Electrical soft copper brush wire
Electrical soft copper brush wire is a flexible conductive wire used in rotating electrical equipment such as motors and generators to connect brushes to external circuits. Its primary function is to transmit current from the fixed portion to the rotating portion, ensuring the proper operation of the equipment. Made from high-purity electrolytic copper (copper content of 99.95% or more), this wire is twisted together from multiple fine copper strands. It exhibits excellent conductivity, flexibility, and wear resistance, and can withstand the high-frequency vibration and friction associated with motor operation. It is widely used in industrial, automotive, and traction motors.
The production of electrical soft copper brush wire requires numerous meticulous steps to ensure its performance and quality. First, high-purity electrolytic copper rods are used as raw material. Through the wire drawing process, the copper rods are drawn into fine copper wires with a diameter of 0.1-0.5 mm. Special lubricants are used during the drawing process to reduce friction and surface damage. The drawing speed and die precision are carefully controlled to ensure uniform wire size and a smooth surface. Subsequently, the strands are twisted together using methods such as regular twisting and bundle twisting. The twist pitch and number of strands are determined based on product specifications and usage requirements, typically ranging from 7 to 1,000. During the twisting process, uniform stress is applied to each strand to prevent loose strands and wire breakage. After twisting, the wire undergoes annealing, a critical step in maintaining its flexibility. The wire is heated to 300-500°C under an inert gas atmosphere, held at this temperature for a period of time, and then slowly cooled to eliminate internal stresses generated during the drawing and twisting process, thereby improving the wire’s flexibility and conductivity. After annealing, the brush wire undergoes surface treatments such as tinning or silvering. Tinning improves welding performance and corrosion resistance, while silvering further enhances conductivity and wear resistance, meeting the requirements of high-end equipment. Finally, after inspection and packaging, the finished electrical soft copper brush wire must meet standard specifications for dimensional accuracy, conductor resistance, and flexibility.
Electrical soft copper brush wire offers a range of performance characteristics tailored to its operating environment. First, its core advantage is its excellent electrical conductivity, exceeding 95% IACS. This allows for efficient current transmission, reduces energy loss, and ensures the operating efficiency of motors and other equipment. Second, its excellent flexibility allows it to bend freely during motor rotation, adapting to brush movement and vibration. The bend radius can be as small as five times the wire diameter, and it resists breakage after repeated bending. Third, its high wear resistance ensures its longevity from contact and friction with brushes. The wear resistance can be enhanced by selecting the appropriate copper wire diameter and twisting method. Fourth, its fatigue resistance allows it to withstand long-term vibration and bending, with a fatigue life of over 100,000 cycles. Fifth, its excellent weldability facilitates connection to other conductive components. Tinned brush wire offers higher weld strength and more reliable connections.
Electrical soft copper brush wire is widely used in a wide range of applications. In industrial motors, such as asynchronous and synchronous motors, brush wire connects the brushes to the motor’s lead wires, directing current to the rotor windings and enabling motor rotation. In automotive motors, such as starter motors and generators, brush wires must withstand the vibration and temperature fluctuations of the vehicle during operation to ensure reliable operation. In traction motors, such as those used in locomotives and subway cars, brush wires must withstand high currents and frequent vibrations, requiring high wear and fatigue resistance. In generators, brush wires transmit the current generated by the generator from the rotor to the external circuit, serving as a critical channel for electrical energy output. Other rotating electrical equipment, such as power tools and machine tool spindle motors, also rely on electrical soft copper brush wires for connection. With the development of the motor industry and improvements in equipment performance, the performance requirements for electrical soft copper brush wires are becoming increasingly stringent.
Industry trends indicate that the production of soft copper brush wire for electrical applications is moving toward high purity, fine diameter, and multifunctionality. To enhance conductivity and flexibility, the use of high-purity copper (99.99% copper content or higher) is increasing. Optimizing the smelting and purification processes reduces impurities and improves wire performance. The trend is towards fine-diameter copper wire, with ultra-fine copper wire under 0.05 mm currently available. Twisting multiple strands makes the brush wire more flexible and adaptable to more complex installation environments. Progress has been made in the development of multifunctional brush wires, such as flame-retardant and high- and low-temperature-resistant wires, expanding their applications in specialized environments. Flame-retardant wires delay combustion in fire situations, improving equipment safety; high- and low-temperature-resistant wires maintain stable performance in environments ranging from -50°C to 150°C. Furthermore, the industry is promoting automation and intelligentization of production processes, improving production efficiency and product quality consistency through the introduction of online inspection systems and automated twisting equipment. In the future, with the rapid development of new energy vehicles, high-end equipment and other industries, the demand for high-performance electrical soft copper brush wire will continue to grow, driving the industry to make more breakthroughs in material research and development, process innovation and other aspects.
