The computer numerical control machines (CNC) realize the component starting from a piece of material that is worked removing portions of material. This type of processing is called "chip removal"; lathes and milling machines are the two main type of CNC equipment. Lathes cut workpieces while they are rotated, according to the geometry that is set by the numerical control system. On the contrary, milles move the spindle (or workpiece) to various locations and depths. Thanks to the increase in computing capacity, modern 4 and 5 axis machines combine the characteristics of the two processes described above. Thanks to the simultaneous mouvement along 3 linear and 2 rotation axes, the machining tool cuts the workpiece without limits realizing extremely complex shapes. All the axes can have the ability to interpolate between them in a continuous way allowing the processing of complex surfaces such as the turbines of aero-engine turbines.
To carry out similar works, the machine is managed by a CAD / CAM software. The component to be realized is first designed with a CAD program, after that, it is transformed into a virtual processing cycle with a CAM software. At the end, a program called 'post-processor' translates the model into instructions for the CNC machine which create the component without the need of operators.