"That's the second biggest zipper I've ever seen!"*



If you've taken the time to examine a zipper up close, and who of us has not, you will have noticed that pretty much all of them say: "YKK". Why is that?

Founded in Japan in 1934, YKK stands for Yoshida Kogyo Kabushikikaisha, the company that makes 45% of your zippers. Now you know. 

Sixty years later the company changed its company name to match its brand name. The YKK Group is a group of manufacturing companies and while zips are what they are most famous for, they also manufacture other types of fasteners like the kind of hook and loop fastener known by another brand name; Velcro, entrances, storefronts, curtain wall, window wall, sunshades, windows and sliding doors for office buildings, residential high-rises, schools, stadiums, shopping centers and institutional structures and industrial machinery.

They have factories in 68 countries, the largest factory producing zippers is located in Macon, Georgia where they employ 1,200 people.

The zipper is genius in its simplicity as the following sketch shows:


How Zippers Work - pichars.org
[drawing by lulz pichars]

They make use of two of six classic tools known to modern man; the wedge or inclined plane and the hook. The hook is self explanatory but the inclined plane hides itself in plain view most of the time. Screws, nails, arrowheads, knives, and so on. When chopping wood you are using two wedges. The axe itself and the wedge inserted into the cut the axe has made and splits the wood along its grain when it is hit with a maul. You're not really chopping wood, you're splitting it with the use of wedges. Any device that splits and separates is a wedge.

(or, you can skip all this text because you don't care how it works and watch the video of How It's Made at the bottom. Or skip that too, it makes no difference to me)

A zipper track is made up of dozens of teeth, each of which combines a hook and a hollow. The idea is to latch every hook on each of the two tracks into a hollow on the opposite track. The latching mechanism, called the slide, is just a collection of wedges.
As the slide moves up the zipper, the two teeth strips must enter at a specific angle. As the strips move through the slide, the slide's inclined edges push the teeth toward each other. The strips are offset from each other, so each hollow settles onto a hook in sequence. For this to work properly, each tooth must be exactly the same size and shape, and they all must be perfectly positioned on the track. This would be all but impossible without modern manufacturing technology.



Zippers that are not YKK
[photo: Rabensteiner]

[photo: Frank C. Müller]



*Maxwell Smart quote from The Nude Bomb (1980)

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