Experimental investigation into tool aging effect in ball end magnetorheological finishing

Abstract

Magnetorheological (MR) finishing is a smart finishing processes applied to a variety of applications. In the present work, an attempt has been made to improve the percentage reduction in surface roughness with sintered magnetic abrasives based MRP fluid on BEMRF tool. Sintered magnetic abrasives were developed by mixing of 20 vol% carbonyl iron powder (CIP) CS grade and 25 vol% SiC in ball mill then pellets of 5 g each have been made at 8 ton pressure. These pellets were allowed to sinter in tubular furnace at 1200 °C in the controlled atmosphere of argon. The sintered pellets were crushed in a ball mill to obtain sintered magnetic abrasives. The morphology and magnetizability of sintered magnetic abrasives have been studied with scanning electron microscope (SEM) and vibration sample magnetometer (VSM). MRP fluid was synthesized with 45 vol% sintered magnetic abrasives and 55 vol% base fluid. Experiments were conducted on mild steel work-piece for 30 min using BEMRF tool at given machining conditions. Percentage reduction in surface roughness (%ΔR_a) was calculated and compared with %ΔR_a obtained by finishing mild steel work-piece with unbonded magnetic abrasives based MRP fluid and found better results. The effect of rotation per minute (RPM) on %ΔR_a has been studied and found optimum by conducting the experiments at higher values of RPM keeping other machining conditions same. The experimental study shows that the sintered magnetic abrasives based MRP fluid in MR finishing may be used at higher rotational speeds without tool aging effect and impart a higher finishing force on the work-piece surface, improves finishing capability of the process.