in the renewable-energy sector, aluminum windings are evolving from an "alternative option" into a preferred solution.
In this trend, 1070 O temper aluminum strip has become one of the most noteworthy conductor materials for transformer coil windings, thanks to its ultra-high aluminum purity of more than 99.7% and excellent electrical conductivity.
Overview of 1070 O Temper Aluminum Strip
1070 aluminum strip belongs to the 1000-series pure aluminum family. With an aluminum content of no less than 99.7%, it is one of the highest-purity grades of commercial pure aluminum.
Compared with conventional 1050 aluminum strip, with aluminum content of ≥99.5%, and 1060 aluminum strip, with aluminum content of ≥99.6%, 1070 aluminum strip offers higher purity and lower impurity levels, such as silicon (Si) and iron (Fe). This results in better electrical conductivity and thermal conductivity.
"O" represents the annealed temper, also known as soft temper. The material undergoes a full annealing process to achieve its lowest strength and highest elongation. This temper gives the aluminum strip excellent flexibility and formability, allowing it to adapt easily to the bending, stretching, and layer-by-layer winding operations required during transformer coil production.
1070 O temper aluminum strip also offers good corrosion resistance, thermal conductivity, and weldability. It supports resistance welding and gas welding, meeting the multiple requirements for conductor materials in dry-type transformers and oil-immersed transformers.
Common names include:
1070 O Temper Aluminum Strip
1070 Soft Aluminum Strip
1070 Transformer Aluminum Strip
1070 Transformer Winding Aluminum Foil
1070 Aluminum Conductor Strip
1070 Annealed Aluminum Strip
1070 Electrical Aluminum Strip
High Conductivity 1070 Aluminum Strip
1070 O Temper Aluminum Strip for Transformer Winding
Key Advantages of 1070 Aluminum Strip for Transformer Windings
1.Good Electrical Conductivity
1070 aluminum has high purity and good electrical conductivity, making it suitable for low-voltage transformer foil windings and electrical conductors. Although aluminum has lower conductivity than copper and requires a larger cross-sectional area for the same current-carrying capacity, its lower density can significantly reduce winding weight.
2.Excellent Softness and Elongation
The O temper annealing process softens the aluminum strip and provides good elongation. It can withstand bending, tension, and forming deformation during winding without easily cracking. It is suitable for wide foil winding, continuous winding, and automated coil-winding processes, helping improve production efficiency and reduce scrap rates.
3.Stable Surface Quality for Insulation Processing
Transformer winding aluminum strip should have a flat and clean surface, free from oil stains, scratches, oxidation marks, burrs, and dents. A clean surface helps insulation paper, insulation film, or coating materials adhere properly, reducing the risk of local breakdown and turn-to-turn short circuits.
Degreased, low-oil, or customized surface-treatment options can be provided.
4.Lightweight Design and Cost Advantages
The density of aluminum is approximately 2.7 g/cm³, significantly lower than copper's 8.9 g/cm³. Under comparable electrical design conditions, aluminum windings can substantially reduce transformer weight. This makes them suitable for distribution transformers and large dry-type transformers.
Aluminum raw material also generally offers a cost advantage over copper, helping optimize conductor costs for large-volume projects.
5.Good Corrosion Resistance
Pure aluminum naturally forms a dense oxide film in air, providing resistance to normal atmospheric corrosion. With appropriate insulation and sealing design, it can maintain stable performance over long-term service.
Main Technical Specifications for 1070 Transformer Aluminum Strip
| Parameter | Specification Range |
| Alloy Grade | 1070 |
| Temper | O |
| Aluminum Content | ≥99.7% |
| Thickness | 0.08–3.00 mm |
| Width | 10–1500 mm |
| Electrical Conductivity | ≥62.7% IACS |
| Electrical Resistivity | ≤0.02825 Ω·mm²/m |
| Tensile Strength | 60–95 N/mm² |
| Elongation | ≥25% for 0.20–3.00 mm; ≥20% for 0.08–0.20 mm |
| Density at 20°C | 2.703 kg/dm³ |
| Burr Height | 0.01–0.03 mm |
| Coil Inner Diameter | 150 / 300 / 400 / 500 mm |
| Surface | Smooth, free from scratches and impurities |
| Edge Type | Slit edge, rounded edge, deburred edge, trimmed edge |
| Packaging | Moisture-proof paper, PE film, wooden pallets, wooden cases, or seaworthy export packaging |
| MOQ | 3 Tons |
Applications of 1070 O Temper Aluminum Strip in Transformers
1070 O temper aluminum strip is mainly used as a conductor material for transformer windings.
Typical applications include:
Distribution Transformers
For low-voltage windings in distribution transformers, aluminum strip winding structures can be used according to electrical design requirements.
