In the production and inspection process of wire EDM machines, using the octagonal cut test to determine the machine's accuracy is an excellent method. It comprehensively reflects the machine's coordinate displacement accuracy, the smoothness of the guide wheel operation, the system backlash in X and Y axes, and the fidelity between the feed and actual displacement. Any accuracy-related defects in the machine are revealed during the octagonal cut and cannot be artificially concealed.
The resulting eight-sided cut should be analyzed from the following aspects:
1. The two straight planes parallel to the X-axis are smaller in size and have a slower feed rate, indicating that the axial yaw of the guide wheel is relatively large, resulting in a larger kerf.
2. The two straight planes parallel to the Y-axis are smaller in size and have a slower feed speed, indicating that the radial yaw of the guide wheel is large and the chuck is larger.
3. The presence of two straight, parallel-to-the-X-axis corrugated surfaces indicates that the wire does not follow a single trajectory in the Y-axis direction during its up-and-down movement. (The extensions of the "V"-shaped grooves on the upper and lower guide rollers are not a single line, hence the corrugated pattern occurs periodically when the wire reverses direction.)
4. The presence of two straight, parallel-to-the-Y-axis serrated patterns indicates that the yarn does not follow a single path in the X-direction during upward and downward movements, resulting in a significant difference in tension between the two directions. (The serrated pattern is cyclical, revolving around the yarn's reversal.)
5. The inconsistency between the upper and lower ends of the cutting surface indicates that the positioning effect of the "V" groove in one of the upper and lower guide wheels on the molybdenum wire has significantly deteriorated.
As mentioned above, cutting any shape makes it difficult to clearly expose all these features. Therefore, Baoma Machine Tools uses an octagonal cutting method to inspect the machining accuracy of its machine tools before shipment, demonstrating Baoma's superior machine tool quality and its belief that "quality is life."
