Twist drill is a tool for drilling the round hole of the workpiece through its rotary cutting relative to the fixed axis. It is named because its chip-containing groove is spiral and shaped like twist. Spiral groove has 2 slots, 3 slots or more slots, but 2 slots are the most common. Twist drill can be clamped on manual and electric hand-held drilling tool or drilling machine, milling machine, lathe and even machining center. Drill material is generally high-speed tool steel or hard alloy.