Effect of lubricant starvation on the tribo-dynamic behavior of linear roller guideway

This paper presents an experimentally validated numerical approach linear roller guideways considering coupled vertical and horizontal (feed) motions and taking into account lubricant starvation. The inlet starvation is considered by incorporating potential flow method. Results show that starvation has pronounced effect on the lubricant film thickness, friction and applied load on contact by up to 32%. Localised pressure values may vary by up to 100%. The severity of starvation effect is frequency dependent. It is also revealed that the starvation effect can be controlled by the amount of preload on linear guideway

Coupled tribo-dynamic modelling of linear guideways for high precision machining application

Linear guideways play a crucial role in determining precision of machine tools. Understanding their dynamic response is essential for objectively controlling their behavior and performance in operation. Due to highly loaded lubricated contacts, mixed-elastohydrodynamic regime is dominant. The mixed-elastohydrodynamic film maintains the coupling between horizontal degree of freedom (feed velocity) and vertical degree of freedom (loading direction). This paper presents a novel tribo-dynamic solution for linear guideways, taking in to account the lubricant effects and coupling between horizontal and vertical degrees of freedom. An analytical tribology model is used implicitly within the dynamic model. For in-depth tribological quantities including pressure and film thickness distribution, an explicit full numerical solution for mixed-elastohydrodynamic is utilized. Results show that the coupled solution of vertical and horizontal degrees of freedom taking in to account lubricated contacts is essential. It is shown that at moderate and light loads, the effect of this coupling and presence of lubricant is more pronounced

Effects of diamond-like carbon and tungsten-carbide carbon coatings on tribological performance of cam–tappet conjunction

Cam–tappet contacts are responsible for ~7.5% of the internal combustion engine’s (ICE) total frictional losses. The application of coatings can improve the tribological performance of these contacts. In this paper, the application of a WC-C coating as a novel approach for cam–tappets in comparison with DLC coating is investigated. The tribological performance of the coated contacts are evaluated by a novel model comprising combined implicit analytical and explicit numerical methods. This model considers the coupled tribo-dynamic behaviour whilst obtaining detailed tribological performance. The combined approach provides a computationally efficient platform. The results show that application of DLC or WC-C can improve the film thickness value by up to 41%. They can improve boundary friction, whilst increasing the viscous friction