Market Insight: Aluminium Sheet Coil

Market Analysis: Transformer Strip/Foil (Aluminum/Copper)

The global demand for aluminum sheet coil in transformer manufacturing has grown steadily over the past two decades, driven by the expansion of power infrastructure, renewable energy integration, and the pursuit of lightweight, cost-effective electrical systems. Aluminum, particularly in the form of precision-rolled strip and foil, serves as a critical material in both distribution and power transformers, primarily as winding conductors. While copper remains the traditional choice for high-conductivity applications, aluminum offers a compelling alternative due to its favorable conductivity-to-weight ratio, corrosion resistance, and lower material cost. As grid modernization accelerates across Asia, Africa, and Latin America, aluminum-based transformer windings are increasingly specified in medium-voltage distribution systems where weight reduction and lifecycle cost efficiency are prioritized.

The industrial demand for aluminum sheet coil in this sector is closely tied to electrical conductivity, surface integrity, dimensional accuracy, and mechanical uniformity. Transformer windings require materials that can withstand high electromagnetic stresses, thermal cycling, and prolonged operational loads. Substandard aluminum strip—characterized by inconsistent thickness, surface defects, or impurity segregation—can lead to localized heating, insulation breakdown, and premature transformer failure. Therefore, the performance and reliability of aluminum transformer windings are directly correlated to the metallurgical and dimensional quality of the supplied coil.

At Luoyang Xinzhaohe Aluminum CO., Ltd, with over 20 years of specialized production experience, we emphasize stringent process control from billet homogenization through hot rolling, cold rolling, and final annealing. Our aluminum strip for transformer applications is typically produced in alloys 1060, 1070, and 1350, meeting ASTM B419 and IEC 60164 standards. These high-purity alloys ensure minimum electrical resistivity, while our precision rolling technology maintains thickness tolerances within ±0.01 mm and achieves surface roughness values below 0.5 μm Ra. Such specifications are essential for uniform winding tension, dielectric stability, and efficient heat dissipation in transformer cores.

Furthermore, the shift toward energy-efficient transformers (e.g., amorphous metal and high-efficiency silicon steel designs) has increased the demand for compatible, high-quality aluminum conductors. These advanced transformers operate under tighter thermal margins, making material consistency non-negotiable. Any variation in strip flatness or edge burr formation can compromise winding integrity during high-speed coil winding processes.

Supply chain reliability and traceability are also critical in this sector. Transformer manufacturers require consistent batch-to-batch performance and full material certification, including chemical composition, mechanical properties, and electrical conductivity test reports. As a vertically integrated producer, Luoyang Xinzhaohe Aluminum ensures end-to-end quality monitoring, from raw material sourcing to final packaging, enabling long-term supply stability for OEMs and tier suppliers in the power transmission and distribution industry.

Technical Specs: Aluminium Sheet Coil

Technical Specifications for Precision Aluminum Sheet Coil in Transformer Applications

Luoyang Xinzhaohe Aluminum Co., Ltd leverages 20+ years of metallurgical expertise to deliver aluminum sheet coil engineered specifically for transformer strip and foil applications. Our stringent technical specifications ensure compatibility with high-efficiency transformer manufacturing, emphasizing dimensional precision, edge integrity, and electrical performance. Critical parameters are rigorously controlled through advanced cold rolling, precision slitting, and inline quality monitoring systems. The following table details mandatory specifications for aluminum sheet coil supplied to the transformer industry.

Precision slitting at ±0.002 mm width tolerance is non-negotiable for transformer strip applications. This tolerance is achieved through servo-driven tension control and hardened tungsten carbide rotary slitters, eliminating micro-tearing and ensuring edge parallelism. Deviations beyond this threshold induce uneven magnetic flux, increasing core losses by up to 8% in stacked laminations. Burr formation is mitigated via proprietary edge-trimming protocols and real-time laser profilometry, restricting burr height to ≤5 μm. Uncontrolled burrs compromise interlayer insulation, accelerating dielectric failure in wound components.

Conductivity of ≥61.0 % IACS (equivalent to 0.02826 μΩ·m resistivity) is validated per ASTM E1004 using eddy current testing on 100% of production lots. This benchmark exceeds IEC 60162 requirements for electrical aluminum, directly reducing no-load losses in transformers. Impurity control—particularly iron (<0.35%) and silicon (<0.25%)—is maintained through triple-refined ingot casting and degassing, as trace elements elevate resistivity. Surface cleanliness adheres to Ra ≤0.4 μm, preventing air gaps in laminated cores that degrade thermal conductivity.

