What Are the Differences between Five-axis Linkage and Five-axis Positioning Machining ?
When mentioning "five-axis linkage and five-axis positioning processing", it's been found that these two words sometimes confuse many people in the processing industry, so this article today is wrote to you who want to learn.
At present, most of the tasks can be completed in three axes, roughly 85% are estimated. Only the remaining 15% need to use five-axis machining, and in the five-axis machining, 3+2 machining accounts for at least 80% of the 15%, which is 12% of the total, and only the remaining 3% needs to use five-axis machining. For shaft linkage processing, the five-axis linkage here includes the situation of four-axis linkage. The main parts to be processed are impellers, blades, aviation thin-walled parts, and a few industrial design products.
Five-axis machine tools can be divided into five-axis linkage machine tools and five-axis positioning machine tools according to whether they support linked rotation motion. The difference between the two is that the latter can only meet the needs of 3+2, while the former can complete both linked and non-linked processing jobs.
3+2 positioning processing
First understand a concept of fixed axis machining and multi-axis machining.
Fixed axis machining: The orientation of the tool axis or the workpiece is fixed, and the orientation of the tool axis or the workpiece will not change during the machining process.
Multi-axis machining: The multi-axis machining is relative to the fixed axis [three axes], which means that at least one rotating axis is involved in the movement during the machining process. But note that the participation of the rotary axis in motion does not mean that the rotary axis must be linked with the translation axis to participate in the processing. On the contrary, in many cases, the axis of rotation plays a role in positioning. The processing of this is the 3+2 processing we mentioned above. The main objects of processing are most of the mechanical parts, such as automobile gearbox boxes, engine casings, etc.
During the execution of a 3-axis milling program, the two rotary axes of the 5-axis machine are used to fix the cutting tool in an inclined position, which is where the name of the 3+2 machining technique comes from. This is also called a positioning 5-axis machine because The fourth and fifth axes are used to determine the orientation of the tool in a fixed position, not continuously during machining.
The principle of 3+2 positioning processing is essentially the realization of the three-axis function at a specific angle (ie "positioning").
2. What is 5-axis simultaneous machining
According to the provisions of ISO, when describing the motion of CNC machine tools, the left-handed rectangular coordinate system is used; the coordinate axis parallel to the main shaft is defined as the Z axis, and the rotation coordinates around the X, Y, and Z axes are A, B, and C, respectively. Usually five-axis linkage refers to the linear interpolation movement of any five coordinates in X, Y, Z, A, B.
3. The difference between 3+2 positioning and 5-axis linkage:
3+2 positioning processing and 5-axis simultaneous processing are different for industry objects. 5-axis simultaneous processing is suitable for surface processing, and 3+2 positioning processing is suitable for plane processing.
The advantages of 3+2 positioning processing:
1) Shorter, more rigid cutting tools can be used.
2) The tool can form a certain angle with the surface, and the spindle head can be extended lower and closer to the workpiece.
3) The tool moving distance is shorter and the program code is less.
The limitations of 3+2 positioning processing:
3+2 positioning machining is usually thought of as setting a constant angle to the spindle. Complex workpieces may require many oblique views to cover the entire workpiece, but this can result in overlapping toolpaths, increasing machining time.
The advantages of 5-axis simultaneous machining:
There is no need for special fixtures during processing, which reduces the cost of fixtures, avoids multiple clamping, and improves mold processing accuracy.
Reduce the number of fixtures used.
Many special tools are omitted during processing, thereby reducing tool costs.
In machining, it can increase the effective cutting edge length of the tool, reduce the cutting force, improve the service life of the tool, and reduce the cost.
Limitations of 5-axis linkage:
Compared with the 3+2 positioning, the rigidity of the spindle is slightly worse.
In some cases, it is not suitable to use the five-axis solution, such as the tool is too short, or the tool handle is too large, so that the vibration cannot be avoided under any tilt angle.
Compared with 3-axis machine tools, the machining accuracy error is large.