Evaluation of Fretting Protection Property of Lubricating Grease Applied to Thrust Ball Bearing

Abstract

Fretting wear is often the case when ball-and-roller bearings oscillate under grease lubrication. Against the backdrop of fretting wear on the wheel bearings of automobiles caused by rail transportation, the ASTM D4170 fretting test method was developed to evaluate the fretting protection property of lubricating grease. The ASTM test is conducted under a fixed load, but the load condition for industrial machines usually fluctuates. Currently, there is no international standard to evaluate the fretting wear under fluctuating load. In this study, using thrust ball bearings the authors examined 14 kinds of commercially produced greases and three kinds of originally prepared greases on fretting protection evaluation under both the ASTM test and the impact fretting test. Consequently, the authors found out the inversion of the order of fretting protection superiority between the ASTM test and the impact fretting test. As for the kinematic viscosity of base oil of grease, the amount of wear of ASTM test increases with increasing the kinematic viscosity, on the other hand the wear of impact fretting test decreases with increasing the kinematic viscosity.

Mitigation of False Brinelling in A Roller Bearing: A Case Study of 4 Types of Greases

“…Table 1 summarizes the main properties of the greases. All greases have similar density between 0.88-0.9 g/cm 3 . In this study, 4 types of new and unworked greases were used in the experiments, as this replicates the starting condition in which bearing assemblies would leave their place of manufacture.…”

“…Pittroff [19] reported that soft grease is less effective for fretting wear reduction due to its weak shear strength and adhesiveness. Contradicting results published by Yan et al [3] and Kita and Yamamoto [20] showed soft grease is more effective due to the higher uidity of the base oil. Recent work done by Maruyama et al [17] highlighted the grease with high bleed oil does not contribute to fretting wear reduction when A/D >1; because the worked thickener entered the contact and formed a layer to reduce the fretting wear.…”

“…False brinelling, a form of fretting wear, mainly occurs when a lubricated rolling bearing is stationary during transport either by sea or rail [1,2]. The identi cation of false brinelling is by the elliptical wear marks on the raceways in the axial direction at each roller position [3]. The false brinelling marks are caused by micromovements due to very low-amplitude oscillation/ vibration between the rolling elements and the raceways.…”

Mitigation of False Brinelling in a Roller Bearing: A Case Study of Four Types of Greases

“…False brinelling, a form of fretting wear, mainly occurs when a lubricated rolling bearing is stationary during transport either by sea or rail [1,2]. The identification of false brinelling is by the elliptical wear marks on the raceways in the axial direction at each roller position [3]. The false brinelling marks are caused by micromovements due to very low-amplitude oscillation/ vibration between the rolling elements and the raceways.…”

Pitch bearing/raceway fretting: Influence of contact angle

“…Vadean et al 24 concluded that the bearing wear was minimum under a certain negative clearance on the pitch wheel bearing. Yano et al 25 tested 14 types of commercial grease and 3 types of special grease with thrust ball bearings. They compared the results of the ASTM micro-test against an impact micro-test (thrust varying sinusoidally between 1.96 and 88.2 kN) to evaluate the fretting wear protection properties of these greases.…”