Types and materials of twist drills

The twist drill is a tool that drills a circular hole in a workpiece by rotating it relative to a fixed axis. It is named because its chip groove is spiral and looks like a twist.

The spiral groove can have 2, 3 or more grooves, but 2 grooves are the most common. The twist drill can be clamped on a manual or electric handheld drilling tool or a drilling machine, milling machine, lathe or even a machining center. The drill bit material is generally high-speed tool steel or carbide.