Vibration in Machining
Throughout the machining process, vibration is a common occurrence that must be taken into consideration for the efficient, effective, and quality production of parts. Because of the unavoidable nature of vibration, knowing how and why it affects machining processes is essential for any machining operation. Vibration is an oscillating motion that occurs in a particular frequency. In a machine tool, factors such as the cutting tool, cutting process, and machine’s construction contribute to producing an effect that can be both advantageous and disadvantageous.
Due to the innate nature of vibration in machining, properly evaluating, monitoring, predicting and controlling it is essential for producing optimal results. Generally, vibration will occur in two different forms within a machine. The first form is known as chatter, which is an actual physical effect on the machining process. Chatter occurs when the cutting tool function frequency synchronizes with the natural frequency of the tool’s support structure. This synchrony causes an interference that forces the cutting tool to do more work than it was intended and disrupts the cutting process. Chatter can be recognized by regular and rapid variations in the magnitude of the cutting force generated by the tool.
The other form of vibration in a machine is known as self-induced vibration. Self-induced vibration occurs when a tool takes on an oscillatory motion during the cutting process. This vibration can lead to an unacceptable finish on the workpiece and tool breakage, which will lead to downtime and disruption in the machining process. This type of vibration is created when the cutting forces generated by the tool do not match the natural frequency of the machine’s support structure. This mismatch generates a low amplitude vibration that is difficult to detect, but can still have detrimental effects.
From these two types of vibrations, machining processes can suffer from either a low quality of cut or tool breakage as a result of the vibrations. To combat the effects of these vibrations, there are several ways that manufacturers can minimize its effects. Firstly, manufacturers should take the time to set up the machine in a way that reduces the machine’s natural frequency. In the process of setting up the machine, measures can be taken such as reducing the stiffness of the support structure or adding support to the spindle, which will reduce its resonate frequency.
Secondly, manufacturers can add vibration reducing mechanisms to their machines. These vibration reducing mechanisms can include damping materials, tuned mass dampers, and other active vibration control mechanisms. By adding damping materials to the machine, it can help to reduce the amplitude of the vibration and reduce the chances of it producing detrimental effects on the machining process.
Lastly, manufacturers can choose to switch to machining operations that reduce the cutting forces or speeds that generate useful vibration. By reducing the cutting forces or speeds, it can help to reduce the amount of vibration produced and increase the quality of the machined part.
By considering these methods for reducing vibration in machining processes, manufacturers can effectively reduce the effects of vibration on their machining operations and increase the overall quality of their machined parts. With proper understanding and consideration of the effects of vibration on machining processes, manufacturers can ensure that their machines are running optimally, efficiently, and with a higher quality level.
