Study on surface integrity and material removal mechanism in eco-friendly grinding of Inconel 718 using numerical and experimental investigations

Knowledge of material removal behavior and generated surface characteristics are crucial to improve grinding performance. A finite element model was developed using a single grit approach with the consideration of uncut chip thick variations along the grain path. It was found that the increase in cutting speed and the decrease in rake angle led to the generation of discontinuous chips in adiabatic shearing conditions. Besides, the larger shear stresses induced by friction in the grain-chip interface contributed to the formation of chips with larger discontinuities. The enlargement of subsurface damage (SSD) depth by 23.86% and 129.42% was caused by the increase in grain edge radius from 0.5 to 2.5 mu m and the rise in maximum uncut chip thickness from 0.5 to 1.5 mu m, respectively. However, the SSD depth firstly decreased, and then increased with the approach to more negative rake angles and larger cutting speeds. A multi-response optimization based on analysis of variance (ANOVA) and SSD predictive model calculated the optimum combination of influential parameters as maximum uncut chip thickness of 0.719 mu m, cutting speed of 80 m/s, cutting edge radius of 0.5 mu m, and rake angle of - 30 degrees. This led to the minimum SSD depth of 0.406 mu m and the maximum removal rate of 57.493 mm(3)/mm s. The experimental results confirmed the positive contribution of an eco-friendly nanofluid minimum quantity lubrication (NMQL), containing graphene nanoplatelets with 0.3 wt% concentration within the green nanofluid, to the significant improvement of surface roughness (by 41.09%, relative to dry grinding) and morphology.

Automated summary

Understanding the material removal behavior and surface characteristics is crucial for improving grinding performance. A finite element model with consideration of uncut chip thickness variations along the grain path was developed to study the effects of cutting speed, rake angle, and grain-chip interface on chip formation and subsurface damage. Multi-response optimization identified the optimum combination of parameters for minimum SSD depth and maximum removal rate. Experimental results confirmed the positive impact of eco-friendly nanofluid minimum quantity lubrication on surface roughness and morphology improvement.