Increased rolling strength and friction reduction for bearings and homokinetic joints due to innovative hard machining

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The fatigue life time and the friction conditions are limiting factors during the operation of bearing components. These factors are many influenced by the surface integrity properties residual stresses and surface topography within the contact area and the prevailed stresses. The goal of this application is to desgin and create an optimal surface integrity state for bearings and homokinetic joints by an innovative hard machining process. The necessary surface integrity will be induced by reliable and finacial processes. Due to analyzing roller bearings and homokinetic joints the tribologiy states full lubrication and mixed friction are considered in this application. In the first application periode the focus stays on the roller bearings. Due to the processes hard turning and deep rolling the necessary residual stresses and surface topography can be created, altough the processes have to be adjusted to each other. For a very low surface roughness, the deep rolling can cause a deterioation of the surface quality. A created model to calculate the lifetime of bearings can consider the preconditions due to residual stresses and shows an improvement of the lifetime. To analyse the effects for the mixed friction in homocinetic joints, the significant to affect the surface integrity due to process parameters for the milling will be determined at the end of this period. The following application will increase this knowledge. For the roller bearing a financial and reliable process combination of hard truning and deep rolling, turn-rolling, and its effects on the surface integrity will be analyzed. The created models for the full lubrication will be verfied in statitical lifetime tests of the bearings. For the homocinetic joints the influence of the milling process and cutting edge geomtry on the surface integrity, residual stresses and topography, are going to be examined. Finally the effect of the different topography an residual stress state will be analyzed in means of the tribology conditions and lifetime. The results will show, that the models for the full lubrication can be tranfered to the mixed friction area.