Effect of surface texture positioning in grease lubricated contacts

It is generally established that use of well-designed artificially enhanced surfaces in certain lubricated conjunctions can potentially improve the tribological performance under specific operating conditions. However, there is a considerable lack of understanding of the effect of texture features, which are not exposed to conditions in the contact footprint, to the overall tribological performance. Three discs have been manufactured, one without texture features and two with texture features but in different locations with respect to contact footprint. The discs were tested in a ball on disc tribometer under representative contact conditions from practical application cases as such contacts can experience a multitude of regimes of lubrication during the operation. The contacts were lubricated by grease. Texture features placed directly beneath the contact were shown to provide a negative effect by increasing the measured coefficient of friction relative to the untextured disc. Textures placed outside, but at very close proximity of the contact footprint track on the disc, were shown to reduce the measured friction coefficient and wear simultaneously.