11–20 of 92 posts
so when trucks would drive their chips out to California, some of the seals would open up due to the pressure difference between the high altitude air and the air sealed inside the bag This is backwards, isn't it? Less dense air from Colorado would shrink the bag in California.
Yeah, it is. Your shampoo usually opens on the pass. At a guess, maybe he meant the plants were east of the mountains, not west, so they would have to drive over them?
Seems like a good design would be to have seals that are extra-weak to shear forces while being strong for all the other kinds.
so when trucks would drive their chips out to California, some of the seals would open up due to the pressure difference between the high altitude air and the air sealed inside the bag This is backwards, isn't it? Less dense air from Colorado would shrink the bag in California.
Seems like a good design would be to have seals that are extra-weak to shear forces while being strong for all the other kinds.
One type of seal I see has a nick in the side. It's still sealed, but the nick gives you something to leverage, so you can tear the packet open. Perhaps this isn't as common in the US?
God, all this talk of cereal and jerky and ramen makes it sound like I eat only crap. I eat vegetables, I swear!
Seems like a good design would be to have seals that are extra-weak to shear forces while being strong for all the other kinds.
One type of seal I see has a nick in the side. It's still sealed, but the nick gives you something to leverage, so you can tear the packet open. Perhaps this isn't as common in the US?
Stress risers are a common cause of structural failure, and are usually designed around. Some well known examples where they cause failures: rectangular window openings in aluminum fuselages, knots in fishing line, a poorly designed head tube lug on a steel bicycle frame.
In this case, however, the failure of the material results in a good outcome: snack time.
Seems like a good design would be to have seals that are extra-weak to shear forces while being strong for all the other kinds.
Given the shape of a bag, it seems pretty difficult to put shear force on the bag. Since the sealed layer deforms and crumples, if for example you grabbed onto both sides of the middle of the top edge and tried shearing them apart, they would just reorient so that the forces are now more or less normal to the glue...
so when trucks would drive their chips out to California, some of the seals would open up due to the pressure difference between the high altitude air and the air sealed inside the bag This is backwards, isn't it? Less dense air from Colorado would shrink the bag in California.
I think the most interesting part of this post was the comment about how they use multiple scales with chips to get closest to the desired value. This is really a neat hack that probably allows for much less precise chip dumpers. I'm reminded of how awesome randomized algorithms in CS can seem, but in real life it is just extra magical.
More a case of discrete chip mass. You could have very accurate chip scales, load cells are cheap and very accurate - but how do you select exact 'N' grams of random sized potato chips? Having a set of pans, where the first has eg. 17chips with a mass of 4.5g, the next has 19chips with a mass of 5.9g etc and then selecting from 4 of them them to hit the 20g bag size is very clever.
Simplifying the scenario might clarify what's happening. Imagine any given chip could weigh 1-2oz. And you are trying to fill a 2oz (minimum guaranteed content) bag. You already have 1 chip in the bag, weighing 1oz. The next chip you add (think "marginal" from econ class) weighs anywhere from 1-2oz and could tip the scale all the way up to 3oz, when you are only looking for 2oz in the bag. But if you use two scales, you have now a choice of TWO chips to put in the bag, so you pick the one that weighs closest to 1oz. And ultimately this allows you to fill more 2oz bags with the same quantity of chips.
At 4:10 in this video https://www.youtube.com/watch?v=LkqBbr7Ewsw you can see a VFFS machine in action. (I find 'how its made' to be musak for nerds but that is a different post :-)