Chattering is a general term for vibration that occurs intermittently during cutting. Since the occurrence of chattering leads to processing accuracy and productivity, urgent measures are required, but the cause is diverse and it is not easy to identify. Situations that are likely to be generated are poor cutting conditions, long tools, many blades, tend to vibrate, and insufficient mechanical rigidity. In this article, I will explain the cause of the chattering, which is the seed of cutting processing, and its countermeasures.
Vivi is classified into two main categories: "forced vibration" and "self -encouraging".
Forced vibration is a vibration source based on the machine itself and the external environment. A large vibration of the machine tool itself and a major vibration due to cutting resistance is expanded by the vibration characteristics of the machine.
The following tasks caused by vivi are: Finished surface deterioration Tool folding Machine damage
If a chattering occurs, there may be traces called "Vibiri Mark" on the finish of the work. When a vibel mark is generated, the finish surface deteriorates and poor processing.
Chattering often occurs from excessive load during processing, causing chipping tools on the edge of the blade and tools. In particular, for long -term processing such as molds, care must be taken because the load on tools is also increased.
Vibration due to chattering also has a heavy load on the machine itself. Therefore, if the vibration is left unchecked, there is a risk that some of the machines such as the spindle and motor may be damaged.
The occurrence of vivi has a significant effect of cutting resistance and rigidity of machinery and tools. A typical case that occurs is -if the cut resistance is large, the tools and the work vibrate -if the work is thin and the rigidity of the machine and tools may be low.
If the cutting resistance is large, the processing point of the tools and work will cause chattering points. In particular, in front of the front milling and end -milled side processing, which has a large cutting surface, it is more likely to cause chattering.
If the work is thin, the work itself will not be rigid itself and will be chattering. It is also necessary to review the work with jigs and review the processing process.
The rigidity of machinery and tools also greatly affects the occurrence of scaring. It is important to use machines and tools properly according to the type of work and processing method.
In order to suppress the occurrence of chattering, it is necessary to take measures from the initial stage of cutting, such as tool selection, setup and cutting conditions.
We will review the selection of tools such as high -rigidity tools and tools with inequality pitches and take measures to prevent them.
Uses carbide tools and high -rigidity tool holders to reduce the occurrence of chattering. To increase the rigidity of the tool, it is also important to select a tool, such as using a larger diameter or slope tool. Radias end mills have a higher rigidity than the same R -size ball end mill, so the rigidity is higher, and the tool shape has a better tapered neck shape than the long neck shape. The use of a baked holder that can be processed with a short protruding length, even in a short protruding length, with a high approach to the tools and suppressing the swing and deflection of the tools. It is effective in suppressing chattering because of its maintenance accuracy.
Inequal interval tools have the effect of suppressing vibration vibration, and the use of tools with tips and cutting -edges is effective in suppressing vivi. Distributing high -frequency vibration has the effect of preventing chattering due to cutting resistance resonance.
Choose a gentle tip with a gentle angle and move the cutting resistance in the axial direction (Z direction) to reduce the generation of scaring. It is also effective to increase the number of blades of the tools, and to increase the center of the tools and the center of the work to increase the number of simultaneous cuttings.
We will review the work during setup, such as clamps and jigs, and take measures to prevent them.
Hit the work with a plastic hammer and grasp the clamp status from the vibration. If the vibration continues for a long time, the work is weakened, and it is necessary to review jigs such as "hydraulic clamp" and "machine vise".
Assuming the load on the work, we will set up in advance in advance with anti -vibration. If the cutting resistance is applied to the vibration direction, we will review the clamp method and the clamp direction.
We will review the cutting conditions such as the cut amount and the number of revolutions and take measures to prevent it. Adjustment of cutting conditions also affects processing efficiency and finishing quality, so balance is important.
By reducing the cut amount and reducing the cutting resistance, the occurrence of chattering is suppressed. Generally, the smaller the cut amount, the less the periodic fluctuations in the cutting resistance, and the less prone to self -encouragement. It is important to note that the cut angle becomes smaller if the cut amount is too small, and the back force (force applied to the tool from the work axis direction) is generated.
By lubrication of tools and work by coolant, and reducing cutting resistance is reduced. In addition, using a high -pressure coolant has the effect of dividing the cut powder finely and reducing the friction of the tool. It is also effective when you want to increase the cutting conditions and increase the processing efficiency.
Generally, the lower the number of rotations of tools and work, the lower the cutting resistance, making it less likely to occur. Chattering occurs when a specific cutting condition overlaps, so if the rotation speed is low, it may subside by increasing the rotation speed.
In this article, we explained the causes of chattering caused by cutting and the countermeasures. The occurrence of chattering is greatly influenced by the condition of the machine tools and the environment of the factory. Therefore, in order to reduce the amount of processing accuracy by suppressing chattering, it is also important to maintain daily machinery, such as checking equipment and checking the noise.
