Aluminum is made from a plentiful material found in the earth's crust. It occurs naturally in a mineral called bauxite. Most bauxite is mined overseas and shipped to the United States for processing. The aluminum in bauxite is formed when the material is refined to remove impurities. The refining process produces a fine, white powder called alumina or aluminum oxide. Electricity "zaps" the aluminum powder with a continuous electric current, which separates the aluminum from the oxygen. The electricity melts the aluminum so that it is hot and bubbly, like lava. Next, small amounts of other metals are added to the molten aluminum to add strength and corrosion resistance to the final product. The molten metal is cast into ingots or blocks, which are then rolled into long sheets and coiled (or rolled up like a sleeping bag). The aluminum is then sent to the can or end manufacturing plant.
The aluminum beverage can is made with two pieces — the can body and the can end (or lid). The manufacturing process starts with coils of aluminum. Can plants use mass quantities of aluminum coil every day to make can bodies or ends. Each coil typically weighs about 25,000 pounds and, when rolled out flat, can be anywhere from 20,000 feet to 30,000 feet long and five to six feet wide.
The aluminum coils arrive at the can plant and are loaded one at a time onto an "uncoiler" — a machine that unrolls the strip of aluminum at the beginning of the can making line and feeds it to the line, where it is first lubricated. Lubrication helps the aluminum flow smoothly during the can shaping processes that follow.\
A large machine called a cupping press starts the can shaping process. The press cuts circular discs from the aluminum sheet and forms them into shallow cups. The cups drop from the press onto the cup conveyor. These two metal-forming operations are performed at high speeds and make 2,500 to 3,750 cups per minute. The scrap (or skeleton) aluminum left over from these operations is removed and recycled.
From the cupping press, the cups are drawn up into higher cups through a series of iron rings. Now the aluminum is starting to look like a can.
The tops are trimmed off to make them even — each can is the same height and width.
A washer cleans and dries the can bodies so they can be decorated.
The cans proceed to a printer, where six to eight colors of ink may be placed on a can at the same time. The can spins around as the label is applied. Finally, a coating is applied that makes the outside of the can shiny and protects the newly applied paint.
Next, the can goes to an oven, where the paint and coating are baked onto the can to prevent chipping.
Next, the can's inside is coated with a spray to keep what is in the can from touching or reacting with the metal.
The can is baked in an oven again to seal the coating onto the can.