Hard Machining of Inconel 690 Using Minimum Quantity Nanoparticle-Enriched Vegetable Oils: A Sustainable Approach

In response to the growing demand for sustainable manufacturing solutions, this research focuses on developing environmentally friendly lubricants designed to reduce friction at the tool–workpiece interface. The study investigates the performance of vegetable oil-based nanofluids, specifically using soybean oil as the base fluid enriched with alumina and silica nanoparticles at concentrations ranging from 0% to 1.4%. Spectroscopic characterization was employed to determine the most effective nanoparticle concentration. Subsequently, hard machining experiments on Inconel 690 were carried out under four lubrication strategies: dry cutting, compressed air, soybean oil with 0.8% alumina nanoparticles, and soybean oil with 0.8% silica nanoparticles. Among these, the alumina-based nanofluid demonstrated superior performance, achieving reductions of 43.70% in surface roughness, 22.70% in cutting force, 20.03% in temperature, and 45.65% in tool wear relative to dry machining conditions. To further optimize the process, a Taguchi experimental design comprising 27 trials was applied under the optimal lubrication condition. A genetic algorithm was then used to fine-tune machining parameters, and experimental validation revealed a strong correlation between predicted and actual outcomes, with a mean error of only 3.04%. Overall, the findings highlight the effectiveness of nanoparticle-enhanced bio-lubricants in improving machining performance, extending tool life, and supporting environmentally responsible manufacturing practices.