Vibration and sound related to bearing manufacturing

Vibration and sound related to bearing manufacturing, the most significant type of which is caused by waviness, cannot be eliminated completely. Even with modern precision machining technology, an element of waviness exists that will generate sound and vibration albeit, however, at negligible levels. It is only when waviness is abnormal (due either to factors relating to manufacturing or a particular bearing’s application) that waviness noise becomes a problem. Unlike most other sounds generated by rolling bearings, the frequency of waviness noise depends on the speed. This is an important haracteristic by which waviness noise can be distinguished from other types of noise. At a constant rotational speed, waviness noise is harsh and has a constant frequency. At CHG we say it sounds like “ooh ooh” or “whan whan.” When a bearing is accelerating or decelerating, waviness noise is

even more harsh and its frequency increases or decreases with speed. CHG’s approximation of this noise is “heeyun.” Waviness noise becomes a problem when the vibration caused by the waviness of the raceways and/or rolling elements is excessive.

Gustafsson conducted a basic study on vibration caused by waviness. He considered waviness in the circumferential direction on the surface of the inner and outer ring raceways and rolling elements as a group of sinusoidal waves. He examined the force balance inside the bearing when such waviness exists and calculated the bearing vibration caused by it. As a result, he determined the number of waviness peaks that cause vibration and the frequency of this vibration. The section of regarding the frequency of waviness noise reflects these findings. , waviness with a specific number of peaks is the cause of this vibration. vibration in the radial direction occurs when waviness with (nZ-1) peaks exists on the inner ring.

Gustafsson’s analysis of vibration was based on a constant axial load being applied and only one component having waviness. Since his research, others have analyzed cases where waviness existed on two components and radial load was applied.According to these studies,vibration occurs with additional numbers of waviness peaks. While the generation of vibration and noise with the number of peaks deduced by Gustafsson and shown in Table 1 has been confirmed in numerous cases, not enough experimental data have been gathered to confirm the additional numbers of peaks in the more recent research. To avoid problems, this vibration (waviness noise) can be reduced by decreasing the waviness in the circumferential direction on the finished surfaces of the bearing components. Additionally, it should be noted that if waviness exists on the fitting face of the shaft or housing to which the bearing is mounted, then this waviness reflects onto the raceway surface of the bearing and generates vibration. If a spline is cut on the shaft, a similar effect may

result. Therefore, careful attention is required.