
A Tale of Two Zippers - zdw
http://www.bunniestudios.com/blog/?p=4364
======
Animats
At 3:32 into this video

[https://www.youtube.com/watch?v=cR4S8Bqjmsg](https://www.youtube.com/watch?v=cR4S8Bqjmsg)

you can see the simple mechanism used on a similar vibratory feeder in a US
plant to separate zipper pulls facing in the wrong direction.

There are common tricks used with vibratory feeders to separate parts. That
part is wider at one end than at the other, and has a big hole and a small
hole. There are standard vibratory feeder tricks to separate them.

Custom vibratory feeder accessories, though, have to be designed and built,
which may be beyond this small shop. They're making very low end zipper pulls,
made of pot metal (zinc and aluminum) and casting them. Pot metal is really
easy to cast, but too brittle for that part. Expect those zipper pulls to
break. (There are many videos on YouTube on how to replace broken zipper
pulls.) Better zipper pulls are stamped from sheet metal - plated steel,
aluminum, brass.

The video is from a small shop that's barely surviving. It sucks making small
parts like that, because your supplier and customer are both bigger than you
and can squeeze you on price.

YKK, the world's largest zipper manufacturer, ("Small part, big difference")
offers the same pull, with no alignment projection. YKK leads in the business
because their zippers are better. There are tough engineering problems in
zipper manufacturing. They don't talk about those. There are lots of exterior
pictures of YKK plants on the web. There are no interior pictures.

~~~
jzwinck
YKK's popular Vislon model has the tabs:
[http://www.ykkfastening.com/products/zipper/slider/zipper_ty...](http://www.ykkfastening.com/products/zipper/slider/zipper_type/vislon_zipper/)
\- yet other models from them do not (e.g.
[http://www.ykkfastening.com/products/zipper/slider/zipper_ty...](http://www.ykkfastening.com/products/zipper/slider/zipper_type/metal_zipper/)).
I wonder why.

~~~
abrowne
The Vislon is a plastic zipper (i.e the zipper teeth, not the pull), so I'd
guess cheaper than the other, which is for a metal zipper. Maybe that explains
it?

------
davidbanham
This article isn't about zipper manufacturing. While the process of vibratory
sorting is interesting, it's not the point Bunnie is making.

The point as I see it is that price signalling is a frustratingly blunt
instrument.

It's annoying that so much of our species' output is channeled towards
activities that improve precisely nobody's lives. This is an artifact of how
hard it is to communicate throughout the entire stack in our modern,
globalized, decentralized capitalist economies.

That's the bit to let your engineering brain get hung up on. Not vibratory
sorter optimizations.

~~~
sukilot
I think you are overthinking it in this case. Things that look nice and feel
nice sometimes cost more.

~~~
sls
Did you read the article? He's not overthinking it, that's what the article is
about.

------
lucio
>I’d like to imagine that most people, after watching a person join pullers to
sliders for a couple minutes, will be quite alright to suffer the tiny bump on
the tip of their zipper to save another human the fate of having to manually
align pullers into sliders for 8 hours a day.

Leaving him in the street with no job...

The worker is happy that the designer don't like the "tabs". And yes, it is
more expensive, because the required manual labor.

In any case, you'll be not making him "a favor" by automatizing his job.

I'm pro-automatization, but don't paint it as "a favor" for the ones which
will be left without job...

~~~
nl
_Leaving him[1] in the street with no job..._

It's not that simple.

While I don't preclude that is a possible outcome, if you read the entire
article you see that the fact that smooth zippers are more expensive means
they can only be used on more expensive items, even though they don't give any
practical increase in quality in terms of reliability.

If those smooth zippers were as cheap to produce as the ones with bumps, then
it's possible (likely even? - after all, producers always want to
differentiate their good in some way) the decreased cost of production would
be invested in adding features that actually do something. One defensible
possibility is "mass customization" type production, which relies on each
piece being deliberately different in some way. I raise that possibility
because most would consider that type of work to be "better" than manually
threading zippers, and there could be _more_ people employed.

Clearly there are a _lot_ of things that could happen if both forms of zippers
were as cheap to produce. My point is that it is difficult to say for sure the
worker would be on the street with no job.

[1] It's more likely that the worker is actually female: Chinese factories
generally prefer to hire women. It is only comparatively recently that the
ratio pf production line workers has approached 50/50, and as recently as 2006
there were 14 men for every 100 women working on production lines in China.
See
[http://www.ft.com/intl/cms/s/0/c8948f1e-2653-11e3-8ef6-00144...](http://www.ft.com/intl/cms/s/0/c8948f1e-2653-11e3-8ef6-00144feab7de.html#axzz3RDsXy1gj)

~~~
zaroth
Obviously the manufacturer will try to optimize the BOM, and that includes the
cost of the zipper. Just as someone spent an incredible number of hours
assembling that plant, someone is also struggling over the BOM everywhere that
zipper is used. And you can bet plants that make only indented zippers with
even _less_ labor exist.

What I came away with was first, the science of plant automation is far, far
more advanced than computer science :-) Second, they've eliminated an
incredible about of manual labor already.

