How To Control Vibration During Cutting During CNC Machining?Cutting vibration usually occurs in turning of slender shafts, turning of thin-walled parts, etc. Once the vibration intensifies, there will be intense vibration with an amplitude exceeding several tens of μm, usually accompanied by a large amount of noise. In the cutting process, the vibration may exceed 100μm. Although it can be processed, there will be obvious vibration scratches on the machined surface, which is not allowed on the finished surface.
Hazards Of Cutting Vibration
Vibration in metal cutting is a very harmful phenomenon.
- 1. Affecting the surface quality of parts If vibration occurs during processing, there will be relative displacement between the tool and the workpiece, which will cause vibration marks on the machined surface, seriously affecting the surface quality and performance of the parts;
- 2. When cutting vibration of the machine tool and tool life is reduced, the process system will continue to bear the action of dynamic alternating loads, the tool is easily worn (even chipped), the connection characteristics of the machine tool are damaged, and even the cutting process cannot be continued in severe cases;
- 3. Noise is harmful to the health of the operator The noise generated in the vibration will also endanger the health of the operator. In order to reduce the vibration, sometimes the cutting amount has to be reduced, which reduces the production efficiency of machine tool processing.
Therefore, in order to ensure the normal operation of such machining equipment, the control of cutting chatter becomes more and more important.
The Causes Of Cutting Vibration
For the tool to vibrate when cutting the workpiece, the following three conditions must exist at the same time:
- The first is that the rigidity of the process system including the tool is insufficient, resulting in its low natural frequency.
- The second is that the cutting generates a sufficiently large external force,
- The third is that the frequency of the external excitation force is the same as the natural frequency of the process system and then resonance occurs.
How To Eliminate Cutting Vibration
- The first is to reduce the cutting force to a minimum,
- The second is to maximize the static rigidity of the tool system or fixture and the workpiece;
- The third is to create another vibration inside the tool holder to disrupt the vibration frequency of the externally excited cutting force, thereby eliminating tool vibration.
1. The first is to reduce the cutting force to a minimum
- (1) Use a sharp blade to reduce cutting force
- (2) When the depth of cut is constant, use a small tool nose arc radius
- (3) For boring tools with slender shanks and turning slender shaft parts, 90-degree leading angle tools should be used
- (4) For milling cutters with slender rods, circular blade milling cutters are the most beneficial for vibration reduction.
- (5) The plunging method is often used when aluminum cnc milling deep cavities with slender rod end mills
- (6) The face milling cutter adopts sparse tooth unequal distance milling cutter to reduce milling vibration
- (7) The smaller the blade edge angle, the better
2. Improve the static rigidity of the tool holder (Static Toughness)
Use solid carbide or heavy metal toolholders to improve the static rigidity of the toolholder 3. Improve the dynamic rigidity of the tool—passive damping and vibration-isolating toolholders
3. Improve the dynamic rigidity of the tool—passive damping and vibration-isolating tool bar