Learning about zippers
When you wear a jacket or close your bag, there is a zip right? This mechanism has become so deeply a part of our everyday life that we often forget that it is actually a machine that was invented long ago! Have you ever stopped by to just think about how zippers work? What is the mechanism behind them?
Invented in 1917 by Gideon Sundback, a zipper comprises two rows of interlocking teeth, each of which includes a hook and a hollow. Every hook on one of the two tracks of the zipper is intended to latch into a hollow on the other track. The slider which serves as the latching mechanism, is nothing more than a group of wedges.
The first principle in use is that of the wedge --- any triangular object that has the ability to apply force perpendicular to it qualifies as a wedge. A wedge pushed between a door and its frame will apply lateral pressure on the door and the frame, simultaneously keeping the door closed.
The second principle in use is the hook --- a curved structure with a handle for holding onto anything.
If you examine the teeth closely, you will see that similar and spaced exactly the same distance apart from one another. This is important for any zip to work properly.
The teeth on the zipper track are made in a way that they can interlock with one another since they are formed like hooks. Each tooth may latch onto the one above it and the one below it with the help of the slider. Each hook is brought together at a certain angle due to the slider. This locks the hook in place before the slider moves forward.
When opening the zip, the teeth are once again angled so they may be released while the slider moves in the other direction and wedge during the slide actually pushes the teeth apart. As the force applied by a wedge is always perpendicular to it, as we already learned, the slider forces the zip's teeth sideways even as it descends.
