How to solve the low Frequency Vibration of NC Lathe

In the process of machining, the CNC lathe sometimes produces low-frequency vibration, which will lead to workpiece surface vibration, high rework rate and high scrap rate. 

At this time, pay attention to find out the specific reasons, and then take corresponding elimination measures. 

This will ensure normal work. 

1.In the low frequency vibration, the vibration is mainly due to the change of the cutting force caused by the vibration in the Y direction, which makes the F phase separation > F close. 

Measures: the larger the tool entry angle (μ r angle), the smaller the Fy force, the less the possibility of vibration. 

Therefore, appropriately increase the entry angle of the tool, eliminate or reduce the vibration, and appropriately increase the front angle of the tool to reduce the Fy force, so as to reduce the vibration. 

If the back angle of the tool is too large or the cutting edge is too sharp, the tool can easily bite into the workpiece. 

Tremble. 

After the tool is passivated correctly, its side can prevent the tool from "biting" into the workpiece, thus reducing or eliminating vibration.

2. When wide and thin chips are produced in the turning process, the vibration in the Y direction will cause the change of the cutting force. 

When the cutting part is wide and thin, the vibration in the Y direction will lead to a sharp change in the cross-sectional area and cutting force of the cutting. 

Therefore, in this case, CNC machine tools are easy to vibrate. 

For example, in longitudinal turning, the greater the cutting depth, the greater the feed speed, the smaller the entry angle, the wider and thinner the cutting part, the easier the vibration. 

Therefore, when selecting the rotation speed, avoid the medium speed area where the cutting force decreases with the speed (when cutting carbon steel, the speed range is 30-50m / min). 

At the same time, reducing the turning force and properly increasing the feed speed and reducing the cutting depth are also helpful to restrain the vibration. 

3. The lack of rigidity of workpiece system and tool holder system is the main reason for low frequency vibration. 

The following measures can be taken to eliminate or reduce vibration: when clamping the workpiece with three or four clamps, try to make the rotation center of the workpiece and the rotation center of the spindle as large as possible, the coaxiality error of the CNC lathe is small, and the vibration caused by the periodic change of cutting force caused by the tilt and intermittent cutting or uneven cutting of the workpiece machined by the NC lathe is avoided.