That was an interesting video, and the process is a bit similar to the cold impact extrusion that is used to form aluminum fire extinguishers, aerosol cans, and pop and beer cans. That process, however, forms a can in one punch from an extrusion press that runs up to a couple hundred strokes per minute. An aluminum slug about the size of a silver dollar is punched into a can 9 or 10 inches long in a mere blink of your eye. Bottom forming is very similar, but forming the shoulder or neck is done in a series of dies after the label is printed on the can. The printing on the shoulder area is actually misshapen at first and becomes normal after it is roll formed. It's fascinating to see the first time. After you see it happen 20 million times in a month, the fascination quickly wears off.
The Italians and Germans were using a process similar to this gas cylinder forming process in the late 1800's to pierce a short red hot billet to produce seamless steel pipe and tubing. Those pierced shells were further reduced in diameter, and much elongated, by running them through a rolling mill with a graphite coated mandrel bar which set the inside diameter. Much of this development was driven by the demands of the Arms Industry for producing cannon and rifle barrels.
