4 Axis Milling—This cutting includes the above axes plus 1 rotary axis movement. There are two possibilities - 4 axis simultaneous interpolation (also known as true 4th axis) or just 4th axis positioning, where the 4th axis can reposition the part between 3 axis operations, but does not actually move during the machining. It is one of the most popular milling options because it allows for more detailed cutting than 3 axis. But, in recent years, its capabilities were passed by the more advanced 5 axis milling.
