Vibration is one of the most troublesome problems in precision boring operations. Uncontrolled vibration generates chatter marks on the machined hole surface, deteriorates dimensional accuracy and roundness, accelerates wear of boring inserts, and even leads to tool breakage in severe cases. Precision boring demands strict surface quality and tight tolerance control; therefore, identifying vibration sources and implementing targeted suppression measures are essential to guarantee stable machining quality and extend tool service life.

Vibration occurring during boring can be divided into forced vibration and self-excited chatter vibration. Forced vibration originates from periodic external excitation. Typical triggers include unbalanced spindles, worn spindle bearings, unstable workpiece clamping, irregular cutting load caused by uneven workpiece allowance, and discontinuous cutting on cast surfaces with pores and inclusions. This type of vibration maintains a fixed excitation frequency and can be reduced by eliminating external disturbance sources. Self-excited chatter represents a more destructive form. Energy is continuously fed into the vibration system through the cutting process itself. Once the vibration amplitude reaches a critical value, obvious periodic chatter textures appear on the inner hole surface, which are difficult to eliminate simply by adjusting cutting parameters.

The boring bar is the most critical vibration-sensitive component, especially in deep-hole boring with large overhang. Slender boring bars have low rigidity, which makes them prone to bending oscillation under cutting force. Material selection directly influences anti-vibration performance. Solid cemented carbide boring bars deliver higher rigidity than alloy steel bars, yet they suffer from poor impact resistance. Vibration-damped boring bars with built-in shock-absorbing structures are ideal for long-overhang precision boring. Internal damping mechanisms consume vibration energy and effectively restrain chatter. Besides material, reasonable control of overhang length is necessary; shorten the extension distance as much as possible under process allowable conditions to improve static rigidity of the tool system.

Cutting parameter matching significantly affects vibration excitation intensity. Excessively high spindle speed may trigger resonance within the tool-workpiece system. Excessive feed rate increases instantaneous cutting force and shock load. Too small cutting depth leads to unstable light cutting and easily induces chatter. In actual production, process technicians should avoid known resonance speed bands through trial cutting. Appropriate combinations of speed, feed and cutting depth reduce cutting excitation energy and maintain stable cutting state. In addition, unreasonable tool geometry cannot be ignored. Improper front angle, clearance angle and nose radius will change cutting force distribution and increase vibration tendency.

Workpiece clamping and machine tool rigidity constitute the foundation for vibration control. Insufficient clamping rigidity allows the workpiece to shake synchronously under cutting force and forms coupled vibration together with the boring bar. Thin-wall tubular workpieces are particularly sensitive, and uniform circumferential clamping force must be adopted to avoid local deformation and vibration. Regular maintenance of machine tool spindle, guide rail and feed system eliminates clearance and improves overall dynamic stiffness. Loose connecting parts of the tool holder also amplify vibration transmission and should be inspected before batch production.