What is the reason for the grooves that go around the circumference of a tin/aluminium can? It can't be for grip because they're covered with paper anyway and i don't think it would make much difference.
If they didn't, they would easily be crushed during shipment. It makes them much stronger to have the grooves. Norrie's got a good point.
To allow for expansion and contraction when temperature varies. (Strength would be from Vertical grooves). (Thanks (Ω)Jack).
This is the correct answer. This is a Microsoft Interview Question Source: How Would You Move Mount Fuji?: Microsoft's Cult of the Puzzle -- How the World's Smartest Companies Select the Most Creative Thinkers There was a time when cans were in rectangular shape and made of heavy steel. As can companies became more cost and environment conscious, they figured out ways to switch to thinner aluminum cans. The thin aluminum is less strong. Like eggshells, today's cans are just about as thin as they can be and still reliably enclose their contents. This demands architectural tricks that weren't necessary with the steel cans. The thickest and strongest part of the can is the top, attached separately with a crimp. The top has to stand the stress of someone ripping open the flip top. Because the top is thicker metal, the manufacturers found it desirable to minimize its diameter. So they shrunk the top a little. This meant adding a bevel at the top to connect it to the rest of the can. (They couldn't shrink the diameter of the whole can, or it would hold less beer.) Once you shrink the top, you also have to shrink the bottom, for the cans are supposed to stack. Both top and bottom are tapered. There are other reasons why thebottom is tapered. The bottom and middle are pressed from a single piece of thin aluminum, eliminating the extra step of attaching a separate bottom to the can. This is easiest to do when there is a bevel rather than a sharp right angle. The bevel also makes the can a little more dent-proof at the ends. You could get a similar strengthening effect with a convex bottom, but then the cans wouldn't stack.
