RHEOLOGICAL METHODS FOR EVALUATING THE DURABILITY OF INDUSTRIAL LUBRICANTS

The present paper describes new researches in diagnosis and performance monitoring of industrial lubricants, applying industrial logistics used to obtain an informatics device for the lubricants wear behaviour. The main purpose of the paper comes from the idea that the lubricant has to be changed when it is really used and not according to the producers recommendations. For the appreciation of the degradation stage and of the changing moment, there are made periodically physicochemical oil analyses. The oil is considered damaged when its characteristics had touched some limit values, which are established for each type of engine. The contamination level and the 'life-time' of used oil give information about the exploitation conditions, the oil quality, the construction and the technical state of engine. The paper proposes a rheometrical method for evaluation of the lubricants degradation degree, based on periodical rheometer measurements. The experimental tests show that the viscosity for motor oils decreases with the equivalent distance of the motor vehicle. An exponential relation is proposed for modelling of the law variation of the viscosity versus working time.