With the development of machining technology, the application of multi-axis CNC machining centers in enterprises is also increasing， it is also an inevitable trend for the future development of enterprises to high-end. According to the actual needs of enterprises, let’s learn the application scope of the four axis CNC machining center. (1) Four-axis machining center is suitable for polyhedron machining; (2) Four-axis machining center can be used for helix (cylindrical oil groove), spiral groove, cylindrical cam machining with rotation angle; (3) Four-axis machining center is suitable for blade machining. China is a big manufacturing country, the application of the fourth axis is developing rapidly, and there is a great demand for the fourth axis components in the market.

1.  Four axis machining center for polyhedron machining method

Four-axis machining center is mainly to add the fourth rotating axis on the basis of the original vertical CNC machining center or horizontal CNC machining center. Generally, a rotating shaft is added to a table surface parallel to the axis of the X-axis, which is defined as the A-axis. When machining polyhedron parts, the machining surface of polyhedron should be parallel or perpendicular to the worktable after rotating around the axis A, otherwise, the machining surface will be incomplete and undercut or overcut. The machined parts are mounted on the A-axis rotating table by fixture to keep the rotating axis of the workpiece parallel to the axis of the A-axis and to correct the datum plane. In actual machining, the relative position of the machining surface can be realized by rotating the angle, and all the graphic elements in the machining plane can be processed completely.

2.  Four axis machining center for revolving contour 

The revolving contour of the part mainly includes the contour of cylindrical rotary oil groove, cylindrical cam revolving around the central axis. The processing of cylindrical oil groove mainly depends on the rotation of the A axis (4th week) and the movement of the X axis in the same time. The processing of cylindrical cam is achieved depends on the two-axis control between A axis and X axis.

Figure 1 is a typical multi axis machining partAccording to Fig. 1, it can be seen that the part contains machining work in several position and milling of spiral grooves. For the pixels in the angular direction of the workpiece shown in Fig. 1, if by a general CNC machining center (without the fourth axis), it may need to be clamped in many times , and it cannot guarantee the accuracy of the workpiece geometric tolerance, and the machining efficiency is low. If use a machining center with the fourth axis, the machining of holes and grooves can be realized by simple program control, it can not only save machining time but also ensure the machining accuracy, the program is showed Table 1.

Table 1: The part processing program for Fig. 1

According to the program in Table 1, it can be seen that machining is not complicated, but the main function of A in the program is to play a role in positioning. The above graph element can also be processed on a general CNC milling machine, but the spiral groove below cannot be processed without a machining center without fourth axis.   

The spiral groove in Fig. 1 is on the surface of the outer circle. The spiral groove machining can be completed only when the workpiece rotates and moves along the X-axis simultaneously, so In this program, A axis and X axis should achieve two-axis control. Its program shown in Table 2.

Table 2: spiral groove processing program

Multi-axis CNC machining center programming is mainly based on the original three-axis programming to add a rotating shaft to control workpiece rotation to complete all the graph elements in different surface in one position and clamp.

It can be said that the birth of multi-axis control technology represented by four and five axes has made a qualitative leap in machining level. CNC machining centers have penetrated into more and more fields such as fixture and die industry, machining of mechanical parts, carving of handicraft, medical equipment industry, and automotive aerospace parts and so on. As mechanical industry practitioners, we have reason to believe that CNC machining center will be better tomorrow.