Nano-finishing of cylindrical hard steel tubes using rotational abrasive flow finishing (R-AFF) process

Abstract

Abrasive flow finishing (AFF) process is used to deburr, polish and radius surfaces and edges by flowing a semisolid viscoelastic abrasive medium over the surface to be finished. The AFF process is used in the industries especially in the case of finishing complex internal and external shapes. However, the AFF process is a time-consuming process due to its low finishing rate. Efforts are made by different researchers to improve its finishing rate. Rotational abrasive flow finishing (R-AFF) process is one of such processes where in complete workpiece tooling is externally rotated and the medium reciprocates with the help of hydraulic actuators to improve the finishing rate. In the present study, experiments are conducted on hard steel (AISI 4340) cylindrical tubes at different extrusion pressures, workpiece rotational speed, number of cycles and medium compositions for finding optimum conditions of the same for higher change in out of roundness (ΔOOR) and material removal (MR). In this study, soft styrene-butadiene- and silicone polymer-blended medium is used for finishing. Initially, these hard tubes are ground using internal grinding process. Because of grinding process, the workpiece possesses OOR of about 2.75 μm. Later, these workpieces are finished using R-AFF process and OOR improves to 1.69 μm (i.e. ≈39 % improvement). Overall, the results of R-AFF are encouraging and the experiments have shown that R-AFF has a very promising future for the industries in terms of better finishing.