Research on turning technology of large aspect ratio micro-axis (4)

Figure 5 The end diameter is 7μm fine axis

Figure 6 Micropores with a diameter of 19 μm

Figure 7 SEM photograph of the slightly elongated shaft

A Ø11 μm axis was used as a electrode, and a scanning electron microscope (SEM) photograph of Ø19 μm micropores was processed on a gold foil having a thickness of 20 μm. The voltage used for EDM is 110V, the discharge capacity is 100pF, and the positive polarity is processed. The Mobil electric machining fluid is used, and the processing time is about 10s.
Scanning electron microscope (SEM) photograph of a 20 μm nominal diameter and a 1 mm long elongated shaft.

The microstructure of the head, the middle, and the root observed under a scanning electron microscope at a magnification of 2480 times. The SEM measurement results showed a head diameter of 18.5 μm, a middle diameter of 18.9 μm, a root diameter of 19.7 μm, and an average diameter of 19 μm. The measured length was 1030 μm, and the diameter values ​​differed by 1.2 μm in this range, and the aspect ratio was about 55. The finishing time takes only about 2.5 minutes, which is more efficient than EDM. Based on the turning of the fine shaft, the research on the fine thread turning technology was also carried out. The same tool as the turning micro-axis is used, except that the tool needs to be rotated 16.5° when the tool is installed, so that the thread cutter has equal main and auxiliary declination. Other cutting conditions are the same as for turning fine axes. First, the cutting quality of the spindle at different speeds was tested. The thread cut at the speed n=500r/min was observed by an optical measuring microscope, and the thread surface was rough, and the actual height of the thread was uneven. After the speed is increased to n=2000~3000r/min, the thread profile of the cutting is clear, and the size index is basically consistent with the set value. Therefore, in the process of fine thread processing, a higher rotational speed is required. Then, the limit size of the fine thread having a pitch of 10 μm was tested. Cutting parameters: spindle speed n=2000r/min, back-feeding amount ap=1～2μm, feed amount adopts f=5mm/min. The minimum thread diameter that can be achieved with different thread lengths. As can be seen from the figure, as the length of the machined thread is shortened, the minimum thread diameter that can be achieved is also reduced.

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