Similar to end mill action, the cutting edge of the blade comes in contact with the metal, and actually rips material away. Of course, this is on a microscopic level. Each blade tooth removes a small amount, and the next tooth will continue in the cutting action.

Saw blades will wear out, just as any other cutting tool. Examining the blade is critical before beginning any major cutting job. Signs of wear include shiny spots in the otherwise dark metal of the blade. The edge of the tooth will be rounded, and there may be broken teeth as well.