Milling refers to the use of rotating multi edge cutters to cut workpiece, which is an efficient processing method. When working, the tool rotates (as the main motion), the workpiece moves (as the feed motion), and the workpiece can also be fixed, but at this time, the rotating tool must also move (completing both the main motion and the feed motion). Milling machines include horizontal or vertical milling machines, as well as large gantry milling machines. These machines can be ordinary or CNC machines. Machining using a rotating milling cutter as a cutting tool. Milling is generally performed on a milling or boring machine, suitable for machining flat surfaces, grooves, various shaped surfaces (such as splines, gears, and threads), and special shaped surfaces of molds.

Milling is a mechanical processing method that uses a milling cutter as a tool to process the surface of an object. Milling machines include horizontal milling machines, vertical milling machines, gantry milling machines, profiling milling machines, universal milling machines, and bar milling machines. The characteristic of curved surface parts is that the machining surface is a spatial curved surface, and during the machining process, the machining surface and the milling cutter are always in point contact. Ball end milling cutters are often used for surface finishing.