CNC machining refers to machining whereas the machine tool operates under numerical control. CNC stands for computer numerical control. CNC machines are programmed with a cnc machining language commonly referred to as g-code. The CNC machining g-code language tells the cnc machine the Cartesian coordinates through which the cutter (end mill) should pass. The CNC machining g-code language also controls feed rates and other functions of the CNC machine such as spindle speeds, tool changers, coolant, etc.

CNC machining has many advantages over manual machining. CNC machining produces parts that are very precise and repeatable. CNC machining can produce parts with complex geometries that would virtually impossible to produce with manual machining. CNC machining technoology is widespread and most machine shops utilize CNC machining. The most common forms of CNC machining in a typical machine shop are CNC milling, CNC turning and CNC wire EDM.