CNC(Computer Numerical Control) machines are controlled by computers. By
adapting computers to the ordinary milling, lathe or drilling machine, CNC
have been developed. The operator writes a CNC program and saves on the control panel of the CNC machine tool. When the program is run, the computer evaluates the program and sends necessary signals to the motors. The motors move the table, cutting tool and make turn the spindle automatically according to the program. Cutting tools can be changed automatically writing tool change command in the CNC program. Rotary and tilting tables can be controlled by the program.