On the application of the mechanical aging Master Curve for lubricating greases to rolling bearings

Understanding the mechanical degradation of grease is crucial for the development of grease life models and to predict grease leakage from bearings. It was found recently that this process can be described using a Master-Curve where the yield stress is given as a function of the imposed energy corrected for temperature using an Arrhenius equation. This paper shows that this concept can be applied to the mechanical degradation of grease in rolling bearings provided that the oil content in the grease has not changed. So it does not apply to those areas in the bearing where the centrifugal forces are high such as under the cage/inside the running track. However, it does apply to the grease that is aging in the unswept area of the bearing, i.e., the area in the bearing where the grease undergoes moderate shear. This Master-Curve makes it possible to develop a remaining grease life model for bearings operating under moderate temperatures.