The word “engineer” can mean a lot of things. The word “engineering” can mean even more. Both words can be hard to relate to especially if you haven’t studied or practiced the discipline. However, it is often easier to relate to these and similar words by examining a tangible example. Many of the things we use everyday utilize multiple principles of engineering that most simply overlook. I am here to put a mini-spotlight on just one: the trusty stapler. We all know what a stapler does and how it works but what “engineering” principle went into the bringing of our powerful and hinged friend to life, figuratively speaking of course.
Good ‘ole vector statics comes into play in the form of a spring interacting with loaded staples. When the stapler is closed and not moving, an extension spring is elongated usually inside the hood of the staple chamber and provides a component of force in the direction of loaded staples. When you staple together your 20 page single-spaced research paper on naturally occurring composites, this force component slides the next staple into position ready to staple whatever other monstrosity of a report you may have lying around.
The stapler is a machine so it would be smart to assume that machine design and stress analysis are heavy hitters in the world of staplers. Individual staples are easy to remove from one another and that is because they are held together by a weak adhesive. This weak bond is important because if it were too strong, the staple would never succeed to touch the surface of your 40 page chemistry lab report that you worked on all quarter. This bond between the staples has to fail in shear, so the bar that comes on top of the staple must provide enough stress at the bond to shear away the staple from rest, through the thick stack of pages, and onto a low friction finish plate that bends the tips of the staple around the last 9 weeks of your life.
The last but definitely not the least of the engineering principles embedded inside the stapler is material science. When staples are purchased from your local stapler and stapler accessory store they are straight and bent at 90 degree angles on both ends. After being used on your 110 page Matlab project report, these angles can change to 180 degrees or more. Strain hardening occurs at the bent sections of the staple after being used which provides a more secure hold on the pages of which your deepest and most profound thoughts are printed upon.
It is important to keep in mind that the things we buy off the shelf don’t simply appear magically. Even the simplest of these things go through myriads of engineering principles before it’s ever machined or even designed. Just keep that in mind next time you’re using your cellphone or opening a door or even putting on your shoes.