How are the four axis and five axis commonly used in machining centers distinguished, or what is the difference?

Four axis machining center: It adds a rotating axis on the basis of three axes. The axis that rotates around the X axis is called the A axis, and the axis that rotates around the Y axis is called the B axis. Through rotation, multi-faceted machining can be achieved, reducing the number of clamping times and improving machining consultation. Four axis machining centers are advanced models with slightly higher prices.
Five axis machining center: It adds two rotating axes on the basis of three axes, which can machine any surface of the workpiece other than the fixed surface. Five axes are still divided into true five axes and "false five axes" in the industry. The difference is not whether the five axes can be linked, because "false five axes" can also achieve five axis linkage. The fundamental difference lies in whether there is RTCP, that is, tool tip following function. Machine tools with RTCP function can be programmed directly using the tool tip without considering the distance of the rotating axis center. When programming, only the workpiece coordinates need to be considered, without considering the spindle swing length and rotating table position. Five axis machining centers have high technological content and precision, and are top-level equipment in the machining field. Of course, the price is also the highest.

-Introduction to Five Axis Machining

Five axis machining center is a high-tech and high-precision CNC machine tool specifically designed for machining complex curved surfaces. This type of machine tool has a significant impact on industries such as aerospace, scientific research, precision instruments, and high-precision medical equipment. Currently, five axis linkage machining center is a favorable means to solve problems such as impellers, blades, marine propellers, heavy-duty generator rotors, turbine rotors, and large diesel engine crankshafts.

The five axis machining center has the characteristics of high efficiency and high accuracy. The front end of the spindle is a rotary head that can rotate 360 ° around the Z-axis on its own, called the C-axis. The rotary head also has an A-axis that can rotate around the X-axis, generally up to plus or minus 90 °, achieving the same function as above. The advantage of this setting method is that the spindle machining is very flexible, and the worktable can also be designed to be very large. Large aircraft bodies and car shells can be machined on this sharp machining center. This design ensures that when using a spherical milling cutter to machine curved surfaces, when the tool centerline is perpendicular to the machining surface, the surface quality of the workpiece cut by the vertex will be poor due to the zero vertex linear velocity of the spherical milling cutter. Therefore, the spindle can be rotated by an angle relative to the workpiece, allowing the milling cutter to avoid vertex cutting and ensure a certain machining speed, which can improve the surface machining quality of the part. This structure is very popular for high-precision surface machining of molds, which is difficult to achieve with old-fashioned machining centers. In order to achieve high precision in rotation, high-end rotary shafts are also equipped with grating feedback, and the indexing accuracy is within a few seconds. Of course, the rotation structure of such spindles is relatively complex and the manufacturing cost is relatively high.
The five axis linkage machining technology requires five independent axes to perform CNC interpolation motion together on a complex shaped surface in order to obtain smooth and smooth machining technology. Although theoretically any complex surface can be described using X/Y/Z three-axis coordinates, the actual machining tool is not a point, but a solid with a certain size. In order to avoid interference between the tool and the machining surface during space distortion machining and ensure consistency in cutting conditions at various points on the surface, it is necessary to adjust the angle between the tool axis and the surface normal in two dimensions.
The number of axes in a five axis linkage machining center refers to the number of axes that need to move independently when machining the same surface, rather than the number of controllable axes owned by the CNC.

-What is five axis machining? What are the coordinate axes?

Five Axis Machining is a mode of CNC machining.
According to ISO regulations, when describing the motion of a CNC machine tool, taking a five axis linkage training machine tool as an example, a right-handed Cartesian coordinate system is used; The coordinate axis parallel to the main axis is defined as the z-axis, and the rotation coordinates around the x, y, and z-axis are A, B, and C, respectively. The motion of each coordinate axis can be achieved by the worktable or the movement of the tool, but the direction is defined by the direction of the tool's relative motion to the workpiece. Usually, five axis linkage refers to linear interpolation motion of any five coordinates in x, y, z, A, B, and C.
In other words, the five axes refer to the three moving axes of x, y, and z plus any two rotating axes. Compared to the common three-axis (x, y, z degrees of freedom) machining, a five axis machine tool refers to a tool that can be positioned and connected in five degrees of freedom when machining parts with complex geometric shapes.
The machine tool used for five axis machining is usually referred to as a five axis machine tool or a five axis machining center. Five axis machining is commonly used in the aerospace field to process body components, turbine components, and impellers with free-form surfaces. Five axis linkage CNC machine tools can process different sides of workpieces without changing their position on the machine, greatly improving the processing efficiency of prismatic parts.