Application of eco-friendly lubricants in sustainable grinding of die steel

In recent years, increasing demand for biodegradable lubricants has been observed in precision machining owing to ISO 14000, which draws more attention toward the operator's health and environmental issues. In this context, vegetable oils are adopted as eco-friendly lubricants in sustainable lubrication techniques such as Small Quantity Lubrication (SQL). The grinding performance and surface integrity of AISI H13 die steel may also be improved via SQL. The present study aims at revealing the best lubricant for work material by comparing the lubricating characteristic of vegetable oils like castor, groundnut, sunflower, and soybean. The lubrication characteristics were studied in terms of force ratio, surface roughness, surface topography, microchip morphology, and wettability. Experiential results revealed that castor oil exhibited superior lubricating performance, including the lowest force ratio and surface roughness (R-alpha : 0.147 mu m and R-z : 1.122 mm), and outstanding surface quality. Furthermore, the wide bearing area (BC) curve and a higher BC ratio (81.76%) indicated the development of an excellent antifriction ground surface in the case of castor oil. The spherical and burnt chips were observed at an infeed of 32 mu m in the case of soybean oil. The viscosity of the lubricant significantly influenced the wettability. The lower viscous soybean oil promoted better lubricant wettability in the machining zone.