Experimental and Statistical Study on the Noise Generated by Surface Defects of Bearing Rolling Bodies

Rolling element bearings represent a key element in machines: they are the support and the guide for rotating elements such as shafts and wheels, and, at the same time, they perform their main function of reducing the friction between two moving parts. Nevertheless, bearings can also be an important source of noise and vibration. This noise can be critical, in particular, for noise-sensitive applications. In fact, silence is becoming one of the main requirements in determining the quality of a bearing. This work analyzes the typical manufacturing surface defects of bearing balls and investigates how they affect the noise in working conditions. In particular, dedicated procedures were set up to obtain manufacturing surface defects, controlled and repeatable, according to Tsubaki Nakashima Company International Standards. The noise tester FAG MGG11 was used to study the impact of these defects on noise and vibration. The noise tester responses were analyzed to investigate the correlation between the level of noise and the severity of the simulated defects on the ball. Tests were planned according to analysis of variances (ANOVA). The influence of different defects was also investigated.