Cutting speed is the speed at which the cutting edge travels over the surface of the material; it is also called "surface speed."
Its unit is m/min (meters per minute).
It is one of the basic elements of cutting conditions and has a major influence on tool life and surface quality.
A Closer Look
Cutting speed is derived from the machined diameter (D) and the spindle speed (n) using the formula Vc = π × D × n ÷ 1000.
The key point is that at the same spindle speed, the cutting speed changes with the diameter.
A higher cutting speed shortens machining time but raises the edge temperature and shortens tool life.
A common rule of thumb says that raising cutting speed by 20% roughly halves tool life.
Each material has a suitable cutting speed, and tool manufacturers publish recommended values in their catalogs.
An NC function called constant surface speed control keeps the cutting speed constant even as the diameter changes.