Magnetic abrasive finishing of hardened AISI 52100 steel

Surface finish has a vital influence on functional properties such as wear resistance and power loss due to friction on most of the engineering components. Magnetic abrasive finishing (MAF) is one of the advanced finishing process in which a surface is finished by removing the material in the form of microchips by abrasive particles in the presence of magnetic field in the finishing zone. In this study an electromagnet with four poles has been used which was found to give better performance in terms of achieving surface quality in lesser processing time. Voltage, mesh number, revolutions per minute (rpm) of electromagnet, and percentage weight of abrasives have been identified as important process parameters affecting surface roughness. The experiments were planned using response surface methodology and percentage change in surface roughness (Delta Ra) was considered as response. Analysis of experimental data showed that percentage change in surface roughness (Delta Ra) was highly influenced by mesh number followed by percentage weight of abrasives, rpm of electromagnet, and voltage. In this study, the least surface roughness value obtained was as low as 51 nm in 120 s processing time on a hardened AISI 52100 steel workpiece of 61 HRC hardness. In order to study the surface texture produced and to identify finishing mechanism, scanning electron microscopy and atomic force microscopy were also conducted. Shearing and brittle fracture of small portion of peaks of grounded workpiece have been found to be finishing mechanisms during MAF of AISI 52100 steel.