Near-race ultrasonic inspection of tapered roller bearing components for non-metallic defects

Bearing steel cleanliness is directly linked to failures caused by the interaction of subsurface defects and rolling contact fatigue (RCF). Optical analysis of as-received steel coupled with ultrasonic inspection on finished components minimizes the occurrence of defects in the near race. While useful as a preventative measure, these methods do not ensure that critical areas of components subjected to RCF are free of defects that act as stress concentrators and contribute to premature failure. This presentation provides a brief summary of the current technology and standards utilized in the industry. The deficiencies of the current methods for the particular case at hand are identified and a surface wave scanning method is introduced. The development and production of reference parts for this type of scanning are then discussed. The production method entails both traditional electro-discharge machining (EDM) and femtosecond laser machining (FLM) on finished bearing components such that the reference part microstructure resembles that of a finished part. Experimental results utilizing surface wave scanning are given for two types of assembly-ready bearing components that are then subjected to realistic service loads and mileage to the point of failure. The results of the service life simulations are then correlated with surface wave scanning results and are shown to be in good agreement. This work is anticipated to impact any field in which components are subjected to RCF.