Using factory automation as a model, it's interesting to think how software
could do the same thing to the marketplace.

I agree with @nl, as long as the worker is there voluntarily, I don't see a
problem with a market existing for sweating the small details. The _upstream_
market competes by optimizing their BOM, so if the zipper isn't worth the
cost, it will phase out.

To argue that it _shouldn 't_ be worth the cost because the job seems to
boring for you is odd. There are many people who would be very happy to have
such a job. If and when there is a future where there does not exist a large
number of people would be overqualified for such a job, let me know.

~~~
nl
_To argue that it shouldn 't be worth the cost because the job seems to boring
for you is odd. There are many people who would be very happy to have such a
job. If and when there is a future where there does not exist a large number
of people would be overqualified for such a job, let me know._

That oversimplifies what I'm saying.

A simplified version is this: It would be better if everyone was able to
strive for self-actualisation[1] without the economic constraints that require
people to work. In the absence of that, and while there are plenty of people
at low levels on Maslow's needs hierarchy[2] who need to work, then there is
nothing wrong in wishing that the jobs they did provided some level of value
beyond being a replaceable cog in a machine.

[1] [http://en.wikipedia.org/wiki/Self-
actualization](http://en.wikipedia.org/wiki/Self-actualization)

[2]
[http://en.wikipedia.org/wiki/Maslow%27s_hierarchy_of_needs](http://en.wikipedia.org/wiki/Maslow%27s_hierarchy_of_needs)

~~~
zaroth
Sorry, I botched that comment. My last point was jumping back to critiquing
the article, not you! I should have switched the order of the last two
paragraphs.

------
aaron695
> I’d like to imagine that most people, after watching a person join pullers
> to sliders for a couple minutes, will be quite alright to suffer the tiny
> bump on the tip of their zipper.

Would I like to sack someoone after seeing them at work..... Not so much. It's
hard to sack people you have met.

Do I believe in efficiencies that will sack people I haven't met, sure.

Good article.

------
fcurella
Reminded me of when I used to work at a zipper factory, doing exactly that
job.

------
droopyEyelids
It's interesting to think of the perspective of wanting to make a product used
by billions of people every day slightly worse so some labor could be made
redundant.

~~~
eru
Why? We do that all the time.

------
sukilot
What is the mirrored plastic he mentions at the end? Sounds like the horror we
have come to know as "glossy" computer monitors.

Is it that awful fake chrome that looks like metal (and is called "chrome")
until the consumer opens the package and realizes they've been conned?

~~~
derekp7
I had an external Seagate hard drive that seemed to me that it had a high
quality look -- it was a satin finish plastic, which resembled the plastic
used on power tools. The next upgrade I got was a smooth shiny black plastic
which I hated from the beginning, as it would get scratched up too much in my
laptop bag. But guess which one most other people prefer buy?

------
aceperry
Bunnie's blog serves as an important record of the tech manufacturing world
today.

------
colanderman
I like those little bumps. They make the zipper somewhat easier to pull (more
friction = less grip needed).

------
timdierks
Seems like a really good designer working with knowledge of manufacturing
would design an aesthetically pleasing zipper pull with an asymmetry
sufficient to allow such automated orientation (e.g. one end thicker across
the width of the pull).

------
shutupalready
> _The tiny tab allows gravity to cause all the pullers to hang in the same
> direction as they fall into a rail toward the left._

The explanation above makes it sound like the pulls are getting re-oriented
(flipped around) which is not what I see in the video.

I think a clearer explanation is this:

The pulls are aligned 50% tab-right (good) and 50% tab-left (bad) as they
approach the feeder chain (or rail at the left as the OP calls it).

The tab-rights fit into slots in the feeder chain and proceed to the next
assembly step.

The tab-lefts don't fit into the slots and simply drop away into the rotating
pan below (from which they presumably return to the pot and make another
attempt at the feeder later on).

~~~
yeahboats
I think its more that the tiny tab prevents it from falling through the rail,
acting as a pivot. Gravity pulls the rest of it down.

------
Ellipsis753
I find these kind of articles very interesting. It's interesting the play you
get between "too expensive" and "worth the extra money".

It's interesting to see what's considered worth the extra effort.

------
csandreasen
Perhaps I'm missing something, but why not just put the tab on the other end
where the wearer won't grab and pull? Perhaps there's a size/perspective thing
going on with the pictures, but the tab looked small enough to me that it
wouldn't interfere with rotating the pull around the joining mechanism.

------
CephalopodMD
why not use the holes in the tab to align/hang them from along some rod or
track? That seems totally doable

~~~
joezydeco
If it was "doable", it would have been done.

How exactly do you get all the tabs on the rod? Should the tab-forming machine
put them on rods before transport to the press? Now you have to deal with rods
full of tabs and keep the press fed, plus machine jams etc.

Look at how they're moving materials around the factory. A bin full of this, a
bin full of that. Dump part A into hopper B.

------
leovonl
I was surprised to find out this had nothing to do with Haskell.

