In this paper, the effect of slide-to-roll ratio (SRR) on coefficient of friction was investigated. Measurements were taken from a lubricated contact between a polymer ball and steel disc. The experiments were carried out on Mini Traction Machine, which allowed setting of any SRR and also managed to change SRR during tests. That way, all other parameters in the contact remained unchanged for full duration of tests. Raw data, measured in experiments was then numerically processed in order to present them in the form of graphs. Graphs showed that in most running conditions bigger |SRR| value resulted in higher coefficient of friction. However, there was one exception. When the contact was tested at lower load and at negative SRR values, growing of |SRR| reduced coefficient of friction. Additionally, the contact between polymer and steel showed lower coefficient of friction at higher load, compared to tests performed at lower load. These phenomena might indicate that there is increased formation of polymer transfer film on steel counterpart under higher load.
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