For the operation of roller bearings in the mixed or boundary friction regime, sufficient protection against wear is required for an adequate lifetime. Suitable additives, in this case extreme pressure (EP) und anti-wear (AW) additives, feature these requirements when applied to the lubricant. These additives form a tribological boundary layer on the surface of the contacting rolling bearing elements thereby inhibiting direct steel-steel contact and minimizing abrasive and adhesive wear. Therefore, these layers are also called anti-wear layers.
With regard to resource conservation, the additive concentration in lubricants is continuously reduced. This may lead to an increased risk of adhesive and abrasive wear in rolling bearings operated in the mixed and boundary friction regime due to impossible formation of a protective boundary layer. The lifetime of the rolling bearings is limited as a result. Previous tests with cylindrical roller thrust bearings in an FE8 test rig have shown that the ability of forming a protective boundary layer depends on the additive amount in the area of the tribological contact. This amount is influenced by both, the additive concentration in the oil and the operating conditions of the bearing.
To overcome limitations by restricted additive concentration and defined operating conditions, laser surface texturing can be used to improve the additive amount artificially. Mircodents on the surface can create oil reservoirs. This contribution will show the benefits of the surface texturing on the formation of anti-wear layers and the possibility to inhibit abrasive and adhesive wear. Preliminary tests have shown that this surface treatment can reduce wear by 80% and furthermore, friction is decreased by 10%.