Most of the food and beverage cans are made of aluminum due to its unique properties for holding carbonated beverages and acidic food items. It is also favored for its weight to strength property where even less than half an ounce of beverage cans withstand more than 90 pounds of pressure per square inch. The fact that its shiny finish provides an attractive background for decorative printing is also necessary to grab the consumer’s attention.
The making of the beverage cans is through a process called a two-piece drawing which begins with an aluminum ingot around 30 inches thick rolled into a thin sheet. This sheet is cut into a circular blank which forms the bottom and sides of the can. The blanks are 14 cm in diameter. The wasted material from these blanks to make beverage cans are reused as scrap for the next batch.
The cups drawn through the initial process are transferred to another machine that punches the cup and redraws them to a diameter of around 6.6 cms. This redrawing increases the height of the beverage cans to 5.7 cms. The punch them pushes them against ironing rings that stretch the walls of the cans. This whole process happens as a single punch that takes less than one-fifth of a second to finish.
Another punch then presses the base of beverage cans to bulge inwards. This shape counteracts on the pressure created by the carbonated drinks. The bottom of the can is usually slightly thicker than the walls for improved strength. All of these processes leave the beverage cans with a slightly wavy top which are called ears.
The formation of ears is unavoidable due to the structure of the aluminum sheet. These ears are trimmed off that leave the upper walls straight and level which is required to set them with openings procured from an easy-open ends supplier. But that happens only after the beverage cans have been filled with the product.
The beverage cans now need just a simple polish and are sent for further finishing. The cans are cleaned, printed with the necessary labels and decorated as per the brand requirements. After this, the tops are squeezed slightly to provide an outward flange where the work of the easy-open ends supplier happens.
The lids are usually made of a different alloy of aluminum-containing more magnesium and less manganese than the rest of the body to be stronger to withstand the pressure of the liquid inside. Most easy-open ends suppliers have a variety of open ends in different alloy strengths depending upon the material they need to hold. These open ends are also available in various sizes as per the need of the customer. They are also much thicker than the walls and have a mechanism to open the beverage cans easily. They are made in a separate place and are fitted to the beverage cans once the items have been filled by bending the top against the lid and sealing it shut.