Drilling creates a cylindrical hole by rotating a multi-edge drill while feeding it along its axis.

A twist drill has cutting lips near its tip and helical flutes that provide space for chips to leave the hole. The centre region does not cut as efficiently as the outer lips, so axial thrust can be substantial.

Hole quality is influenced by:

• drill geometry and runout;
• machine and workpiece stiffness;
• chip evacuation;
• coolant access;
• entry and exit conditions.

Drilling is often followed by other operations because creating a hole and finishing it precisely are different tasks. Reaming removes a small amount of material to improve diameter and surface quality. Boring enlarges or corrects an existing hole with a single-point tool and can improve alignment relative to the machine setup. Tapping creates internal threads.

For a drill diameter $D$ rotating at $N$, cutting speed at the outer edge is

$$V=\pi DN.$$

The speed falls toward zero at the centre, which is one reason the centre region behaves differently from the outer cutting lips.

One functional hole can therefore require several sequential operations to achieve its diameter, location, finish and thread requirements. Hole making is a family of related operations, not a single universal drill step.