Why do food manufactures use cylindrical cans so often?



Why do they not use other shapes , such as a sphere or cuboid , why is it just restricted to cylinder?

In: Economics

Cylindrical cans can be opened with a can opener that runs along the edge. Spheres would be very difficult to open without making a mess, and cubes would require a pull tab. Some cans are rectangular and include a pull tab. Examples are spam and sardines.

Cylinders are strong and relatively simple to make.

A cylinder can be made with just 3 pieces, the side is just one piece of metal rolled into a tube, and then the top and bottom pieces get sealed on.

They also fair better than boxy containers because the corners of boxy containers concentrate stress and break, a corner less circle more evenly spread out load/impact.

The main draw back of a cylinder is all the little space that you lose between each cylinder, which is why no one uses spheres, they’re hard to pack and have a lot of empty space between them.

Cylinders are easier to pack, stackable and can be pushed up against each other pretty easily. Yes there is some wasted space that you wouldn’t get with cube containers, but the benefits of the cylinder (simplicity and strength) outweigh that negative.

Spheres hold the most volume within surface area, so it’s cheaper. Cylinders are also stronger for stacking, don’t have weak points at corners/seams, etc. Can be opened in a can opener.

Packaging stuff adds cost. The material costs something, and it’s added weight that makes shipping more expensive. It may not be much per can, but for millions of cans it adds up. So, you want to minimize the amount of material needed for packaging.

A sphere is the shape with the least surface area per volume. It’s also the strongest, since any stresses are evenly distributed across the entire surface. A sphere takes the least amount of material.

However, spheres are bad for packing and stacking. Whenever you stack spheres there’s a lot of space between them. That’s bad for shipping, obviously. You want to maximize the packing space so you can fit the most units per shipping container.

A cube (or cuboid) maximizes the packing because there is no space at all between them. But cubes take a lot of material. Those corners become points where stress gathers, which means you need even more extra material to keep them strong.

So, you need a compromise. A shape that’s almost as strong as a sphere and uses as little material as possible, but also packs and stacks almost as well as cubes. It also needs to be easy to make. Which shape is both sort of round and sort of square? Cylinders.

Edit: [Engineer Guy](https://youtu.be/hUhisi2FBuw) for an explanation from a real engineer, and also additional information about how cans are designed.

Durability, ease of manufacture, functional use.

Every corner or line requires a seam, which is a potential point of failure if the container is dropped, struck, or otherwise put under pressure. So a shape like a cuboid would have four more points of failure than a cylinder.

Spherical containers are much more difficult to manufacture than cylinders. They also don’t stack or otherwise store in stable arrangements on shelves without special shelving. *Opening* a spherical container is also fairly non-intuitive; additional modifications would be required to make the means of opening obvious and easy.

A cylinder hits the sweet spot: it’s very easy to consistently manufacture. It has only two points of failure: the top & bottom. It stores, stacks, and can be packaged easily without special adjustments. Opening it is fairly intuitive, as there is a clear “top” or “bottom”.

In any kind of container, the weak points are the edges. A cylinder does not have any edges on the side, so it is a stronger shape.

Now a sphere would be stronger, but it has some practical problems, such as stacking it. A cylinder is the best of both worlds.

I would imagine it’s the most cost effective way to package, ship, and store a product. With how long food has been packaged the way it is, I would hope someone would’ve found a better way by now if it’s significantly cheaper to do so.
The cylinder is probably the easiest shape a machine to make a can out of, it just has to curve a piece of metal and doesn’t have to worry about sharp bends that are too critical to have fail.