Numerical control (NC) is the precursor of computer numerical control (CNC), which controls the automation of machine tools and the inherent tool processes for which they are designed. The CNC machine tool is the [[servo]] [[actuator]] of the CAD/CAM (Computer Assisted Design/Computer Assisted Manufacturing) processtechnology both literally and figuratively.
CNC inherits from NC itsthe essential character of by-the-numbers interpolation of transition points in the work envelope (or Machine Coordinate System) of a mult-axis motion platform, based on the separation of programming from operations. The set of instructions (program) - usually an ASCII text file in which, in its simplest form, a line of text specifies the rectangularaxial coordinatecoordinates of a point in the work envelope of the machine determined by the stroke limits of theMachine servoCoordinate axesSystem - is prepared from a blueprint or CAD file and transferred to the memory of the CNC via floppy drive, serial data interface or a network connection. Once stored in the CNC memory and selected for execution, pressing athe appropriate key called NC Start or Cycle Start on the machine operator panel causes the CNC to execute the program.
