Analysing the impact of solid contaminants on grease viscosity and the theoretical temperature performance of rolling bearings

This study systematically investigates the increase in grease viscosity due to solid contamination with common industrial particles and the effects on the theoretical bearing operating temperature before plastic damage occurs. Since around 30 % of explosions in the industry are caused by non-electrical equipment, understanding the development of the ignition potential of rolling bearings at elevated temperatures due to lubricant contamination is of great importance for safety in explosion protection. Empirical data from various test series are analysed using ANOVA and regression analysis. The work results show a statistically significant correlation between contamination concentration and viscosity increase. It is, therefore, scientifically proven that an increase in contamination increases the viscosity of the lubricating grease by a factor of 2.199. The resulting theoretical temperature increase of the bearings analysed with contaminated lubricants amounts to a maximum of 2.42 K, compared to the calculation with viscosity values of clean lubricants. However, further practical investigations on a bearing test rig are necessary to determine whether the theoretical findings can be validated and further unexplored rheological and tribological factors investigated.