Dry-Type Transformers
Dry-type transformers have relatively high requirements for winding structure and processing accuracy. 1070 O temper aluminum strip can be used in certain aluminum foil winding or strip winding structures.
Power Transformers
For some medium-sized and large transformers, aluminum conductors can be selected as winding materials according to design requirements.
Special Transformers
1070 O temper aluminum strip can also be used in specific electrical equipment and coil manufacturing applications based on customer requirements.
What Is the Difference Between 1070 O Temper Aluminum Strip, 1060 Aluminum Strip, and 1050 Aluminum Strip?
All 1000-series aluminum strips are industrial pure aluminum materials commonly used in electrical conductivity, electrical engineering, chemical processing, and forming applications. Among them, 1050, 1060, and 1070 are commonly used grades for transformer aluminum strips.
Comparison Item | 1050 Aluminum Strip | 1060 Aluminum Strip | 1070 Aluminum Strip |
| Aluminum Content | ≥99.5% | ≥99.6% | ≥99.7% |
| Electrical Conductivity | Good | Better | Superior |
| Ductility | Good | Good | Good |
| Material Cost | Relatively lower | Medium | Slightly higher |
| Typical Applications | General industry, decoration, electrical uses | Transformers, cables, electronics | High-conductivity transformer windings and electrical conductors |
For transformer windings requiring higher electrical conductivity and lower resistive loss, 1070 O temper aluminum strip is generally a more suitable choice. The final alloy selection should still be determined based on transformer capacity, design standards, winding cross-sectional area, and cost considerations.
Quality Requirements for Transformer Winding Aluminum Strip
Aluminum strip used for transformer windings must meet more than basic dimensional requirements. It should also provide suitable electrical performance, processing properties, and surface quality. The following parameters usually require close control.
Electrical Conductivity and Resistivity
Electrical conductivity directly affects winding resistance and load losses. For electrical-grade 1070 transformer aluminum strip, resistivity and conductivity should be controlled according to project standards or customer technical agreements. High-purity aluminum with low impurity content generally provides more stable electrical performance.
Thickness Tolerance
Thickness uniformity affects the actual cross-sectional area of the winding, interlayer height, and winding compactness. Excessive thickness variation may cause coil dimensional deviations, uneven local resistance, or variations in winding tension.
Width Tolerance
The strip width should match winding design dimensions and insulation-clearance requirements. For foil-wound transformers, high width precision helps ensure neat coil edges and reduces subsequent trimming work.
Edge Burr Control
Aluminum strip edge burrs are a critical concern in transformer winding production. Excessive burrs may puncture insulation paper or insulation film, increasing the risk of turn-to-turn short circuits and partial discharge.
Therefore, 1070 O temper aluminum strip for transformer applications generally requires smooth edges without sharp burrs, edge cracks, or obvious wavy edges. Deburred or rounded-edge processing can be provided as required.
Surface Cleanliness
Residual oil, dust, oxide spots, and indentation marks may affect insulation-material bonding and subsequent processing quality. For projects requiring laminated insulation film or special processing, degreased or low-oil aluminum strip is recommended.
Flatness and Coil Shape
Good flatness helps improve the stability of automated winding equipment. Aluminum strip should be free from obvious camber, waviness, warping, edge buckling, telescoping, and loose winding.
Why Choose Our 1070 O Temper Aluminum Strip?
Our 1070 O temper aluminum strip is designed specifically for transformer winding applications and offers the following advantages:
1.Guaranteed Purity
Aluminum content is consistently controlled at more than 99.7%, ensuring electrical conductivity and corrosion resistance from the raw-material stage.
2.Excellent Electrical Conductivity
Electrical conductivity is guaranteed at ≥62.7% IACS, with typical actual values reaching 63%. This meets the winding design requirements of high-efficiency transformers.
3.Precision Edge Quality
Precision slitting and edge-rounding processes are used to control burr height within 0.01–0.03 mm. This effectively protects insulation integrity and reduces the risk of turn-to-turn short circuits.
4.Clean and Smooth Surface
The surface is smooth and free from scratches and impurities, ensuring good adhesion to insulating materials and stable electrical performance.
5.Flexible, Customizable Specifications
Thickness ranges from 0.08 to 3.00 mm, while width ranges from 10 to 1500 mm. Width, coil inner diameter, and coil weight can be customized according to transformer design requirements.
6.Reliable Supply Capacity
With multiple aluminum strip slitting lines, we support orders ranging from 5 to 2,000 tons, with stable lead times and worldwide export capability.
