The 4-axis machining centre has three linear axes and a rotating table. This makes it possible to machine a cube, a cavity plate or an insert on four sides. Or a cylinder can be machined continuously all around the shell surface. With a 4-axis machining
centre one can introduce pockets and cooling holes on all four outer sides of a cavity plate. By intelligent clamping with short tools, with such a machine it is possible to mill areas on an insert which cannot be accessed with a 3-axis milling machine.
There are clearly more possibilities through the four axes than with a 3-axis machine. In Figure 1, on top, two operations are displayed from the front. The bottom figures show two operations on the right side of the cavity plate. This machining is made on both sides with just one clamping of the plate.
Figure 1: 4-axis milling [Source: Gebr. Heller Maschinenfabrik GmbH, Nürtingen]