He’s back, [Bill Hammack] aka The Engineer Guy. He has a habit of revealing how the ordinary is extraordinary with a meticulous unveiling of all the engineering that goes into a thing. This time around it’s the aluminum beverage can. You might know it as a soda can, a beer can, or a salt-free air can. But we challenge you find someone who isn’t intimately familiar with these containers.
We know what you’re thinking: you already saw how these come into being on an episode of How It’s Made. You’re wrong. We saw that episode too. But just give [Bill] a few minutes of your time and he’ll suck you in for the rest of the episode. Now the die-forming of the base and side-wall, we’ll give it to you that you know what that’s all about. But then [Bill] busts into the history of these containers, citing the aluminum savings through reducing the top diameter of the can. He rounds it out with a celebration of the ingenuity of the modern “stay-on” tab which should make your glasses fall off with excitement.
If this is your first time hearing of The Engineer Guy you have a delightful weekend ahead of you. Binge watch his entire back cataolog! Our favorites include an analysis of a mechanical Fourier computer and the concepts involved in color anodization. We even read his book.
I love that he revisited this. The aluminum can had been touched on, but not in this much detail a few years ago when the channel was new. Way better than anything I’ve ever seen on TV.
And the award for most soothing voice goes to Bill Hammack!
Just for this video I enjoyed my last can of Baja Blast Mountain Dew I stocked up last summer.
And today one of my local Walmart had pallet full of Baja Blast Mountain Dew out so I picked up 6 cases. On sale $3 per case too! As an added bonus, there’s Sangria Mountain Dew as well!
The featured image is a bit scary looking.
It took a few seconds for my brain to process what it was. At first I thought it was a close-up image of a finger with it’s guts spilling out.
Wow, I never knew there was so much to a simple aluminum can, now I feel guilty about crushing the empties on my head! One thing that struck me was the pressurization keeping the can strong, wasn’t a similar approach taken with the fuel tanks in Atlas rockets? And one more thing, the opener for the no tab cans was called a “church key”.
I forgot to add my favorite part to the article: aluminum is the most recyclable substance known to man. It takes less energy to recycle it than to smelt it from bauxite in the first place.
I would think that applies to any metal. When you consider mining the iron ore and then turning it into usable metal, getting that metal ready uses less energy. That’s why i throw my metal to the metal recycling bins, even the smallest things. Though it kinda sucks that they have those airplane cemeteries and they sink huge ships and the metal is lost. You could recover lots and lots of stuff from there.
The airplanes in the airplane “cemetaries” get recycled eventually. Even the ships in Mauritania are being “slowly” recycled..
http://www.artificialowl.net/2008/12/probably-one-of-largest-boat-graveyard.html
Yeah I mean isn’t salvage often cheaper than mining raw materials?
And the fact that even though it’s highly reactive in an oxygen atmosphere it is usable because it forms a microscopic layer of aluminium oxide, which is what rubies are made of, it has to be the only metal we use that is naturally coated in precious jewels!
I used to marvel as a kid at the Americans on TV crushed cans on their head … until I realized we didn’t have the same kind of cans. Best not try that over here in the Netherlands, the torn steel can have sharp edges.
I think starting at about 02:47 he makes an error: He says the domed bottom uses less material than if the bottom were flat. No… The dome is pressed out of the flat bottom. Therefore no new material is added so the dome has the same amount of material as the previously flat bottom. Although the dome is now thinner. What the dome does do for the can is strengthen the end as well as resist pressure pushing out and deforming the bottom when the can is full and sealed.
What he (probably) means is that a domed bottom uses less material than a flat bottom with equivalent strength.
Perhaps the idea is that in order to make at flat bottom that would withstand the pressure it would have to be made out of sufficiently thick material that it would use more material overall.
Initially that was also what i thought.
But when flat you have a given amount of pressure applied to a disc surface.This means the net force at every point due to pressure would be F=p/A (F:force vector,p:pressure,A:surface area). The total force will be the sum ΣF.Since all F point the same direction ΣF = F1+F2+..Fn.
With the concave bottom the same formula applies.But now every F has a slightly different direction.
This means that the sum of forces will be smaller as you will have forces cancel out other forces.
This force elimination allows us to use less material.
(I am not a physicist, but i think this is what happens)
You are correct that the name of the game is force redirection. With a concave dome added pressure will actually cause the can to grow until it buckles, whereas with a flat bottom the can will just bulge. Food cans made from the same DWI (draw, wall iron) process have a flat bottom because they have different requirements, namely surviving both pressure and vacuum during retort. That is the reason there are strengthening beads of food cans, so that they do not crush or panel during retorting.
