During lubricant operation temperature, pressure and load are well known as the main factors enhancing degradation. To monitor this degradation process in lubricating oils, the industry has defined specific test methods involving correct sampling techniques and analytical techniques to provide efficient information on the correct oil change interval. Moreover, modern oil-lubricated systems apply specific oil monitoring procedures as part of condition based maintenance practices to detect root cause failures and prevent equipment damage. Applying these condition monitoring practices on lubricating greases is much more complex as once these greases are put into service, it becomes rather difficult for end-users to perform on-site grease condition monitoring, and define the correct frequency for re-greasing bearings. This explains why industry relies for grease-lubricated systems procedures on time-based intervals (preventive maintenance). In this study, research was performed, using a grease based on mineral oil and lithium soap thickener. Additional research was performed on the polyurea type of grease, in order to define the possibilities of monitoring antioxidants in polyurea greases. The greases were oxidized to produce samples at different intervals in order to evaluate different techniques, more specifically: Acid Number (AN), LSV (linear sweep voltammetry - RULER) and FTIR on the grease and its corresponding oil, viscosity, ICP and DSC. Beside the maximum information that the selected analytical techniques should give on the grease condition, the program has also evaluated the minimum quantity of sample, minimum time and the cost of analysis. During the study, different technologies available on the matter have been compared, which allow the optimization of the frequency of grease changes. Below are shown the different techniques used and the results obtained.
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