The difference between 3+2 positioning and 5-axis linkage

1. What is 3+2 positioning machining

When a three-axis milling program is executed, the two rotating axes of the five-axis machine tool are used to fix the cutting tool in an inclined position. The name of 3+2 machining technology comes from this. It is also called a positioning five-axis machine tool because the fourth and fifth axes are used to determine the direction of the tool at a fixed position, rather than continuously during the machining process.

The principle of 3+2 positioning machining is essentially the realization of the three-axis function at a specific angle (i.e. "positioning"). Simply put, when the machine tool turns an angle, it still processes in the ordinary three-axis way.

2. What is 5-axis linkage machining

According to ISO regulations, when describing the movement of CNC machine tools, a left-hand rectangular 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 axes are A, B, and C respectively. Usually, five-axis linkage refers to the linear interpolation movement of any five coordinates of x, y, z, A, B, and C.

III. The difference between 3+2 positioning and 5-axis linkage

3+2 positioning processing and 5-axis linkage processing are applicable to different industries. 5-axis linkage processing is suitable for curved surface processing, and 3+2 positioning processing is suitable for plane processing.

Advantages of 3+2 positioning processing:

Shorter and more rigid cutting tools can be used.

The tool can form a certain angle with the surface, and the spindle head can be extended lower and closer to the workpiece.

The tool movement distance is shorter and the program code is less.

Limitations of 3+2 positioning processing: 3+2 positioning processing is usually considered to set a constant angle to the spindle. Complex workpieces may require many tilted views to cover the entire workpiece, but this will cause tool path overlap, thereby increasing processing time.

Advantages of 5-axis linkage processing:

No special fixture is required 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 eliminated during processing, thereby reducing tool costs.

During machining, it can increase the effective cutting edge length of the tool, reduce cutting force, increase tool life, and reduce costs.

Limitations of 5-axis linkage:

Compared with 3+2 positioning, its spindle rigidity is poor.

In some cases, it is not suitable to use the five-axis solution, such as the tool is too short, or the tool holder is too large, so that vibration cannot be avoided under any tilt angle.

Compared with 3-axis machine tools, the machining accuracy error is large.