Optimization of Cutting Parameters for Surface Roughness under MQL, using Al2O3 Nanolubricant, during Turning of Inconel 718

Abstract

Inconel 718 is a nickel-based alloy commonly used due to its excellent mechanical properties at high temperatures and its elevated corrosion resistance. This material however is difficult to machine due to the high temperature generated during machining, which requires efficient lubrication system. Minimum quantity lubrication (MQL) technique is a more efficient and a more environmentally friendly alternative to conventional flooding lubrication technique. The efficiency and efficacy of this lubrication technique can be further enhanced by adding nano particles and surfactant into the base lubricant. There are currently limited number of studies on the application of minimum quantity lubrication (MQL) technique using nanolubricant with added surfactant in the machining of hard-to-machine materials such as Inconel 718. Consequently, this paper aims to optimize the cutting parameters for surface roughness under minimum quantity lubrication (MQL) condition using surfactant-added Al2O3 nanolubricant during the turning of Inconel 718. The effects of cutting speed, depth of cut and feed rate and their two-way interactions on surface roughness are investigated on the basis of the standard Taguchi's L9 orthogonal array (OA) design of experiment and the results are assessed using analysis of variance (ANOVA) and signal to noise (S/N) ratio methods to determine the optimal cutting parameter settings as well as the level of significance of the cutting parameters. The optimal surface finish can be observed at the cutting speed of 70 m/min, depth of cut of 0.05 mm and feed rate of 0.05 mm/rev with feed rate being the most significant factor to affect surface finish. Through this study, the application of minimum quantity lubrication (MQL) technique using surfactant-added Al2O3 nanolubricant, has been shown to produce desirable surface finish quality on Inconel 718 with additional economic and ecological benefits.