Copper coil: a metal coil that combines high functionality and continuous processing

Copper coil is made from pure copper (≥99.5%) or copper alloys (with added elements such as zinc, tin, and nickel), continuously hot-rolled and cold-rolled before being coiled into a disc-shaped profile. Its core value lies in "functionality preservation + efficient processing"—it inherits the excellent electrical and thermal conductivity and ductility of copper sheet while offering the advantages of on-demand unwinding and automated continuous production. This solves the problems of low efficiency and high loss associated with splicing individual copper sheets. It is widely used in applications requiring batch processing, such as electronics, heat dissipation, and decorative building materials. It is an "efficient precursor" to copper sheet (most precision copper sheet components are cut and processed from copper coils). ​

Based on its core attributes, it can be further categorized: by material composition, it can be divided into pure copper coil and alloy copper coil. Pure copper coils (such as grades T2 and T3) have a copper content of ≥99.9%, an electrical conductivity of approximately 98% IACS, and a thermal conductivity of 401W/(m・K). Their performance is comparable to that of pure copper sheet, making them suitable for continuous processing applications requiring high electrical and thermal conductivity (such as lithium battery tabs). Alloy copper coils are further categorized by composition: Brass coils (copper-zinc alloys, such as H62, containing 62% copper) are stronger than pure copper and easier to roll, costing only 1/2-2/3 of pure copper coils. They are the most widely used type of copper coil (e.g., decorative parts and general conductive components). Bronze coils (copper-tin alloys, such as QSn6.5-0.1) offer excellent wear resistance and are suitable for continuous processing of mechanical wear-resistant parts (e.g., bearing bushing coils). White copper coils (copper-nickel alloys, such as B10, containing 10% nickel) offer excellent seawater and low-temperature resistance and are used for continuous forming of marine engineering components (e.g., ship piping coils). Based on the processing technology, copper coils are divided into hot-rolled copper coils (thickness 3-20mm, rough surface, good toughness, coil weight 10-30 tons, suitable for rough processing continuous production lines) and cold-rolled copper coils (thickness 0.1-5mm, smooth surface, high dimensional accuracy, tolerance ±0.01mm, coil weight 5-15 tons, used for precision continuous stamping/cutting). Its core features focus on "dual excellence in functionality and efficiency": First, its functionality is identical to that of copper sheet, while its electrical and thermal conductivity far exceeds that of carbon steel coils and stainless steel coils (pure copper coils have a conductivity 20 times that of carbon steel coils and 30 times that of stainless steel coils). Its ductility supports continuous stretching (for example, cold-rolled pure copper coils can be drawn into 0.01mm thin strips). Brass coils appear golden yellow, while pure copper coils appear rose gold, eliminating the need for secondary coating. Second, processing efficiency is significantly improved, with a single coil capable of continuous feeding for several hours. For example, electronics factories using cold-rolled pure copper coils to process electrical terminals can achieve a daily output 4-6 times higher than that of single copper sheet processing. Furthermore, the coil cutting loss rate (≤1.5%) is much lower than that of single copper sheet (loss of 5%-8%). Third, cost adaptability is flexible. Although the unit price of pure copper coils is 12-15 times that of carbon steel coils and 4-5 times that of stainless steel coils, the cost of copper coils is significantly higher than that of single copper sheet processing. times, but the cost of brass coils is only 1/2 of that of pure copper coils, which can meet mid- and low-end functional requirements. Continuous processing eliminates the splicing process, reducing the overall production cost by 20%-30%. Fourthly, it has strong adaptability and can be linked with stamping, cutting, and bending equipment through the uncoiler to achieve "coil-finished product" integrated production, which is especially suitable for batch manufacturing of standardized components. ​

Application scenarios cover continuous processing and high-performance demanding fields: In the electronics and electrical sector, cold-rolled pure copper coils are used for continuous stamping of electrical busbars and lithium battery tabs, while brass coils are used for continuous cutting of connector terminals and switch contacts. In the thermal conductivity and heat dissipation sector, cold-rolled pure copper coils are continuously processed into LED heat sinks and computer CPU thermal pads, while brass coils are used for continuous forming of automotive radiator cooling belts. In the architectural decoration sector, brass coils are continuously bent into decorative moldings and ceiling keels, while pure copper coils are oxidized and continuously cut into retro-style decorative panels. In the machinery manufacturing sector, bronze coils are continuously processed into machine tool bushings and gear blanks, while white copper coils are used for continuous welding and forming of ship piping. Furthermore, in the new energy sector, cold-rolled pure copper coils are used to make conductive strips for photovoltaic inverters, and in the musical instrument industry, brass coils are continuously rolled into trumpet and saxophone body blanks (with stable acoustic performance). ​

Four key points to consider when using this material: First, material selection: For high electrical/thermal conductivity, choose cold-rolled pure copper coil (T2); for general performance, choose brass coil (H62); for wear resistance, choose bronze coil (QSn6.5-0.1); for seawater resistance, choose white copper coil (B10). Coil weight and thickness must match the production line (e.g., 5-8 ton lightweight coils for small stamping machines, 15-30 ton heavy coils for large rolling mills). Second, process protection: Control tension during unwinding (300-500N for cold-rolled copper coils, 500-800N for hot-rolled copper coils to prevent deformation or breakage). Use copper-specific dies for continuous stamping/cutting (to avoid surface scratches). Use copper-specific welding wire for welding (SCu-1 for pure copper coils, SCuZn-3 for brass coils). Clean up weld slag after welding to prevent impact on electrical/thermal conductivity. Third, storage should prevent oxidation: Store in a dry, sealed room at a controlled temperature. Temperature: 15-25°C, humidity <60%. Copper and brass coils can be coated with copper anti-rust oil or wrapped with moisture-proof film and kraft paper (to prevent oxidation and discoloration). They should not be stored with acidic substances (such as acetic acid and hydrochloric acid) or sulfides (such as rubber) to prevent corrosion and black spots. Regarding maintenance, unused copper coils should be tightly rewound (to prevent dust adhesion). Slightly oxidized surfaces can be wiped with cotton wool dipped in a copper-specific cleaner (containing citric acid and corrosion inhibitor). Severely oxidized coils (large areas of blackening or verdigris) should be scrapped to avoid affecting processing accuracy and performance. For decorative copper coils that need to maintain their color, they can be sprayed with a transparent copper protective agent after processing.