Vibration and Sound of All-Ceramic Ball Bearings. 2nd Report. Sound Characteristics of All-Ceramic Ball Bearing, and Relationship between Sound and Vibration.

The sound of all-ceramic ball bearing having silicon nitride rings and balls was investigated and compared with those of hybrid ceramic ball bearings and conventional steel ball bearings. From the experimental results and discussion, the following results were obtained. (1) The overall sound pressure level of the all-ceramic ball bearing is influenced by the rotational velocities, and does not change with axial load. (2) In the radial direction, the overall sound pressure level of the all-ceramic ball bearing is lower than that of the hybrid ceramic ball bearing and the conventional steel ball bearing. On the other hand, in the axial direction, the overall sound pressure level is about the same with the all-ceramic ball bearing, the hybrid ceramic ball bearing and the steel ball bearing. (3) The peaks of radial and axial sound of the all-ceramic ball bearing appear in higher frequencies compared with the corresponding peaks of the hybrid ceramic ball bearing and the conventional steel ball bearing. The peaks are caused by the natural vibrations of the outer ring. (4) The sound pressure of the all-ceramic ball bearing is almost in proportion to the acceleration of the vibration.