Solution:

Computer numerical control, or CNC machining, is a computer-aided, high-accuracy manufacturing process. Pre-programmed CAD software is used to automate the controlled machining and eliminate the need for an operator.

NC machines switched over the controlling from the electronic HW system control to the computer control due to the advent of computers.

The use of computers emphasized controlling the NC with advanced software using sophisticated computers instead of HW.

It is an NC system were a dedicated stored program and computer are used to perform the same or all of the basic NC functions by a control program stored in the computer.

This drastically reduces human error during the controlled machining process and allows for high accuracy manufacture of the different parts. Another benefit of CNC machining is consistent and accurate workpieces.

In CNC a mini-computer is used to control the machine tool functions from stored information's or punched type input or a computer terminal input.

CNC machine = NC machine + a computer

CNC needs only the drawing specifications of a part to be manufactured and the the computer automatically generates the part program for the loaded part.

CNC is used when the control system of the NC system utilizes an internal computer.