Investigating the Friction Behavior of Turn-Milled High Friction Surface Microstructures under Different Tribological Influence Factors

Abstract

The coefficient of friction (COF) is an important parameter for mechanical engineers to consider when designing frictional connections. Previous work has shown that a surface microstructuring of the harder friction partner leads to a significant increase in the COF. However, the impact of the changes in the tribological system on the COF are not known in detail. In this study, the tribological influence factors such as the nominal surface pressure, the material pairing, lubrication, and the surface properties of the counterbody are investigated. Microstructuring is applied by turn-milling of an annular contact surface of cylindrical specimens. A torsional test bench is used to measure the torque depending on the displacement of the two specimens, thus enabling the determination of the COF. All tests with the microstructured specimens result in higher COF than the reference test with unstructured samples. The manufacturing process of the counterbody surface, the nominal surface pressure, and the materials in contact have a significant influence on the COF. While lubrication reduces friction in the case of unstructured specimens, the COF does not change significantly for microstructured samples. This proves that the deformative friction component dominates over the adhesive. Microstructuring the harder friction partner increases the transmittable torque in frictional connections and reduces the sensitivity towards possible contamination with lubricants.