Rolling fatigue tests of three polyglycol lubricants

Abstract

In this work, the rolling fatigue lives of three polyglycols (PAG-9, PAG-12 and BREOX-B-135X) are determined using IP-300 standard. A four-ball test machine was used and 10% life ( L 10) and 50% life ( L 50) were obtained. In addition, the stress–time curves for L 10 and L 50 were also determined. This work showed that: firstly, all polyglycols were tested under boundary lubrication regime ( λ < 1) where in rolling contacts the surface mode of failures prevails; secondly, in oils of the same family, the pressure–viscosity coefficient is relatively constant, therefore an increase in viscosity improve the minimum film thickness with the consequent increase of the λ ratio; and finally, differences in λ ratio for the three polyglycols resulted in different asperity interactions and rolling contact fatigue lives.