When Fixed-Beam CNC Gantry Milling Machine When the main drive system is operating, excessive reactions in gears, bearings, and other components lead to internal transmission and radiation of noise. Moreover, abnormal conditions in these parts increase excitation forces, further amplifying the noise. So, how can bearing noise be controlled in a fixed‑gantry CNC gantry milling machine?

　　1. Control the quality of both the inner and outer rings. In the main drive system of a fault‑diagnosed CNC gantry milling machine, all bearings rotate on the inner ring while the outer ring remains stationary. Under these conditions, any radial deflection of the inner ring will induce imbalance during rotation, leading to vibration and noise.

　　If the outer ring of the bearing and the mating bore exhibit poor form and positional tolerances, radial vibration will occur, compromising the concentricity of the bearing assembly. Similarly, significant lateral runout on the end faces of both the inner and outer rings can cause the inner ring to tilt relative to the outer ring. The higher the bearing’s precision, the smaller these deflections and the lower the noise level.

　　In addition to controlling the geometric deviations of the inner and outer rings, the waviness of the raceways on both rings must also be controlled to minimize surface roughness. During assembly, strict precautions should be taken to prevent impact marks and scratches on the raceway surfaces; otherwise, bearing vibration and noise cannot be effectively reduced. Observations show that when the raceway exhibits either dense or sparse waviness, the contact points between the rolling elements and the raceways differ markedly, leading to significantly different vibration frequencies.

　　2. Control the fit accuracy of bearings, holes, and shafts on the fixed-beam CNC gantry milling machine. In this fault case… Fixed-Beam CNC Gantry Milling Machine In the main drive system, the fit between the bearing and the shaft and housing should correspond to the bearing’s radial clearance. The magnitude of the radial operating clearance depends on the interference fit between the inner ring on the shaft and the outer ring in the housing, as well as the temperature difference between the inner and outer rings during operation. Consequently, the selection of the initial bearing clearance is critical for controlling bearing noise. Excessive radial clearance increases low-frequency noise, whereas insufficient radial clearance tends to amplify high-frequency noise. Typically, it is recommended to maintain the clearance at around 0.01 mm.

　　The fit type of the outer ring significantly affects noise transmission. A tight interference fit increases sound transmission, thereby amplifying noise. An excessively tight fit can cause deformation of the raceway, leading to greater shape errors in the bearing raceways of CNC gantry milling machines and reducing radial clearance, which in turn increases noise.

　　Only proper interference fits can suppress outer-ring vibration through the oil film at the journal–bore interface, thereby reducing bearing noise in fixed‑beam CNC gantry milling machines. In addition, the geometric and positional tolerances of mating components, as well as their surface roughness, must meet the requirements of the selected bearing accuracy class. If a bearing is installed on the shaft with excessive tightness due to improper machining, shaft runout errors will be transmitted to the inner ring raceway, manifesting as increased waviness and consequently higher noise levels. Fixed-Beam CNC Gantry Milling Machine Bearing control can be achieved using the methods described above.