A comparative experiment study of effect of various vegetable oils with MQL system during the machining of Ti alloys

Purpose A large amount of lubricant used in machining causes environmental, disposal, health and cost issues, impacting sustainable machining. This study aims to compare eco-friendly vegetable oils with conventional mineral oils as lubricants during titanium machining, using specific machining conditions and the minimum quantity lubrication (MQL) technique to evaluate the impact on surface roughness and cutting forces. Design/methodology/approach The evaluation of the impact of various machining parameters and vegetable oil lubrication on surface roughness and cutting forces is the focus of this study. The experimental methodology incorporated the MQL technique and turning operations on a titanium alloy. The viability of vegetable oils as an environmentally responsible alternative to conventional cutting fluids is simultaneously assessed in the pursuit of sustainable machining practices. In the experimental design, machining parameters, such as cutting velocity, depth of cut, feed rate, oil pressure and nozzle inclination angle, were systematically varied, while the lubricant flow rate was maintained constant throughout all trials. Findings Experimental evidence indicates that MQL using vegetable oil-based lubricants yields favorable outcomes, demonstrating a viable alternative to conventional mineral oils. Specifically, cutting force and surface roughness were significantly reduced, approximately by 18% and 20%, respectively, across the investigated machining parameters. Furthermore, depth of cut was identified as the predominant factor influencing both cutting force and surface roughness response variables. Originality/value A comparative investigation of vegetable oils such as palm oil and sunflower oil with synthetic oil under identical MQL conditions. Evaluation of their performance under practically relevant low-speed machining parameters, aligning with real-world applications. Focused analysis linking the physicochemical properties of the oils and machining parameters to measurable machining outcomes such as cutting force, tool wear and surface finish. Providing experimental insight into the effectiveness of palm oil as a sustainable alternative to synthetic oils in the precision machining of Ti alloys, which is of industrial relevance, particularly for aerospace and biomedical sectors. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-03-2025-0103/