Aluminum Coil: Lightweight, Corrosion-Resistant, General-Purpose Metal Coil

Aluminum coil is a continuous coil made from pure aluminum or aluminum alloys through cold rolling, hot rolling, or annealing. Its core advantages are light weight, ease of processing, and corrosion resistance. Its cost is significantly lower than copper coil, making it one of the most widely used metal coils in sectors such as construction, packaging, and transportation, balancing practicality and affordability.
I. Core Categories
1. By Production Process
Cold-rolled aluminum coil: Rolled at room temperature, it features a thin thickness (0.1-6mm), a smooth surface (can be mirrored or brushed), and high dimensional accuracy. It is suitable for precision parts (such as electronic heat sinks and packaging foil) and resists deformation after processing.
Hot-rolled aluminum coil: Rolled at high temperature, it features a thick thickness (6-20mm), excellent toughness, and ease of welding. It may have an oxide layer on the surface and is primarily used for thick-walled structural parts (such as container sheet metal and large equipment casings). 2. Classification by Material
Pure aluminum coil (1 series, such as 1060): Contains ≥99% aluminum, exhibits excellent plasticity and bendability, but exhibits low strength. Suitable for packaging (food foil), decorative panels, and low-voltage electrical appliance casings, with an emphasis on ease of processing.
Aluminum alloy coil: Elements such as magnesium, silicon, and manganese are added to enhance performance. Common types include:
3 series (aluminum-manganese alloy): Highly corrosion-resistant, used for air conditioner outer casings and pipe insulation, offering excellent weather resistance;
5 series (aluminum-magnesium alloy): High strength and lightweight, used for ship panels and automobile bodies, balancing load-bearing and weight reduction;
6 series (aluminum-silicon-magnesium alloy): Can be heat-treated and strengthened, used for industrial frames and mechanical parts, and suitable for high-precision machining.
II. Core Performance: Advantages and Limitations
1. Advantages
Extreme Lightweight: With a density of only 2.7g/cm³ (approximately 1/3 that of steel and 1/3.3 that of copper), it offers significant weight reduction, making it a core material for lightweighting in transportation (automobiles, aviation) and construction. Naturally corrosion-resistant: A dense oxide film (Al₂O₃) forms on the surface, insulating it from air and moisture. At room temperature, it requires no anti-rust treatment and has a lifespan of 10-30 years (e.g., aluminum coils for building exteriors).
Easy to process and low-cost: It can be cold-rolled to ultra-thin thicknesses (e.g., 0.006mm aluminum foil) and can also be stamped, welded, and bent. Raw material and processing costs are only 1/5-1/8 of those for copper coils, making it suitable for large-scale applications.
Good thermal conductivity: Its thermal conductivity is approximately three times that of steel, making it suitable for heat sinks (e.g., LED heat sinks and appliance heat sinks). It is also non-magnetic and rust-resistant, making it suitable for a variety of applications.
2. Limitations
Low strength: Pure aluminum has a hardness of only 1/5 that of steel and suffers from weak impact resistance. It requires alloying (e.g., 5-series and 6-series aluminum) or subsequent processing (e.g., bending reinforcement) to increase its strength, making it unsuitable for use in heavy-duty structures. High Temperature Resistance: Aluminum's melting point is only 660°C, and its strength decreases significantly above 200°C. It cannot be used in high-temperature environments (such as boilers and engine components) and is limited to room or medium-low temperature environments.
Scratch and Deformation: The low surface hardness makes it easily scratched by sharp objects during transportation or processing. Thin aluminum coils (such as aluminum foil) are prone to wrinkling under stress, so proper protection is required.
III. Main Applications
Construction Industry: Aluminum coils are coated (such as fluorocarbon paint) to create "aluminum veneer" for office building exterior walls and curtain walls. Thin aluminum coils are used for roofing waterproofing and pipe insulation, relying on their weather resistance and lightweight properties.
Packaging Industry: Ultra-thin cold-rolled aluminum coils (aluminum foil) are used for food packaging (such as potato chip bags and aluminum foil lunch boxes) and pharmaceutical packaging (capsule aluminum-plastic composite panels), providing moisture and oxygen insulation and are recyclable.
Transportation: 5-series aluminum alloy coils are used in automobile bodies and wheels (reducing weight and saving fuel); 3-series aluminum coils are used in container side panels and ship decks, balancing corrosion resistance and strength. Electronics and Home Appliances: Pure aluminum coils are processed into LED heat sinks and computer case heat sinks (high thermal conductivity); aluminum alloy coils are made into washing machine drums and air conditioner casings, offering durability and lightweight performance.
Industrial Manufacturing: 6-series aluminum alloy coils are used for mechanical frames and automation equipment parts; hot-rolled aluminum coils are used for large storage tanks and equipment bases, suitable for welding and load-bearing applications.
IV. Selection and Maintenance Key Points
1. Selection Recommendations
Select pure aluminum coils (1-series) for packaging and decoration, 3-series for outdoor and corrosion-resistant applications, 5-series for transportation and load-bearing applications, and 6-series for precision industrial parts.
Cold-rolled aluminum coils are used for thin parts and high-precision applications, while hot-rolled aluminum coils are used for thick-walled parts requiring welding. Cold-rolled aluminum coils are preferred for applications requiring a high appearance (such as a mirror finish).
2. Maintenance Recommendations
Avoid heavy pressure and impact from sharp objects during storage. Thin aluminum coils should be tightly rolled and wrapped in plastic film to prevent deformation and scratches. Wipe surface stains with clean water or a neutral detergent, avoiding strong acids or alkalis (which can damage the oxide film and cause corrosion).
Minor scratches can be repaired by sanding and then reapplying a special aluminum paint. Severe deformation requires replacement to avoid compromising structural stability.
V. Future Development Trends
High-Strength Alloys: Develop higher-strength aluminum alloy coils (such as aluminum-lithium alloys) to further reduce weight and adapt to high-end applications in new energy vehicles and aerospace.
Green Production: Promote recycled aluminum coils (aluminum is 100% recyclable and consumes only 5% of the energy of virgin aluminum) to reduce carbon emissions and comply with the "dual carbon" policy.
Functional Upgrades: Develop "coated aluminum coils" (such as antibacterial and self-cleaning coatings) to expand applications in specialized applications such as medical and food processing; promote thinner profiles to meet the needs of flexible electronics and ultra-thin packaging.

In summary, aluminum coils, with their core advantages of light weight, low cost, and corrosion resistance, have become one of the most versatile metal coils. With advances in alloy technology and green processes, their application in high-end manufacturing and environmental protection will further expand.