The manufacturing of 500ml aluminium cans begins with aluminium coil processing. Raw material is usually 3104 aluminum alloy in its original thickness trimmed from 0.28mm to 0.11mm by the cold rolling process, and material usage ratio is 98.5%. Ball Corporation, the world’s largest manufacturer of aluminum cans, has, for example, a high-speed cup machine with a press capacity of 2,800 cup billets per minute, a single press pressure of 300 tons, and a mold life of more than 100 million times. After the cup is formed, the blank diameter is 56 mm and the height is 35 mm. After being subjected to 18 stretch-thinning processes, the tank height is raised to 122 mm, and wall thickness uniformity error is maintained within ±0.005 mm.
Four-stage countercurrent rinsing system is utilized in cleaning and surface treatment process, the temperature of water is 60-70 ° C, the concentration of acid and base is accurate to 0.5%-1.2%, the consumption of water for each thousand cans reduces from 50 to 8 liters in the standard process, and the energy-saving rate is 84%. The German KHS production line is also provided with plasma cleaning technology, and the surface can be raised to 72 mN/m, which increases the adhesion of the subsequent printing ink by 40%. The Keyens Vision inspection system checks the tank at 200 frames per second, with a 99.99% defect detection rate and compression of scrap from 0.3% to 0.02%.
The printing process uses an eight-color UV digital press with 1,200 dpi resolution, which can print 120,000 cans per hour with a very accurate ink thickness of 3-5 microns. Japan Toyo Tank’s low-temperature curing technology reduces the baking temperature from 180 ° C to 120 ° C, reduces energy consumption by 35%, and reduces VOCs emissions by 90%. The necking process reduces the diameter to 53 mm from 66 mm, makes the neck 0.16 mm thick, and enhances the compressive strength to 90 lb force (about 40.8 kg force), meeting the logistics requirements of the stacking height of 15 meters.
The inner coating technology utilizes water-based epoxy coating, the dry film thickness of 2-3 microns, and the dense barrier formed after curing with high temperature of 230℃. The BPA-Free coating made by the PPG company in America has improved its corrosion resistance by 50% and remains intact even after cooking at 120 ° C /30 minutes. Crown’s laser welders seal the bottom of tank 4,000 times per minute, weld strength as high as 28 MPa, and helium leakage rates lower than 1×10^-9 mbar·L/s.
Quality control system completes the whole process, roundness deviation of tank body is less than 0.05 mm, and volume tolerance is regulated in ±1.5ml. Oregin uses X-ray detector to scan the weld with a resolution of 0.1mm, and defect location accuracy is up to 0.01mm. The final inspection process ensures the tightness by negative pressure test (-60kPa for 30 seconds) and high-speed photography (100,000 frames/second), and automatic removal rate of defective products is 100%.
For the sake of saving costs and for the protection of the environment, recycled aluminum accounts for 73% of the production of 500ml aluminum cans, and by each ton of recycled aluminum, only 1,300 KWH of energy is used, 93% less than that which is used by original aluminum. The closed-loop recycling technology of Novelis increases the percentage of aluminum scrap recycling to 99%, saving the company $4.8 million every year per plant. China Baosteel aluminum can production line through intelligent temperature control system, the annealing furnace energy consumption reduced from 1.2 kWh/kg to 0.8 kWh/kg, the reduction of 12,000 tons of carbon dioxide emission per year.