Lubricants condition monitoring by using a global performance passport

Lubricants degradation processes are characterized by the physical and chemical indicators changes for oils composition, caused by internal and external factors and the operating conditions severity. Lubricants condition monitoring involves experimental methods to study their behaviour, for developing a lubricants life cycle assessment methodology. The paper proposes the lubricants behaviour complete characterization by using a global performance passport, to study the rheological, tribological and microscopic properties, for various wear stages. The global rheological lubricant feature is expressed by the maximum film pressure, by using the original rheological experimental module. The reference rheological lubricant feature is obtained by using the viscometer validation module, based on the variation of viscosity by the temperature. The tribological lubricant feature is given by the tribological experimental module, based on friction coefficient variation according to the normal pressing force and sliding speed. The structural microscopic lubricant feature is shown by the wear particles analysis module, analysing the solid particles type identified in the fresh and worn lubricant. The global performance lubricants passport assess the lifetime reserve, function the specific use conditions, to reduce operating costs. To do the initial investment for the preliminary experimental tests conduct it is recommended to determine the economic profitability threshold for the user investment.