Effect of Abrasive Medium Ingredients on Finishing of Al Alloy and Al Alloy/SiC Metal Matrix Composites Using Rotational Abrasive Flow Finishing

摘要

Al alloy/SiC composites possess better mechanical and physical properties thus finding applications in automotive, sports, and aerospace. In some cases, these components require nanolevel finished surface. But, traditional abrasive finishing processes are labor intensive, time consuming and confined to only simple geometries. Abrasive flow finishing (AFF) is one of the advanced finishing processes that can be used to finish complex surfaces by flowing polymer based abrasive medium but its finishing rate is low. In the present work, Rotational-AFF (R-AFF) process is developed where in workpiece rotates about its axis. This rotation provides the dynamic motion (additional force and velocity components) to the workpiece. By cumulative effect of workpiece rotation and medium reciprocation, the active abrasive particles try to abrade the workpiece in a helical path. Thus, finishing length and finishing rate both increase. In AFF process, because of more finishing time medium undergoes chemical change or degradation (loses its viscosity) because of continuous shearing and rise in temperature. Therefore the effect of medium shear viscosity variation with the temperature is studied to understand how the viscosity reduces with the temperature. Later complete experiments are conducted on R-AFF process by varying plasticizer to polymer volume ratio and polymer to abrasive ratio. The finishing from micron surface topography to nanosurface topography is studied using atomic force microscopy.