Wear particles and contaminants are known to reduce lifetime of machine elements such as roller bearings. This can be avoided through fine filtration. However, oil filterability can change in service, and in case of exceeding the maximum pressure at the filter, contaminated oil can flow through a bypass, threatening the function of the lubricated components. The purpose of this study is to provide a cost-efficient method to estimate the long-term oil fine filterability.
The estimation of long-term oil fine filterability takes place in two steps. In the first step, oil in its original condition is subjected to different stresses to reproduce changes experienced in service within a relatively short period of time. In the second step, the resulting oil is subjected to filterability tests. Existing test methods were adapted to produce realistic oil changes and deliver a realistic evaluation of filterability.
Oils produced using metal-catalyzed thermal-oxidative stresses and humid air are similar to real oil samples from the point of view of nuclear magnetic resonance oil analyses and filterability tests. Test conditions suitable for highly viscous gear oils were derived considering operation at low and high temperatures.
The test method provides an estimate of deterioration of oil filterability in service through a comparison between the filterability of oil in original condition and the filterability of an artificially produced oil.
