Brief Information About Grinding Tools The grinding tool is the most important tool in the workshop. It is used to grind and polish the surface of metal and other materials. The grinding machine can be divided into three types: hand-operated grinding machine, electric grinding machine, air-powered grinding machine. Hand-operated grinding machine is usually used for small workpieces; electric grinding machine is mainly used in precision machining; air-powered grinding machines are widely used in metalworking industries to grind all kinds of metal materials. Grinding tools are all about versatility. They can grind metal, cut tile, stucco and pavers, rout out mortar, and sand, polish and sharpen. And there's nothing better than an angle grinder for getting a lot done quickly.