Surfactant free enhancement to thermophysical and tribological performance of bio-degradable lubricant with nano-friction modifier for sustainable end milling of Incoloy 925

Abstract

An efficient method of lubrication and cooling for green machining is nanofluid minimum quantity lubrication (NMQL). Compared to other vegetable-based oils, coconut oil has the highest viscosity index, lubricity, and oxidative characteristics, making it a popular trending lubricant for decreasing friction. However, its performance at higher temperatures degrades owing to higher saponification value. In order to improve its performance, the solid nano-friction modifier (hBN) is dispersed in it, and the colloid is called a nanofluid. UV–Vis–NIR spectrophotometer, HR-TEM, and FTIR spectroscopy characterize nanofluid. The stability of nanofluid at 0.3 vol% of hBN has been observed to be the highest compared to other volume fractions. Compared to coconut oil, prepared nanofluid is superior in terms of increased thermal conductivity, thermal stability, and viscosity for all the tested temperature ranges. Nanofluid shows increased viscosity index (VI) by 20%, reduced contact angle by 45%, and lower coefficient of friction (COF) by 32% compared to coconut oil. Further performance of this modified biodegradable nanofluid under Minimum quantity lubrication (MQL) on end milling of Incoloy 925 has been studied. In order to compare the machining performance under different cutting environments, cutting temperature, cutting force, specific cutting energy, power consumption, carbon emission, chip morphology, surface topology/topography, and tool wear were evaluated. Finally, sustainability assessments for different cutting environments have been performed. Biodegradable oil-based NMQL-assisted machining has performed better than dry and MQL-assisted machining.