All coils undergo 100% inline eddy current scanning for subsurface defects and are supplied with certified mill test reports including conductivity, mechanical properties, and dimensional conformance data. These specifications reflect Luoyang Xinzhaohe’s commitment to enabling transformer manufacturers to achieve IEC 60076-1 efficiency class targets through metallurgical precision. Non-compliance with any parameter necessitates automatic quarantine per our AS9100-aligned quality management system.

Factory Tour: Manufacturing

Manufacturing Process of Aluminum Sheet Coil at Luoyang Xinzhaohe Aluminum Co., Ltd

The production of high-performance aluminum sheet coil for transformer strip and foil applications at Luoyang Xinzhaohe Aluminum Co., Ltd follows a tightly controlled, multi-stage manufacturing sequence designed to ensure dimensional accuracy, surface integrity, and consistent metallurgical properties. With over two decades of specialized experience in non-ferrous rolling and slitting technologies, our process integrates advanced cold rolling techniques with precision finishing and rigorous quality control to meet the demanding requirements of power and electronic transformer systems.

The process begins with cold rolling, where pre-annealed aluminum ingots or hot-rolled slabs are fed into precision cold rolling mills. These mills operate under computer-controlled reduction schedules to achieve target thicknesses, typically ranging from 0.1 mm to 3.0 mm, depending on the application. Cold rolling enhances the mechanical properties of the aluminum by increasing tensile strength and improving surface flatness through work hardening. The rolling parameters—including roll gap, rolling speed, and interpass tension—are continuously monitored and adjusted in real time to maintain uniform thickness tolerance within ±0.005 mm across the coil width. Lubrication and cooling systems utilize high-purity synthetic oils to minimize thermal distortion and prevent surface defects such as scratches or roll marks.

Following cold rolling, the aluminum coils undergo precision slitting, a critical operation for transformer strip production where width consistency directly impacts winding performance and core efficiency. Using servo-driven slitting lines equipped with high-precision circular knives, the master coils are longitudinally cut into narrow strips, typically between 10 mm and 100 mm in width. The slitting process is optimized to produce burr-free edges and maintain tight width tolerances of ±0.1 mm. Tension control and automatic edge guiding systems ensure minimal coil wandering and consistent strip geometry throughout the length of the coil.

Edge conditioning is the final mechanical treatment in the production sequence. The slit edges are subjected to brushing or edge rolling to remove micro-burrs and smooth any residual irregularities that could compromise insulation integrity during transformer winding. This step is essential for preventing dielectric breakdown and ensuring long-term reliability in high-voltage applications.

Throughout the manufacturing process, in-line and final quality control inspections are conducted at multiple stages. These include surface defect detection via high-resolution optical scanners, thickness profiling using laser micrometers, edge quality assessment under stereo microscopy, and mechanical testing for tensile strength, elongation, and bend performance. All coils are also subjected to eddy current testing to detect subsurface flaws. Final inspection reports, including coil traceability data and compliance with GB/T 3880 or ASTM B209 standards, are provided with each shipment.

This integrated approach to aluminum sheet coil manufacturing ensures that Luoyang Xinzhaohe delivers products with exceptional consistency, surface quality, and electrical performance for transformer and foil applications.

Packaging & Logistics

Export Packaging Specifications for Aluminum Transformer Strip and Foil Coils

Luoyang Xinzhaohe Aluminum Co., Ltd. implements rigorously engineered export packaging protocols for aluminum transformer strip and foil coils to ensure integrity during global sea freight. With over 20 years of metallurgical and supply chain expertise, our system mitigates corrosion, mechanical damage, and moisture ingress—critical for thin-gauge electrical materials where surface purity and dimensional stability are non-negotiable. All packaging adheres to ISO 9001 standards and complies with international maritime regulations, including IMDG Code requirements for non-hazardous cargo.

Pallet Construction and Coil Securing
Coils are mounted on custom-engineered wooden pallets fabricated from ISPM 15-certified, kiln-dried (KD) softwood. Pallet dimensions align precisely with coil outer diameters (OD) and widths, featuring a minimum load-bearing capacity of 5,000 kg to prevent structural deformation. Each pallet incorporates recessed base plates to stabilize the coil core and eliminate lateral shift. Steel strapping (minimum 19 mm width, 0.8 mm thickness) is applied at 800–1,000 kgf tension across the coil face, anchored to pallet stringers via tension-lock buckles. Corner protectors of high-density polyethylene (HDPE) shield edges from handling impacts, while external steel angle brackets (12 mm thickness) welded to the pallet frame prevent coil rotation during vessel motion.

