Subtractive manufacturing

Subtractive manufacturing is a process in which a material (often metal) is cut to a desired final shape and size by a controlled material-removal process.

Much of modern-day machining is carried out by computer numerical control (CNC), in which computers are used to control the movement and operation of the mills, lathes, and other cutting machines. 

The three principal machining processes are classified as turning, drilling and milling. Other operations falling into miscellaneous categories include shaping, planing, boring, broaching and sawing.