Multi Parameter Sliding Test Result Evaluation for the Selection of Material Pair for Wear Resistant Components of a Hydraulic Motor Dedicated for Use with Environmentally Friendly Working Fluids

Abstract

In the paper the method and results are presented of the testing of tribological performance of a number of hard materials available commercially. The tests consisted in unidirectional sliding with liquid lubrication. The load and velocity regime chosen were similar to a standard four-ball lubricity test with constant velocity and load increasing over time. The regime was modified in such a way that over the initial part of the test both the velocity and load were linearly increased until a certain stable level of each input parameter was reached and the test was then continued till the termination due to chosen criteria. The materials used were high alloy tool steels and sintered carbides, normally used in working of metals by cutting. The lubricants environmentally inert or friendly fluids: water, mineral oil-in-water emulsion and vegetable oil. In the tests, typical sliding friction parameters were recorded, later evaluated on the basis of multiple parameters observable within the test such as e.g. maximum load and velocity reached, calculated maximum surface pressure or presence and amplitude of friction induced vibrations. In the group of material/material/lubricant combinations a ranking was created for each parameter in the assessment set by awarding points for performance. Best performance was granted the least amount of points. Overall performance was then judged by the accumulated number of points. The materials, which were evaluated as performing best have been chosen as input materials for the design and manufacture of a prototype motor for later laboratory and field testing.