Research Projects

Performance of rolling element bearing depends upon the surface properties and surface texture of ball/roller and raceway. Manufacturing process of ball/roller and raceway significantly affects the surface properties and texture of it. Effect of manufacturing processes on friction coefficient in mixed lubrication regime, and finally bearing performance and life will be examined in the current project.Machine components fail due to asperity-to-asperity contacts in tribological contacts such as gears, bearings, cams, sliders, surfaces of blade root with discs. These kinds of components are widely prevalent in wind turbines, off-highway vehicles, mineral mining, paper industry, cement industry. The friction generated between mating components leads to failures, wear out and heat generation. It hinders the motion and expends more energy. For electric vehicles reduction in energy loss due to friction will lead to better management of charging system. This proposal aims to study rolling element bearing friction for different surface topography generated during manufacturing processes of tribological components. Understanding of these surfaces-isotropic, anisotropic, Gaussian and non-Gaussian has to be done to understand the nature of the asperity interaction. This will be done experimentally and at analytical level. Various models for analysis of the frictional torque will be compared and validated with experimental results in rolling element bearing. Analytical study will be modeling surface topography at stochastic level and then friction due to mixed lubrication. The subscale experiments will be carried out for rolling/sliding, pure sliding and oscillatory types of motion. Mainly, two roller machine and multi-functional tribometer will be used for experimental analysis. The validated models will be applied to actual bearing tests. Experiments will be done for various operating conditions to demonstrate the effect of load, effect of different surface topography, effect of oil-in-temperature, and effect of slide-to-roll ratio (SRR) on friction coefficient. For characterization of worn surfaces, optical profiler, scanning electron microscopy (SEM), and micro-hardness tester will be used. This proposal aims to study change in surface topography with operational cycles, not just designing the surface topography of tribological components but also how the surface topography evolves and how the surface failure will result in expensive components failure. This fundamental understanding of asperity interaction at micro-level and surface failure mechanism at macrolevel will be addressed to develop solutions for preventing failures. Solutions such as performance of hard coating (TiN, DLC)) or soft coating (MoS2, Graphite, Silver) will be analyzed in the mixed lubrication region. Alteration of friction coefficient, coating surface and cracking of coating will be experimentally studied to assess the actual bearing performance in the mixed lubrication region.

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Achievements after six months - SURFACE TOPOGRAPHY STATISTICAL MODELLING IN 3D 1. In this model, an attempt is made to simulate anisotropic surfaces through use of topography parameters (three-dimensional (3D) surface parameters). First, 3D anisotropic random Gaussian rough surface is generated numerically with fast Fourier transform (FFT).

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National Bearing Company, Jaipur