How, exactly, do zips work?

Question

I don't understand how dragging the little zipper thing across makes the zip teeth thingmys close together and not come apart.

Answer 1

The zipper slider portion brings the teeth in along a curved path as they enter. If you take a zipper and bend it sideways you will see the spacing increase between the teeth.

Once the teeth are separated a little it's an easy task of meshing them and then allowing them to straighten back out (as they exit). Once they do, the teeth are locked together. You can see tiny little bumps and divets where the bumps mesh with the divets. These prevent the teeth from simply slipping apart once they are together.

The plastic zippers use a slightly different way to create the teeth and locking action. If you take a tiny piece of plastic line and kink it, you will see that it creates a sort of flat spot that is 'pointy' on each end. These are the teeth and locking mechanism needed to make the zipper work, then all you need is that pretty kewl little slider to run up and down to lock and unlock the teeth, allowing you to 'zip up' your garment when it's cold, or unzip it to remove it.

Hope that helps.

The snap below isn't as good as I wanted, but it gives you an idea. You can see how the teeth would mesh and you can see the protrusions used in this case to help keep the teeth locked.

Answer 2

It's hard to explain clearly without a diagram, but basically there are to wedges, an upper and a lower, inside the "slide" (the thing you pull up or down) that force the teeth together. It would be impossible to make a zipper without modern technology because the teeth need to all be exactly the same size. If you want to see a diagram go to http://science.howstuffworks.com/zipper2...

and click on the "click here to open" thing in the box