Bill Hammack details the engineering choices underlying the design of a beverage can He explains why it is cylindrical, outlines the manufacturing steps needed to created the can, notes why the can narrows near it lid, show close ups of the double-seam that hold the lid on, and details the complex operation of the tab that opens the can.
The video is great but the reason i decided to save it on The Glass Files is to preserve this comment written by a YouTube user named Graves Clayton:
"My father was an engineer at Reynolds Can Division from 1980 to 1995. Can production efficiency was his primary work. Do you you know why the one-piece aluminum can needed a neck in the first place? If you think it was designed that way to begin with, you would be mistaken! In fact, much of what is apparent in the final product, and appears to be engineering perfection, is actually the result of a lot of trial and error.
Beverage companies fill and cap the cans, so when the first series of one-piece cans were made, they were shipped to the beverage companies with a load of standard diameter tops. The beverage companies very quickly discovered that the can would not roll straight after being filled and capped, because the cap was a larger diameter than the can, ooops! Can manufacturing had overlooked this because they did not fill and cap the cans. So the first necking machine was made along with new lids that were the same diameter as the can. This was dubbed the single-neck can, but when assembled, the can appears to have no neck.
After several production runs, it was eventually discovered that less aluminum was being used for "Lid Production" because a smaller lid was used for each reduction in can neck diameter. (PLEASE NOTE: Doming the bottom and Necking does NOT reduce the amount of aluminum in the can itself, as the can is formed from the same billet stock, regardless of either process).
Reynolds then began experimenting with the number of times this diameter could be reduced and still maintain the strength of the can neck. Their end result was the quad-neck (4) can (most commonly found on Miller Beer cans) and had 3 visible steps on the can neck. But each necking step required multiple stops, additional machinery space, and so on. This was slowing can production speed and increasing production expense, in opposition to the amount of aluminum saved in lid production.
The neck needed to be formed in one step without stopping the can movement, and without all the extra machinery. Other manufacturers were stamping the neck, but only once to reduce the lid diameter. Also, multiple necking steps were increasing the can height and resulted in non-uniform can heights depending on who bought what brand of can.
This non-standardization was creating packing and distribution issues for the beverage companies who bought cans from multiple manufacturers. So the question became how to create a standard height can with the small diameter lid achieved with the quad-neck can? This was done by starting the single neck at a lower point on the can, and forming it in a single non-stop process.
So, how is the current no-step neck formed? It is not stamped or formed in the conventional sense. It is actually formed by spinning the can and pulling the neck up and into a smaller diameter while the can is in motion on the production line. This is done in one step (not multiple steps in 7/10ths of a second). This process was invented by my father and a machinist at Reynolds experimenting with can formation and deformation in the Can Division machine shop. Their idea came from the way in which clay pottery is spun and pinched into thin vases with long necks. Reynolds patented this process and called it their "spin-flow" can. This process eliminated tons of additional machinery and immediately increased production speed to better than the single neck can as well.
In addition, Reynolds went on to construct their own can production machinery rather than buying from other builders, and became the top seller of aluminum can production lines which they would sell to beverage companies world wide.
The Spin-Flow necking process was picked up by other manufacturers only after Reynolds Can Division closed and sold their entire can production operations to Alcoa."
published on April 14th, 2015
video: Bill Hammack / personal history: Graves Clayton