As an R&D engineer for a major can company, I am of the firm belief that cans are the most highly engineered product that is designed to get recycled without any thought given to the tolerances or speed at which they are made.
My Pa used to be a QC Engineer at CCC back in the day. He used to bring home all kinds of prototype cans (many times filled with product) . I remember when pull tabs were being retired. We tried at least a couple of “innovative” pop tabs that summer that never made production. Wish I’d have known to save a couple.
Sorry, Correction & Clarification to my OP:
I was only addressing the presenter’s statement that (At 3:00), “…that dome reduces the amount of material used to manufacture the can…”.
No… The dome is pressed out of the flat bottom. Therefore no new material is added so the dome has the same amount of material as the previously flat bottom. Although the dome is now thinner.
That said…
To be fair: This is a short video, and obviously the presenter cannot go into the complex plus and minuses that come with the mechanical design of an ideal or near-ideal purely cylindrical pressure vessel vs. one that is cylindrical with a single spherical-end.
The problem is more complex when you introduce convex vs. concave end piece (obviously, you want a concave end piece in a soda can so it doesn’t tip-over). Keep in-mind, although the concave end in this soda can example is preferred to a flat or convex bottom end to prevent tip-over when placed on a flat surface, for an equivalent analysis of concave vs. convex for a given cylinder length, the total volume would have to be adjusted so they are the same (e.g. longer cylinder for the concave case.) The total dimensions for each case do affect total volume, which for comparison purposes you want to keep the same.
Also, keeping in-mind that the bottom was made (stamped) from a disk of bottom material, the resulting domed end will have less material thickness than the disk-shaped original it was made from. This will affect the withstanding pressure of the thinner domed-end vs. the thicker cylindrical end it was stamped from. I would need to wade through the equations (my Engineering Statics is rusty), but I feel that in near-ideal cases the in the mathematical comparison of the purely cylindrical vs. cylindrical plus one domed convex end-cap cases, with equal volume, will result in some pretty simple relationships. But I may be wrong.
Here are a couple of links if you want to delve deeper into this from the standpoint of how the different designs work as pressure vessels. Analyzing the trade-offs of the two cases from a mechanical point of view (e.g., crush withholding) when the soda can is open (not pressurized), is another exercise entirely.
http://en.wikipedia.org/wiki/Pressure_vessel
http://www.mathalino.com/reviewer/mechanics-and-strength-of-materials/thin-walled-pressure-vessels
Another advantage of the domed bottom is that it secretly reduces volume of the product.
Wow, i have a flashback. Around 1996 there we had to build a machine prototype that forms the traditional Coke can similar to the classic bottle. That was a beast of a machine. As far as i know, they came only to market for a test. Found this:
http://beachpackagingdesign.com/boxvox/rise-and-fall-of-the-contour-can. And of course there is no mention, that we build this here in Switzerland….
It’s funny to think that the coating on the inside prevents aluminium seeping intoo the product, aluminium which is harmful to the nerve system, but the material used for the coating has been shown to also be harmful.
Meanwhile I noticed a year ago or so that suddenly more and more cans that used to be aluminium were suddenly iron, I gees it’s the economic crisis combined with the shenanigans of the big banks who as it turns out store metals like aluminium (and copper) in large warehouses to artificially keep the price up when in reality there is an overproduction (check news sites for stories about the senate committee who investigated it).
Anyway it seems to slowly go back to aluminium again now, so maybe that’s a good sign.
If people stockpile aluminium when it’s cheap, and sell it when it’s expensive, they are only helping to keep the price at a more constant level, which benefits both producers and consumers.
The senate comission called it ‘immoral but not illegal’ if I recall correctly… and that’s the US senate mind you from the heart of capitalism.
So yeah, I think you are trying too hard to find excuses, and it really isn’t about buying low and selling high but about pushing the price up artificially at the detriment of the entire planet.
Pitty he didn’t explain how they are able to make the fine “scratch” at the lid at which it rips open. It never leaks and at the same time it always rips open like it should. This keeps puzzling me. How do they do that? One time, oke, I get that. A few times, no real problem, I guess. But thousands upon thousands of times?
Ro
The ends go through their own press operations that are at least as complicated as can making. For the “scratch“ aka score that you are referring to, is done in a single operation out of 8 steps at speeds of up to 750 strokes/minute while holding a tolerance of about .0004“ of an inch. It’s truly amazing.
We have local beer in the new wide mouth aluminum cans. Silkscreen graphics and all.
I am waiting for the PETA crowd to defend drunken squirrels or whatever critter will get stuck in them.