Beverage can

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The ring pull opening mechanism characteristic of post-1970s drinking cans.

A typical can of Diet Coke.

Many companies use inflatables that look like an aluminum can, such as this one by Sierra Mist.

A beverage can is most often an aluminum can manufactured to hold a single serving of a beverage, usually a carbonated one.

1 Overview
2 Current characteristics
3 Fabrication process
4 Older can designs
5 See also
6 References
7 External links

[edit] Overview

The earliest kind of metal beverage can was made out of steel (similar to a tin can) and had no pull tab. Instead, it was opened by using a tool called a can opener or bottle opener (colloquially, a church key). The opener resembled a bottle opener but had a sharp point. The can was opened by punching two holes in the lid, a large one for drinking through, and a small one that allowed air in to replace the displaced fluid. Further advancements saw the end pieces of the can made out of aluminum instead of steel.

The first kind of all aluminum can was the same as its forebears, which all still used the church key to open them. In 1959 Ermal Cleon Fraze (from Dayton, Ohio) invented the familiar integral rivet and pull-tab version, which had a ring attached at the rivet for pulling, and which would come off completely to be tossed aside. He received U.S. patent No. 3,349,949 for his pull-top can design in 1963 and sold his invention to Alcoa and Pittsburgh Brewing Company. It was first introduced on Iron City beer cans by the Pittsburgh Brewing Company. 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.

The original pull tabs were actually pop tops where the tabs came off in the user's hand, which allowed people to make curtains out of them by hooking the popped off tabs to one another to make a chain. Enough chains side-by-side made a curtain.

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"). Also, some people dropped the tab into the can after opening it, rather than finding a wastebasket in which to throw the tab away. They then drank the beverage directly from the can, occasionally swallowing the sharp-edged aluminum tab by accident.

Stay tabs (also called colon tabs) were introduced by the Falls City Brewing Company of Louisville, Kentucky in 1975, partly to prevent the injuries caused by removable tabs. Stay tabs almost completely replaced pull tabs by the early 1980s. In this can model, 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).

Several alternatives to the pull tab have been trialed with little commercial success. One notable variation was the press button can which effectively featured two pre-cut holes (one large, one small) in the top of the can, with these holes sealed with a simple plastic membrane. By design, these buttons were also held firmly closed by the outward pressure of the carbonated beverage contained within.

To open the can, the consumer would press both buttons into the body of the can, thus opening one through which to drink the beverage, the other to provide sufficient air to allow the contents to flow more easily. The buttons would remain attached to the can, alleviating the earlier issues with pull tab ingestion.

A major disadvantage of this closure method was that a consumer could open a press button can and either remove, replace or taint its contents, before agitating (shaking) the can with sufficiently enough to force the press buttons to re-seal the can, with little evidence of the can ever being tampered with. Another disadvantage was that in the process of pressing the buttons (particularly the larger drinking button) it was too easy for the consumer to either cut themselves on the sharp edge of either hole or get a finger stuck inside the can whilst attempting to open it.

One prominent design feature of beverage cans is that they almost invariably have a slightly tapered top and bottom. Under examination, it is seen that the metal on the lid of the can is significantly thicker than the metal on the sides. This means that a great deal of raw materials can be saved by decreasing the diameter of the lid, without significantly decreasing the structural integrity or capacity of the can. In fact, the amount of taper on the average aluminum beverage results in a savings of about 15% versus a non-tapered can. This structural integrity becomes apparent in the construction of beeramids - pyramid-shaped stacks of empty cans popular in some college dormitories.

The most modern advance in can design has been the 'wide mouth' can -- the opening for the liquid to come out was enlarged in the late 1990s.

[edit] Current characteristics

A can of San Pellegrino Aranciata, with a separate foil lid.

In North America, the standard can size is 12 fluid ounces (355 ml). In India and most of Europe, standard cans are 330 ml, which is approximately 1/3 of a liter. In Australia, the standard can size is 375 ml. In South Africa standard cans are 340 ml.

A single empty 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 or 24 pack cases.

Typical uses of aluminum cans:

In Russian local markets, strong alcohols such as Vodka are available in aluminum cans.
In Japan, canned fresh air is available. This is most popular in the Tokyo area.
In Denmark, aluminum cans were banned between 1982 and 2002.

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 most cost effective materials to recycle. 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. 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. In addition, some people believe that aluminum leaching into the fluid contained inside can be dangerous to the drinker's health.[1] The exact role (if any) of aluminum in Alzheimer's disease is still being researched and debated ^[1]^[2]. Aluminum cans contain an internal coating to protect the aluminum from the contents. If the internal coating fails, the contents will create a hole and the can will leak in a matter of days. There is some difference in taste, especially noticeable in beer, presumably only 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.

[edit] Fabrication process

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.

Plain lids are stamped out from a coil of aluminum and are transferred to another press that converts them to easy-open ends. The conversion press forms an integral rivet button in the lid and scores the opening, while concurrently forming the tabs in another die from a separate strip of aluminum. The tab is pushed over the button which is then flattened to form the rivet that attaches the tab to the lid.

Finally, the top rim of the can is trimmed and pressed inward or "necked" to form a taper conical where the can will later be filled and the lid (usually made of an aluminum alloy with magnesium) attached.

[edit] Older can designs

There were also cans in the USA called conetops and crowntainers that were shaped like an old American-style brake fluid can from the 1970s. There were three types of conetops: high profile, low profile, and j-spout. The low profile and j-spout were the earliest, dating from about 1935, the same as the flat top cans that had to be opened with an opener. The crowntainer was a different breed of can that was drawn steel with a bottom cap and the favorite of some collectors. Crowntainers and conetops were made by various breweries until the late 1950s but not every brewery made every variety mentioned above. Crowntainers were developed by Crown Cork & Seal, now known as Crown Holdings, Inc., a leading beverage packaging and beverage can producer.