Multi-Layer Moisture Barrier System
A triple-layer moisture-proof enclosure is mandatory for all sea shipments. The innermost layer consists of 100 μm aluminum foil laminated to polyethylene, directly wrapped around the coil to block vapor transmission. This is overlaid with 150 μm metallized polyester film, heat-sealed at all seams to achieve a water vapor transmission rate (WVTR) below 0.5 g/m²/day. The outer layer utilizes 200 μm high-density polyethylene (HDPE) stretch film, machine-applied with 70% overlap to ensure pinhole-free coverage. Critical sealing points—including core ends and coil edges—are reinforced with butyl rubber tape to eliminate capillary pathways. Desiccant packs (silica gel, 300 g/m³ cargo volume) and humidity indicator cards (range 10–90% RH) are enclosed within the barrier to monitor conditions.

Verification and Documentation
Pre-shipment validation includes vacuum decay testing of the sealed envelope to confirm leak integrity (< 5 Pa/min pressure loss). Relative humidity inside the barrier is verified at ≤ 40% RH prior to dispatch. All packaging components are traceable via batch numbers linked to the material test report (MTR). The packing list explicitly details pallet dimensions, strapping tension, desiccant quantity, and barrier film specifications to facilitate customs clearance and buyer quality audits. This end-to-end protocol has maintained a 99.8% damage-free delivery rate across 12,000+ TEUs since 2015, even on routes with >60-day transits through tropical humidity zones.

Our packaging is not merely protective—it is an extension of our metallurgical commitment to delivering transformer-grade aluminum with uncompromised surface quality. By integrating material science with freight logistics, we eliminate the root causes of coil degradation, ensuring your production line receives material ready for immediate slitting and lamination.

Sourcing from Luoyang Xinzhaohe

Partner with Luoyang Xinzhaohe Aluminum CO., Ltd for Precision Transformer Strip and Foil Solutions

With over two decades of specialized manufacturing experience, Luoyang Xinzhaohe Aluminum CO., Ltd stands as a trusted leader in the production of high-precision aluminum and copper transformer strips and foils. Located in the industrial hub of Luoyang, China, our vertically integrated facility combines advanced metallurgical engineering with rigorous quality control to deliver products that meet the exacting demands of global power transmission and distribution markets.

Our factory operates a fully automated production line capable of processing aluminum and copper into precision strips ranging from 0.1 mm to 3.0 mm in thickness, with widths up to 1600 mm. Utilizing state-of-the-art cold rolling mills, tension-leveling systems, and continuous annealing lines, we ensure consistent mechanical properties, superior surface finish, and tight dimensional tolerances. All materials are processed under controlled atmospheric conditions to prevent oxidation and maintain metallurgical integrity, critical for high-efficiency transformer performance.

Material traceability and process control are central to our manufacturing philosophy. We source high-purity aluminum (1060, 1070, 1100, 3003, 8011) and electrolytic tough pitch (ETP) copper, each batch verified through optical emission spectroscopy (OES) and inductively coupled plasma (ICP) analysis. Our in-house metallurgical laboratory conducts comprehensive testing, including tensile strength, elongation, grain size analysis, and eddy current inspections, ensuring compliance with international standards such as GB/T, ASTM, and IEC.

We specialize in customized solutions for wound-core and stacked-core transformer manufacturers, offering tailored temper conditions (O, H14, H16, H18), edge trimming precision, and coil weight optimization to reduce winding waste and improve core stacking efficiency. Our aluminum transformer strips are engineered to deliver low iron loss, high permeability, and excellent DC resistance, directly contributing to transformer energy efficiency and reduced no-load losses.

Environmental and operational sustainability is embedded in our operations. Our facility is ISO 9001:2015 and ISO 14001:2015 certified, with energy recovery systems integrated into annealing furnaces and closed-loop cooling circuits minimizing resource consumption. We maintain strategic raw material inventory buffers to ensure uninterrupted supply, supported by a logistics network capable of FOB, CIF, and DDP delivery terms worldwide.

As a technical partner, we provide full documentation packages, including mill test certificates (MTCs), material compliance reports, and process validation data, ensuring seamless integration into our clients’ quality assurance workflows. Our engineering team supports collaborative development for next-generation transformer designs, including amorphous metal-compatible strip configurations and ultra-thin foil laminations.

For sourcing professionals and OEMs seeking a reliable, high-capacity supplier of transformer-grade aluminum and copper strips, Luoyang Xinzhaohe offers unmatched technical depth, production scalability, and product consistency.

Contact us today to discuss your specifications and receive a technical datasheet and sample coil.

Cathy Zhang
International Sales Manager
Luoyang Xinzhaohe Aluminum CO., Ltd
Email: cathy@transformerstrip.com