Electrical discharge turning by assistance of external magnetic field, part II: Study of surface integrity

Surface integrity as one of the main outcomes of hybrid machining process has dominant effect on the life time of engineering material. In this work, surface integrity of the AISI D2 steel grooves produced by electrical discharge turning (EDT) process was studied through experimental investigation. Here, for first time magnetic force has been integrated with EDT process to find how it influences the surface properties such as surface roughness, thickness of recast layer as well as surface hardness. Series of experiments based on Taguchi experimental design have been carried out taken into account magnetic flux density, discharge current, pulse on time and workpiece rotational speed as main inputs. Statistical optimization using grey relational analysis (GRA) was performed to understand how the hybrid machining parameter should be selected regarding minimum surface roughness and recast layer thickness as well as maximum hardness. Results indicated that magnetic flux density as well as work rotational speed have great impact in determining the surface integrity of machined grooves. Also, it is found that 0.4 T magnetic flux density, 5 A discharge current, 1000 μs pulse on time and 250 RPM work rotational speed is an optimal parameter setting that leads to maximization of hardness as well as minimization of surface roughness and recast layer thickness. © 2020 The Authors