INVESTIGATIONS ON ULTRA-SONIC ASSISTED AFM

Abstract

Abrasive flow machining (AFM) is a non-traditional machining technique, which is one of the most important methods for finishing of components at ultraprecision level. The variants of abrasive flow machining such as Centrifugal Force Assisted Abrasive Flow Machining (CFAAFM), Magnetorheological Abrasive Flow Finishing (MRAFF) etc. have shown satisfactory results as compared to AFM in terms of improved material removal rate and surface finish.- Spiral flow assisted abrasive flow machining, a new variant of AFM, is a method applied for high speed revolution of abrasive media and circulating it around the workpiece during the process. Ultra-Sonic assisted abrasive flow machining (UAAFM), another newly found variant of AFM and developed at IIT Roorkee, has shown better results in comparison to spiral flow assisted AFM. The ultra-sonic assisted abrasive flow machining is the combination of ultrasonic machining and abrasive flow machining which will enhance the interaction of abrasive particles with the workpiece surface during machining operation, and improves the overall performance of the AFM process. The vibration was given to the workpiece in direction perpendicular to the longitudinal direction with the help of the actuator, mechanically coupled to the machine. The vibration to the actuator was given through KC DC N15 (Kinetic Ceramics Ltd.) which is further attached to amplifier. The feed to KC DC N15 was given by a control. The frequency limit of the device is 5-20 kHz. The parameters that were varied during the experiments are vibration frequency, extrusion pressure, media flow rate and processing time. The results obtained after machining of EN-8(Stainless Steel) by Ultra-Sonic assisted AFM were found better than the hybrid AFM processes developed earlier. The percent improvement in surface finish obtained was 50.94% and maximum material removal rate obtained was 5.33 mg at 15 kgf/cm2 after 4 minutes of processing time of EN-8. The minimum surface roughness (Ra) obtained after UAAFM is 617 nm at 15 kgf/cmz. In conclusion, it can be firmly stated that the UAAFM is a hybrid AFM process which resulted in better surface finish and higher material removal with respect to basic AFM.