CNC mills use computer controls to cut different materials. They are able to translate programs consisting of specific numbers and letters to move the spindle (or workpiece) to various locations and depths.
Milling is the machining process of using rotary cutters to remove material from a workpiece by advancing (or feeding) in a direction at an angle with the axis of the tool. It covers a wide variety of different operations and machines, on scales from small individual parts to large, heavy-duty gang milling operations. It is one of the most commonly used processes in industry and machine shops today for machining parts to precise sizes and shapes.