Evaluation of Tribological Properties of Hydraulic Oils by Four-ball Tester Based on Orthogonal Experiment Method

Abstract

In order to effectively evaluate anti-wear performance of hydraulic oil, four-ball tester method is used to design an orthogonal test program with 4 factors and 3 levels based on orthogonal test method, and a test method for evaluating tribological properties of hydraulic oils is established. Considering industry standards and combining with actual working conditions of hydraulic system of construction machinery, four factors of load, speed, temperature, and time have been investigated. Evaluating tribological properties of hydraulic oils by wear scar diameters, mean friction coefficient and instant friction coefficient, oil temperature and abnormal noise. The results show that under the selected factors and levels, the significant factors affecting the wear scar diameter are load, speed, temperature and time in order, the optimal test condition is load of 588 N, speed of 600 r/min, temperature of 96 °C, during time of 90 min which can effectively distinguish hydraulic oils with different quality grades. This evaluation method can provide a basis for the selection of hydraulic system oils.