The guy who made it so difficult to open your bag of potato chips

http://www.rheothing.com/2012/05/im-that-guy.html

by jmjerlecki • 14 years ago

160 91 14 years ago

TamDenholm• 14 years ago

I love learning about things I would never come across in everyday life, like how a packing machine works and the problems no one would ever think to think of like air pressure and altitudes. Then also the restrictions put in place and how to come up with a creative solution to a problem. This is the kind of stuff I live for.

nickpinkston• 14 years ago

Check out this playlist of manufacturing processes - pretty cool: http://www.youtube.com/playlist?list=PL3AFB507B668AF162

minikomi• 14 years ago

I think my love of these kinds of videos started with this: http://www.youtube.com/watch?v=HMU-wXsgyR8

ahelwer• 14 years ago

The air pressure certainly has an effect. I live in an only somewhat-high-altitude city (Calgary) and most of the chip bags you see are puffed up like balloons.

graywh• 14 years ago

Once had a bag of chips burst while driving up into the Rockies.

mcpherrinm• 14 years ago

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.

excuse-me• 14 years ago

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.

hammock2• 14 years ago

Exactly. It allows for less-precise (i.e. more variability) chip size, not chip scales. :)

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.

arocks• 14 years ago

True. Straightforward application of the Knapsack problem: http://en.wikipedia.org/wiki/Knapsack_problem

leot3• 14 years ago

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.

scott_w• 14 years ago

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?

leot3• 14 years ago

It is, though it doesn't always work, and it's easy to tear a sub-optimal opening.

jff• 14 years ago

I see them over here all the time... you'll find them on jerky packets, for example, or as the initial seal on nearly any re-sealable bag (think of a bag of cereal with a zipper on top). The problem is that if the Seal God (blessed be his flippers) doesn't smile on you, you'll end up ripping off a sliver of the top of the bag and completely failing to get a decent opening. This has caused much wailing and gnashing of teeth. I think the material used for the bag/packaging is definitely a factor--I can pretty much always make a good tear on a ramen flavor packet, but I don't know that I've ever had a bag of jerky open properly.

God, all this talk of cereal and jerky and ramen makes it sound like I eat only crap. I eat vegetables, I swear!

reneherse2• 14 years ago

The nick you're describing creates what structural engineers call a 'stress riser' in the material of the bag. It focuses the force you exert on the bag to a small point, from which the tear will originate.

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.

FuzzyDunlop• 14 years ago

They frustratingly don't often work with greasy fingers. Which you might have if said sachet or packet comes with, say, a fast food meal, or from inside a bag of crisps (like Salt n Shake in the UK).

icegreentea• 14 years ago

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...

leot3• 14 years ago

Apply thumb and forefinger on either side of the seal. Press together and slide. Coefficient of friction between finger and seal might need to be increased somehow (perhaps by texturing the material differently at that point).

ChuckMcM• 14 years ago

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 :-)

calloc2• 14 years ago

I've been watching "How It's Made" on NetFlix, I am on Season 3 and it is awesome. Although, I do tend to get hungry for the foods they show :P

philwelch• 14 years ago

Really? That show always turns me off of eating processed foods. If I watched it every day I'd go paleo for sure.

sciurus2• 14 years ago

You can link directly to 4:10 in the video.

https://www.youtube.com/watch?v=LkqBbr7Ewsw&t=4m10s

bmelton3• 14 years ago

Holy shit that's brilliant.

I admittedly haven't been to Youtube in forever, but that actually got me to click, if only to find out how (other than altering the querystring by hand) you did it.

I still didn't see how to do it though. Is that a logged-in option perhaps or am I just missing something?

carguy19832• 14 years ago

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.

Dove• 14 years ago

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?

carguy19832• 14 years ago

Oh, right, the mountains :)

Mz• 14 years ago

I think it depends where in Colorado they started and where they went after. I walked and hitched my way cross country this year. I did not go through Colorado but went up and down in altitude quite a lot. I was up around 7000 feet at least three times in states I never thought of as all that mountainous. And Cali has mountains, some of them quite high.

Laremere• 14 years ago

I'm guessing he was saying that while the chips were in transport of the passes into California, the low pressure at the high altitudes combined with the higher pressure in the chip bags would cause the bags to break open. They'd be back at normal pressure at the destination however. I also think he meant East of the Rockies as to where they were made, considering West of the Rockies is California.

johnpowell• 14 years ago

Now I know who Kettle Chips hired to make their impossible to open bags.

MartinCron4• 14 years ago

I was just thinking about how Kettle Chips have a small but pronounced notch that you can grab and pull. I haven't had any angst opening a bag of chips in a long time.

unconed3• 14 years ago

And here i was, cursing the idiot at kettle who thought eating chips from the side of the bag was a good idea. Opening from the top allows for easy reach and easy reseal.

Oxryly• 14 years ago

Not to mention the Pop Chips bags...

hammock2• 14 years ago

OK now let's find the guy that invented those crinkly Sun Chips bags.

K2h4• 14 years ago

agreed - and then lets ask them about the total fabrication that they are biodegradable.

Jimmie2• 14 years ago

Biodegradable... eventually.

edit: So I looked it up and it should only take 14 weeks in an active compost pile. I wonder if anyone has ever tested it?

bmelton3• 14 years ago

What makes you say it's a fabrication?

durkie• 14 years ago

i know them. i believe a lot of the crinklyness was actually overcome by changing to a different type of heat seal, but this was after or very close to the time when the axe was dropped on the PLA bag. but there are lots of other biodegradable materials out there.

K2h4• 14 years ago

I'm usually pretty disappointed, because on a failed opening attempt I end up crushing those chips, and then feel like I didn't really get my money's worth.

