CNC (Computer Numeric Controlled) Machining is the use of CNC machine tools to process metals & plastics, and also refers to the processing of CNC machining tools. CNC means CNC machine tools are programmed and controlled by CNC machining language (usually called G code). The CNC machining G code language tells the Cartesian position coordinates of the machining tool of the CNC machines and controls the feed speed and spindle speed of the tool, as well as the tool changer, coolant, and other functions.