Why Do Bolts Need This Tiny Ring? The Hidden Science of Washers

That thin metal ring under a bolt looks almost useless. So why is it used in everything from heavy machinery to engines and furniture?

A washer may look simple, but it plays an important role in how a bolted joint behaves. In this video, we break down what actually happens when you tighten a bolt, how a washer spreads the load, why a flat washer is not really a locking device, and how specialized washers can help deal with vibration and changing loads.