Improvement of tribological properties of co-acting elements by oil pockets creation on sliding surfaces

Abstract

Sliding experiments were carried out using a block-on-ring friction machine. The tribosystem consists of the stationary block (counter-specimen) pressed at the required load P against the ring (specimen) rotating at the defined speed. The sliding was unidirectional. The block was a part of a bearing sleeve hardened EN-GJS 400-15 cast iron with a hardness value of 50 HRC. The ring samples, 35 mm in diameter, were made from hardened 42CrMo4 steel of hardness 32 HRC. Some variants of specimen surfaces were created by burnishing technique. Two kinds of experiments were done. Seizure tests were conducted at increasing pressure for sliding speeds in the range: 0.27–0.55 m/s. Wear resistance test was carried out under artificially increased dustiness conditions, too. It was found that surface texturing improved seizure resistance for the smallest sliding speed (0.27 m/s) comparing to untextured ground samples. The wear of steel rings with spherical dimples was smaller than of those having dimples of long drop shape for the pit-area ratio range of 7.5–20%.