Shiva Tummala
2017 unpublished
Various approaches has been proposed in order to improve tribological behavior, some of which are lubrication, coating, and surface modification such as texturing, which is the center of attention of this work. Dimple Texture Forming is the proposed area of study. Dimple Texture Forming in friction pairs is one of the wear reduction techniques. In most of the contact mechanisms, the materials chosen for two contacting parts are different; the reason behind this is wear happens on both the parts
more » ... s on both the parts since they are of same material. For example, in case of shaft and bearing, it is difficult to replace the shaft since it is cost effective, whereas bearing can be replaced easily; so shaft is made of different material compared to bearing. But if we can use dimples texturing on any of the mating parts, same material can be used for both the contacting parts, and this is the main area of study in this work. By texturing the surface with Dimples, the value of surface roughness throughout the surface remains constant at peak; this eliminates the surface roughness variations on the surface of an un-textured surface, since it will be peak only at some places and varies throughout. In this work, different geometries of the Spherical and Elliptical Dimple Textures were formed using Laser Surface Texturing. The tribological performance of the sliding pair mainly depends on shape geometry and density of the patterned micro-texture features (dimples).The effect of these micro-dimples on friction properties were experimented by using Pin on Disc Tribometer ASTM G99 for a Brass disc mated with Brass pin (same material for both pin and disc). Concurrently, Un-textured surface frictional properties were also tested using Pin on Disc Tribometer ASTM G99. Compared to a smooth surface without texturing, some textured surfaces successfully indicated the Reduction of coefficient of Friction. Spherical dimples with 150 microns diameter and 75 micron depth provided the minimum coefficient of friction from the experiments. There was valid evidence proving that dimple shape and geometry was the optimum texturing solution to increase tribological properties. Results also indicted that optimum texture density might exist at which the surface shows the best Friction and Wear behaviour. INTRODUCTION Friction is involved in thousands of applications in our daily lives. In some applications high friction is desirable, as in vehicles' tires on the roadways, brakes, clutches, and frictional power transmission systems. In other applications, friction reduction is a constant demand which reflects on energy efficiency, component durability, and system reliability. For example, the energy loss due to friction in automobiles is estimated to be 40% of the total energy generated by the internal combustion engine. In all cases, understanding the mechanisms involved in friction and the means to control it are necessary. Various approaches have been engaged in order to improve tribological behavior, some of which are lubrication, coating, and surface modification such as texturing, which is the center of attention of this work. Lubrication, whether hydrodynamic, boundary, or mixed is one solution to control friction, however, lubrication in some operating conditions is not applicable. In addition, surface coating is another effective means of reducing friction. High strength and low friction coating materials have been employed in a wide range of applications, yet surface coating sometimes faces the challenges of de-bonding and fractures of the coating layer, which may result in more catastrophic results. Therefore, researchers have been searching for a more reliable approach that can control friction in all operating conditions. Three decades ago, attention was drawn to surface patterning, or surface