Waldemar Koszela

Tribological behaviours of textured surfaces under conformal and non-conformal starved lubricated contact conditions

Wear tests were carried out using a pin-on-disc tester. The sliding friction experiments were made using textured and untextured discs of 50 HRC hardness, under starved lubricated conditions in unidirectional sliding. Two batches of tests were done. The special construction was made to obtain conformal contact in the first type of tests. In the second test type in non-conformal initial point contact condition, a steel disc was put in contact with a ball from bearing steel of 3.175 mm radius. Two kinds of textured discs were tested; the oil pockets were positioned in spiral and radial arrays the number of oil pockets within friction track also varied. It was found that in conformal contact conditions the presence of dimples resulted in considerable decrease of the friction force compared to untextured samples. Surface texturing caused transition from point to conformal contact during test, which resulted in decrease of friction force but increase of wear of balls. The tribological behaviour of assembly with spiral dimples layout was better than that with radial array of oil pockets.

Effect of Surface Texturing on the Steady-State Properties and Dynamic Coefficients of a Plain Journal Bearing: Experimental Study

The last decade has seen a significant and increased interest in surface texturing technologies esulting in improving the overall tribological properties of mechanical components. Several techniques could be used to modify the surface topography with laser surface texturing becoming most popular recently. In this investigation, rig experiments have been performed on plain and textured-surface journal bearings with an aspect ratio of 1.1 under a variety of loads and speeds. Percussive burnishing (embossing) was used to create the dimples on the internal surfaces of the test bearings. The dimples have a spherical shape with a diameter of 1 mm and a depth of 60 micrometers. Pit-area ratio was in the range 5–20% of the total bearings surfaces. The effects of surface-texturing and dimple density on the bearing steady-state characteristics and dynamic coefficients are analyzed and discussed in this paper.Copyright