Beverage Can Ends and its Opening Devices

Unipack.Ru offers our reader the article “Beverage Can Ends and its Opening Devices” written by Anton Steeman, renowned expert on packaging, from his blog Best In Packaging.

Although the position of beverage cans have been threatened by HDPE (high-density polyethylene) and PET (polyethylene terephthalate) bottles, advancements in packaging technology have seen the introduction of improved functional features, a major factor for growth in the beverage end-use sector.

Two holes made with a church key

The early metal beverage can was made out of steel and had no pull-tab. The can was opened by punching two triangular holes in the lid – a large one for drinking, and a small one to admit air. For punching the holes often a so called church-key was used. As early as 1936, inventors were applying for patents on self-opening can designs, but the technology of the time made these inventions impractical. Later advancements saw the ends of the can made out of aluminium instead of steel.
Pull-tab

In 1956 Mikola Kondakow of Thunder Bay, Ontario, Canada, invented the pull tab version for bottles (Canadian patent 476789). Then, in 1962, Ermal Cleon Fraze of Dayton, Ohio, invented a similar integral rivet and pull-tab version for cans (also known in British English as ring pull), which had a ring attached at the rivet for pulling, and which would come off completely to be discarded. He received U.S. Patent No. 3,349,949 for his pull-tab can design in 1963 and licensed his invention to Alcoa and Pittsburgh Brewing Company. The latter introduced the design on its Iron City Beer cans.
The pull-tab got a lot of critics as it littered the roadside and caused injuries due to the very sharp edges of discarded tabs on beaches and in parks.

Stay-on-tab

The pull-tabs were eventually replaced almost exclusively by the stay-on-tabs we still use today. Stay-on-tabs (also called colon tabs) were invented by Daniel F. Cudzik of Reynolds Metals in Richmond, Virginia, in 1975.

The mechanism uses a separate tab attached to the upper surface as a lever to depress a scored part of the lid, which folds underneath the top of the can and out of the way of the resulting opening. This design reduced injuries and reduced roadside litter caused by the removable tabs.

Beverages began using this new type of tab in the United States by 1977. Such “retained ring-pull” cans supplanted pull-off tabs in the United Kingdom in 1989 for soft drinks.

Top end or lid

To support the mechanism of the tabs, the lid is made of a slightly different alloy than the aluminium for the base and sides of the can. The inward bulge of the bottom of the can helps it withstand the pressure exerted by the liquid inside it, but the flat lid must be stiffer and stronger than the base, so it is made of an aluminium with more magnesium and less manganese than the rest of the can. This results in stronger metal, and the lid is considerably thicker than the walls.

The centre of the lid is stretched upward slightly and drawn to form a rivet. The tab, a separate piece of metal, is inserted under the rivet and secured by it. Then the lid is scored so that when the tab is pulled by the consumer, the metal will detach easily and leave the proper opening.

And that’s roughly the situation we still have. Over the years since the introduction of the stay-on-tab only minor modifications have been seen. Let’s have a look at the most recent and significant ones.

In a busy, saturated market, it is sometimes the seemingly simplest changes to a package that can make a difference. From the moment consumers started to drink straight from the can, there have been two complaints.

The first of course is the restricted flow of liquid and the “glugging”, the second is the effect of stilling of the beverage after a can is opened and not emptied at once.

Over the last years we have seen some innovations to answer these consumer complaints.

Read the whole article in the blog Best In Packaging