Enhancing hard parting off performance on AISI 304: A comparative study of conventional flood cooling and eco-friendly vegetable oil-based sustainable MQL

Machining operations are essential for producing precision components in aerospace, biomedical, and other advanced industries. This study addresses the notable research gap by focusing on the parting off operation of AISI 304 stainless steel, a process that has been largely overlooked compared to the widely studied turning operation. The machinability of this difficult-to-cut material was evaluated under dry cutting, conventional (mineral oil), and minimum quantity lubrication (MQL, vegetable oil-based) conditions. The dynamic viscosity and thermal conductivity of the cutting fluids were thoroughly analyzed both at room temperature and elevated temperatures simulating actual machining conditions, providing a comprehensive thermo-rheological characterization. Experiments were conducted at various feed rates (0.01–0.03 mm/rev) and cutting speeds (20 and 30 m/min). MQL and conventional cooling significantly improved performance metrics compared to dry cutting: surface roughness decreased by 64 % and 88 %, reaching 0.829 μm and 0.279 μm, respectively; cutting temperatures were reduced by 54 % and 62 %; and flank wear diminished by 71 % and 74 % under MQL and conventional methods, respectively. Real-time temperature monitoring and graphical recording demonstrated the effectiveness of the environmentally friendly and economical MQL system even in the challenging geometry of the parting off operation. The optimal results were obtained at a feed rate of 0.01 mm/rev and cutting speed of 30 m/min using MQL, where the cutting zone temperature and tool wear were significantly reduced, and the surface quality of the machined part was markedly improved, leading to a sustainable manufacturing process. This clearly establishes that vegetable oil-based MQL is a superior, eco-friendly, and cost-effective alternative to conventional cooling methods, even under demanding geometric conditions.