Aluminum and aluminum alloy flat wire for electrical use
Aluminum and aluminum alloy flat wire for electrical applications is an aluminum-based conductive material with a rectangular or flat cross-section. It is widely used in the winding manufacturing of electrical equipment such as transformers, reactors, and motors. Due to its lightweight, excellent conductivity, and cost advantages, aluminum and aluminum alloys have become an important alternative to copper flat wire. Available in a variety of specifications, widths typically range from 4 to 50 mm and thicknesses from 1 to 10 mm, depending on the power requirements of the equipment. Materials commonly used include aluminum and aluminum alloy grades such as 1060, 3003, and 6063. Pure aluminum flat wire prioritizes conductivity, while aluminum alloy flat wire balances strength and conductivity, meeting the requirements of diverse operating conditions.
The production process for electrical aluminum and aluminum alloy flat wire involves key steps, including smelting and casting, hot rolling, cold forming, annealing, and surface treatment. First, aluminum ingots and alloying elements are heated to 700-750°C in a smelting furnace to melt, depending on the product grade. Degassing and slag removal processes are used to reduce hydrogen content and non-metallic inclusions, ensuring melt purity. The molten aluminum is then cast into rectangular ingots, the dimensions of which must be compatible with subsequent rolling processes. The ingots are then hot-rolled to slabs with a thickness of 10-20 mm at a temperature of 350-500°C. Multiple rolling passes eliminate as-cast structural defects and refine the grain size. Cold rolling is a key process in determining the dimensional accuracy of flat wire. Hot-rolled flat slabs are rolled using a multi-roll cold rolling mill, with a reduction rate of 15%-30% per pass. The thickness is gradually reduced to the target size, while maintaining a width tolerance within ±0.1 mm, a thickness tolerance within ±0.05 mm, and a surface roughness Ra ≤ 1.6 μm. Flat wire that requires bending and forming undergoes annealing. This involves heating to 280-350°C under inert gas, holding for 1-3 hours, and then slowly cooling to reduce the material’s hardness, improve its plasticity, and achieve an elongation of at least 15%. Finally, surface treatment is applied according to the intended use, such as varnishing or anodizing. The varnishing insulation layer is 0.05-0.2 mm thick and must pass a breakdown voltage test. Anodizing forms a dense oxide film, enhancing corrosion resistance.
The performance characteristics of aluminum and aluminum alloy flat wire for electrical use give it significant advantages in electrical equipment. First, it offers high cost-effectiveness. Aluminum’s density is only about one-third that of copper, making it lighter with comparable electrical conductivity. Furthermore, its raw material cost is lower than copper, significantly reducing equipment manufacturing costs. It’s particularly suitable for weight- and cost-sensitive equipment such as large transformers and reactors. Second, it offers excellent electrical conductivity. Pure aluminum flat wire has a conductivity of over 61% IACS, while 3003 aluminum alloy flat wire has a conductivity of approximately 55% IACS. While lower than copper, this can be compensated for by increasing its cross-section, meeting the electrical conductivity requirements of medium- and low-voltage electrical equipment. Third, it offers excellent formability. Annealed flat wire can be bent, sheared, and wound, fitting snugly into core slots, improving the winding fill factor and reducing equipment size. Fourth, it offers excellent corrosion resistance. A dense oxide film easily forms on the aluminum surface, effectively resisting corrosion in dry environments. Alloying treatments for aluminum alloy flat wires, such as 6063 , further enhance their corrosion resistance, making them suitable for humid or lightly polluted environments. Fifth, it offers excellent thermal conductivity, with a thermal conductivity of approximately 200W/(m · K). , which can dissipate the heat generated by the winding in time to avoid overheating of the equipment.
Aluminum and aluminum alloy flat wire for electrical applications is widely used. In power transformers, aluminum and aluminum alloy flat wire are commonly used for the low-voltage windings of medium and low-voltage transformers. By properly designing cross-sectional dimensions, they ensure conductivity while reducing cost and weight. For example, 10kV distribution transformers often use flat wire with a width of 20-30 mm and a thickness of 3-5 mm for the low-voltage windings. In reactors, smoothing reactors and series reactors are wound with aluminum flat wire, leveraging its lightweight properties to reduce the load on the installation foundation. In motor manufacturing, aluminum flat wire can be used for the stator windings of small and medium-sized asynchronous motors, particularly in light-load equipment such as fans and water pumps. In equipment such as welding machines and power transformers, aluminum and aluminum alloy flat wire is insulated with varnish to create a multi-layer insulation structure that meets the insulation requirements of the equipment. With the development of the new energy industry, the use of aluminum and aluminum alloy flat wire in equipment such as photovoltaic inverters and wind turbine converters is also increasing, thanks to its lightweight advantages, adapting to the installation environments of new energy equipment.
Industry trends indicate that aluminum and aluminum alloy flat wire for electrical applications are trending toward high conductivity, high strength, and thin cross-sections. By developing new aluminum alloy materials, such as aluminum-rare earth alloys with trace amounts of rare earth elements, electrical conductivity can be increased to over 63% IACS while maintaining strength, narrowing the performance gap with copper. An online continuous annealing process precisely controls temperature and cooling rate, resulting in more uniform and stable flat wire performance. Thin-section flat wires are being developed, with widths as small as 4 mm and thicknesses under 1 mm, suitable for miniaturized, high-density winding electrical equipment, such as new energy vehicle drive motors. Surface treatment technology is also continuously evolving, with environmentally friendly water-based insulating varnishes gradually replacing traditional solvent-based varnishes, reducing volatile organic compound emissions and raising the insulation layer’s temperature resistance from Class B (130°C) to Class F (155°C) and even Class H (180°C), enabling it to withstand higher-temperature operating environments. In the future, with the increasing requirements for energy conservation, emission reduction and lightweighting, the proportion of electrical aluminum and aluminum alloy flat wire used in electrical equipment will further increase, driving the industry to achieve greater breakthroughs in material research and development, process optimization and performance improvement.
