Investigation of Surface Texture Generated by Friction Drilling on Al2024-T6

Abstract

Friction drilling is a nontraditional hole-making process in which, a rotating conical tool uses the heat generated by friction to soften and penetrate a thin workpiece and create a bushing without generating chips. During friction drilling most of the frictional heat is retained in the tool-workpiece interface. The effect of frictional heating is relatively prominent; this causes excessive temperatures in the workpiece and results in undesired material damage and improper bushing formation. To overcome these issues, this study investigates the surface texture generated from friction drilling process to characterize the behaviour of friction drilling on Al2024-T6 material. The surface roughness and integrity are of prime importance for any machined components in terms of aesthetics, tribological considerations, corrosion resistance, subsequent processing advantages, fatigue life improvement as well as precision fit of critical mating surfaces. In this study, in addition to the surface roughness measurement, optical microcopy and Scanning Electron Microscopy (SEM) have been carried out to gain insight into the friction drilled surface. Obtained results from the microstructures depict that the development of the microstructures are affected by the magnitude of the friction forces and the heat produced during the friction drilling process. It is also found that from the micrographs there is no direct micro-structural evidence for melting of work-material in friction drilling.