As the knob is turned, the feed wheel grips the lip. Then the opener cuts through the lid. The can rotates naturally as you work your way around. Continue turning the knob until you've cut the lid around the entire can or left a tiny bit uncut.

How does a can opener function?

A can opener (also known as a tin opener) is a device used to open steel (not tin) cans. ... Most can openers press a cutting wheel into the edge of the lid while a rough support wheel presses up under the lip of the can. It is best to purchase a can opener that drives this support wheel to provide easier motion.

How does a mechanical can opener work?

When you force the cutting wheel against the metal of the can by pushing the handles of the opener together, its sharp edge cuts through the metal. When you turn the traction gear by rotating the gear, the cutting wheel rotates as well, cutting through the metal as it advances around the lip of the can.