Aluminum-magnesium alloy wire for cable shielding
Aluminum-magnesium alloy wire for cable shielding is an aluminum-based, magnesium-added alloy wire primarily used in cable shielding. By confining electromagnetic fields to the cable interior or preventing external electromagnetic interference, it ensures stable signal or power transmission. It is widely used in communications cables, power cables, rail transit cables, and other fields. Its diameter typically ranges from 0.1 to 2 mm, and its magnesium content is generally 0.5% to 1.5%, forming an Al-Mg alloy. This alloy retains the lightweight and conductivity of aluminum while enhancing its strength and corrosion resistance through solid solution strengthening with magnesium, making it suitable for the complex environments encountered during cable installation and use.
The production process for aluminum-magnesium alloy wire for cable shielding involves key steps, including alloy smelting, ingot casting, hot rolling, cold drawing, and annealing. First, high-purity aluminum ingots (≥99.7%) and magnesium ingots are heated to 720-760°C in a melting furnace according to the alloy composition requirements. Electromagnetic stirring is used to evenly distribute the magnesium, keeping the magnesium content within ±0.05%. Refining agents are added to remove hydrogen and impurities to ensure melt purity. A semi-continuous casting process is used to produce round ingots with diameters of 80-120 mm. The cooling rate is controlled during the casting process to ensure uniform distribution of alloying elements and avoid segregation and porosity. Hot rolling heats the ingots to 400-500°C and then rolls them through multiple passes to form wire billets with diameters of 5-10 mm. The reduction and speed are controlled, with each pass achieving a reduction of ≤30%, ensuring a dense microstructure and a smooth surface. Cold drawing is the core process for obtaining high-precision wire. The wire blank is drawn through multiple drawing dies, with a reduction rate of 10%-20% per pass, gradually reaching the target diameter. A water-soluble lubricant is used for cooling and lubrication to prevent surface scratches on the wire, and the diameter tolerance is controlled within ±0.01 mm. Annealing is performed according to performance requirements, heating the wire to 250-350°C, holding for 1-2 hours, and then air-cooling. This adjusts the material’s hardness and toughness to achieve a tensile strength of 180-250 MPa and an elongation of 10% or more, meeting the braiding and winding requirements of the shield layer.
The performance advantages of aluminum-magnesium alloy wire for cable shielding make it significantly competitive in the shielding field. First, it has high strength and light weight. The tensile strength of Al-Mg alloy wire is 1.5-2 times that of pure aluminum wire. It can withstand the stretching and bending forces during cable laying and reduce the risk of wire breakage. At the same time, the density is only 2.7g/cm³, which is more than 60% lighter than copper, reducing the overall weight of the cable and facilitating transportation and laying. Second, it has good conductivity and shielding effect. The conductivity can reach more than 50% IACS, which can effectively conduct interference current. The shielding layer formed by braiding or winding has a shielding effectiveness of ≥80dB for electromagnetic waves, ensuring the quality of signal transmission, especially in high-frequency communications. Third, it has excellent corrosion resistance. The addition of magnesium and the dense oxide film formed on the surface make the alloy wire more corrosion-resistant than pure aluminum wire in humid, salt spray and other environments. The service life can reach more than 20 years in coastal areas, underground pipelines and other scenarios. Fourth, it has good processing performance. The annealed alloy wire has appropriate hardness and flexibility, and can be easily braided, twisted and other processes. The braiding density can reach 90%. The above ensures the continuity of the shielding layer; fifthly, the cost advantage is obvious. Compared with copper alloy shielded wire, the raw material cost of aluminum-magnesium alloy wire is reduced by more than 40%, and its light weight reduces transportation and installation costs, making it more cost-effective.
Aluminum-magnesium alloy wire for cable shielding is widely used in various applications. In the communications cable sector, aluminum-magnesium alloy wire is often used for the metal reinforcement core and shielding layer of optical cables. For example, the shielding layer of ADSS optical cables uses alloy wires with a diameter of 0.5-1 mm. These wires are twisted to form a protective layer and also shield against electromagnetic interference. In the power cable sector, the metal shielding layer of medium- and high-voltage cross-linked cables uses aluminum-magnesium alloy wire. The insulation layer is wrapped or braided to conduct fault currents to the grounding system, protecting the cable safety. In the rail transit sector, subway and light rail vehicle cables need to be vibration-resistant and anti-interference. Braided shielding layers of aluminum-magnesium alloy wire with a diameter of 1-2 mm are used to balance strength and shielding effectiveness. In the automotive sector, high-voltage cables for new energy vehicles use aluminum-magnesium alloy wire shielding to reduce electromagnetic interference generated by motors and inverters, ensuring the normal operation of on-board electronic equipment. In the industrial sector, control cables for automation equipment use fine-diameter (0.1-0.5 mm) aluminum-magnesium alloy wire braided shielding layers to accommodate installation requirements in confined spaces.
Industry trends indicate that aluminum-magnesium alloy wire for cable shielding is trending toward high strength, high shielding effectiveness, and a thin diameter. By optimizing alloy composition, such as adding trace amounts of rare earth elements (such as scandium and zirconium), tensile strength can be increased to over 300 MPa while maintaining conductivity, making it suitable for long-span, high-tension installations. High-shielding alloy wires are being developed, with nickel plating or conductive coatings increasing shielding effectiveness to over 90 dB, meeting the demands of high-end communications and military applications. Continuous advancements in fine-diameter alloy wire production technology have enabled the stable production of wires under 0.1 mm, suitable for high-density braiding and enhancing the density of the shielding layer. Furthermore, environmentally friendly production processes are being promoted, using chromium-free passivation and recycled aluminum raw materials to reduce environmental pollution and raw material costs during the production process. With the rapid development of 5G communications, rail transit, and new energy vehicles, demand for high-performance cable shielding materials will continue to grow, driving further progress in material research and development, process innovation, and application expansion for aluminum-magnesium alloy wire for cable shielding.
