Aluminum can

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Image:Diet Coke.jpg Image:Sanpellagrinoaranciatacan.jpg The aluminum can or aluminium can is a popular beverage can made of aluminum, first introduced by the Coors Brewing Company. Previous cans had been made of steel.

Modern cans are generally produced through a mechanical process that involves punching a flat blank from very stiff cold-rolled sheet. This sheet is typically alloy 3104-H19, which is aluminum with about 1% manganese and 1% magnesium to give it strength and formability. The flat blank is first formed into a cup about three inches in diameter. This cup is then pushed through a different forming process called "ironing" which forms the can. The bottom of the can is also shaped at this time. The malleable metal deforms into the shape of an open-top can. With the sophisticated technology of the dies and the forming machines, the side of the can is significantly thinner than either the top and bottom areas, where stiffness is required. One can-making machine can turn out about 500 cans per minute.

Finally, the top rim of the can is trimmed and pressed inward to form a taper conical where the can lid will later be attached.

The lid contains a scored region and a pull tab that can be leveraged to open the hole (by pushing the scored region into the can). The lid for the can is usually an aluminum alloy with magnesium. The lids are stamped out from a flat sheet and formed in a single operation. The pull tab is made a similar alloy, and the tiny rivet connecting the two is a different, softer alloy. These are assembled before the lid is attached to the can.

Before 1974, beverage cans were opened by pulling a tab that completely removed a portion of the can's lid. These pull tabs were a common form of litter—and a lingering hazard for bare feet, especially at public beaches (as witnessed in the third verse of the Jimmy Buffett song "Margaritaville"). A further danger occurred when users dropped the tab into the can after opening it, and then drank from it; occasionally the sharp metal tab would be ingested or inhaled.

Although the idea of a stay-on tab seems simple, it took Dan Cudzik, a tool engineer from Reynolds Metals, five years to perfect it. Others had given up on trying to make a stay-on tab purely out of a metal, convinced that plastic had to be added. The stay-on tab has had a huge impact on the environment, keeping trillions of aluminum tabs off the ground since it was introduced.

Because they are made of aluminum, these containers are very suitable for recycling. When recycled without other metals being mixed in, the can/lid combination is perfect for producing new stock for the main part of the can - the loss of magnesium during melting is made up for by the high magnesium content of the lid.

In many parts of the world a deposit can be recovered by turning in empty plastic, glass, and aluminum containers. Unlike glass and plastic, aluminum cans are often purchased in bulk by scrap metal dealers, even when deposits are not offered. Aluminum is one of the few substrates that is cost effective to recycle. Their metal construction also conducts heat more readily than glass or plastic, and drinks in aluminum cans can be chilled more quickly than those in other containers.

Many consumers find the taste of a beverage from a can to be different from fountain drinks and beverages from plastic or glass bottles. Additionally, some people believe (incorrectly) that aluminum leaching into the fluid contained inside can be dangerous to the drinker's health. The fact is, the internal coating is there to protect the aluminum from the contents and if the internal coating fails, the contents will create a hole and the can will leak with in a matter of days. There is some difference in taste, especially noticeable in beer, due to traces of the processing oils used in making the can. Oils used in can manufacturing are FDA approved and must be constantly monitored.

The first soft drinks to be sold in all-aluminum cans were R.C. Cola and Diet-Rite Cola (both made by the Royal Crown Cola company), in 1964.

A single empty 12 fluid ounce aluminum can weighs approximately 15 grams, or 0.5 ounce. Therefore there are roughly 30 empty aluminum cans to an avoirdupois pound.

One problem with the current design is that the top edge of the can may collect dust or dirt in transit, if the can is not packaged in a completely sealed box. As illustrated here, some beverage makers have experimented with putting a separate foil lid on can tops as one solution. To help solve this problem, many marketers are shipping cans in cardboard 12 pack or 24 pack cases.

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