Bearings may produce slight operational sounds during operation. However, excessive noise, abnormal sounds, or impact noises indicate bearing failure.

The causes of noise in deep groove ball bearings are complex. One factor is wear on the mating surfaces of the inner and outer rings. This wear disrupts the alignment between the bearing and housing, or between the rolling elements and shaft, causing axial displacement. At high rotational speeds, this misalignment generates abnormal noise. Furthermore, surface metal spalling due to bearing fatigue increases radial clearance, contributing to noise. Additionally, insufficient lubrication causing dry friction, bearing fracture, or other damage can produce abnormal sounds. Loosening and damage to the cage following bearing wear and play can also generate unusual noises.

Bearing raceway noise and its control methods

Raceway noise is a smooth, continuous sound produced when the rolling elements move along the raceway surface during bearing operation. What types of bearing seals exist? This constitutes the fundamental characteristic sound common to all rolling element bearings. Typical bearing noise comprises the combined effect of raceway noise and other contributing sounds.

The raceway noise of ball bearings exhibits an irregular pattern, with frequencies exceeding 1000Hz. Its fundamental frequency remains constant regardless of rotational speed, though its partial sound pressure level increases with accelerating rotational speed. For bearings with pronounced raceway noise, the sound pressure level decreases with increasing viscosity. Conversely, for bearings with minimal raceway noise, the sound pressure level increases rather than decreases when viscosity exceeds approximately 20 mm²/s. Greater housing rigidity results in a lower sound pressure level for raceway noise. Should radial clearance be excessively small, both the partial sound pressure level and dominant frequency of raceway noise increase sharply with reduced clearance. Methods to control raceway noise include: selecting low-noise bearings with minimal waviness, and carefully evaluating operating conditions. Raceway noise frequently influences overall machinery noise levels; reducing it consequently lowers system noise.

Impact noise from rolling elements and its control methods: In larger ball bearings or deep groove ball bearings operating at low speeds under pure radial loads, the centrifugal force on rolling elements is minimal. Consequently, rolling elements in the non-load zone may impact the cage or raceway, generating noise. However, this type of noise diminishes as rotational speed increases. Control methods for rolling element impact noise include: appropriately reducing radial clearance and employing bearings with cages featuring rational structures and materials possessing adequate elasticity.

Rolling noise in bearings and its control methods Rolling noise is a harsh, metallic friction sound that can occur in bearings under all operating conditions. It predominantly arises in larger-sized, grease-lubricated bearings and is more likely to occur in greases with degraded base oil properties. It is virtually absent in oil-lubricated bearings. Furthermore, it is less likely to occur during winter months. When subjected to pure radial loads, it tends to manifest more readily in bearings with larger radial clearances. Its occurrence is also influenced by bearing size, frequently arising within specific rotational speed ranges, and may present either continuously or intermittently. Special machining techniques applied to the outer raceway can prevent rolling noise. Where necessary, such bearings may be selected, or the radial clearance may be appropriately reduced. Furthermore, the use of high-performance grease and enhancing the rigidity of components mating with the bearing can mitigate this issue.