SoftwareMaven• 14 years ago

It's alright. Chips and cereal are sold by weight, not volume. Some settling (or crushing) of contents may have occurred during shipping and extraction.

K2h4• 14 years ago

I realize they are sold by weight, but I'll be honest, the full size merchandise is worth more to me. It is even worse on cereal, my wife saves the end of the box for me because i'll eat it. I prefer the full size, but throwing out the 'fluff' (crushed bits and powder at the end) seems like a waste.

glimcat• 14 years ago

"The point here is that while technical options exist to prevent premature opening of the bag, such as reducing the initial air pressure in the bag, attempting to add this to the existing processing equipment would be a nightmare. So it was necessary to increase the seal strength."

You could also reduce the air pressure in the factory, e.g. by building it in one of the aforementioned high-altitude regions.

reneherse2• 14 years ago

True, however there would be a trade off with chip cooking times, no? If water boils at a much lower temperature at high altitude, then I assume oil would as well.

But then again, you could cook your chips in pressurized vessels a la Kentucky Fried Chicken. But you'd still have to truck all your potatoes up into the mountains. Decisions, decisions...

Arelius2• 14 years ago

Building an entire new set of factories in a mountain region where there are, generally speaking, fewer residents to staff your factory is a pretty expensive decision.

ww520• 14 years ago

And/or heat up the air filling the bag. As air cools, the volume decreases.

The right solution would be to squeeze to depress the bag a bit as it's sealed. Increasing the seal strength is a quick and dirty hack, but as we've all learned too well from software, the right solutions often got trumped by quick and dirty hacks. The customers just have to live with the consequence.

jbri• 14 years ago

Your ideas have other suboptimal consequences though - sucked-in bags don't look as nice on the shelf, and in fact they look smaller. This makes them less attractive and thus less likely to be purchased.

chc• 14 years ago

That would be even more expensive than upgrading a bunch of equipment. The whole point is that the solution had to be retrofit onto existing facilities at minimal cost.

georgemcbay• 14 years ago

The guy we really need to find and punish is the one who invented "rigid plastic clamshells".

The kind that "conveniently" transforms from product packaging into a razor-sharp weapon while you are trying to open it.

AncientPC• 14 years ago

Clamshell packaging was made for retail shelves. To prevent shrinkage and increase product visibility, it was designed to be transparent while simultaneously difficult to open.

The explosion of Amazon and other online retailers made the advantages of clamshell packaging moot. However if you are a manufacturer, it may not be economically feasible to produce two different types of packaging for different retailers so lowest common denominator wins out.

Amazon has tried to combat clamshell packaging[1] with a few manufacturers (Fisher-Price, Mattel, Microsoft), but it has yet to be adopted by the rest of the manufacturing industry.

[1] http://bits.blogs.nytimes.com/2008/11/03/amazoncom-cuts-pack...

rdtsc3• 14 years ago

> To prevent shrinkage and increase product visibility,

Which is also a feature to discourage shoplifting.

retube• 14 years ago

why does clamshell pacaging prevent shop lifting? it's not like the packaging is tied to the shelf

lloeki• 14 years ago

> while simultaneously difficult to open.

I think we can all agree that someone overshot that target by a long range. Every single time I ask myself, "now how can I open this without damaging neither the package's content nor myself in the process?"

Daniel_Newby• 14 years ago

> Other options besides a stronger seal are technically possible, but not economically feasible.

It would have cost next to nothing to attach slabs of foam rubber or gentle spring plates to the sealer. As the two sides move together, the air is gently squeezed out of the bag first. Sheer incompetence.

lbo• 14 years ago

I'm not sure if I exactly understand your solution. Would you be lightly squishing the contents of the bag with the spring plates while sealing the front?

It also seems possible that manufacturers wouldn't want chip bags to look comparatively "deflated" when sold in a same-pressure environment (and thus stand out less on the shelf compared to competitors'). Also, maybe bags rupture for reasons other than pressure change and thus a stronger seal is still desirable. Just guesses, though I know the article didn't make mention of any of those reasons.

oasisbob• 14 years ago

Wouldn't evacuating the air from the packaging make the chips inside the container crush and break easier?

It's always been my understanding that the head room inside the package helps protect the contents.

Arelius2• 14 years ago

But it's not until the chips settle that this will be effective, unless you are ok with crushing chips to get the air out.

batista• 14 years ago

And who said they wanted to squeeze the air out --and have the deflated look, easy crushing and all?

When one talks about the "sheer incompetence" of a group of industry experts set to find a solution to a problem in an internet comment thread, while putting out an inane "solution" of his own that doesn't take all facts into account --and when he never knew all the constraints in the first place--, well, the Dunning–Kruger effect springs to mind...

gtani• 14 years ago

When i started skiing, I used to have bags of chips explode on me while driving from the California coast to Lake Tahoe, scared the crap out of me. I just decided to buy vacuum packed stuff up there.

biot2• 14 years ago

I find this article to be quite frustrating. It's like reading about how some process was too slow, so they looked at the variables which include a faster processor, more RAM, and larger storage. Ultimately, they chose more RAM and developed a new algorithm and all was solved. But then they never tell you what the algorithm is. Or why it allowed them to keep within the constraints of the same processor and storage.

In this case, it's a new adhesive. But how was that developed? What makes the new adhesive better suited to high-pressure applications while keeping the temperature and time constant? Inquiring geeks want to know!

masterponomo• 14 years ago

Not so difficult if you keep one pinkie nail 3 inches long and razor-sharp (as do I).

The guy who made it so difficult to open your bag of potato chips

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