A comprehensive assessment of minimum quantity lubrication machining from quality, production, and sustainability perspectives

The article presents minimum quantity lubrication (MQL) machining of Ti-6Al-4 V in a collective framework of multiple objectives - quality (surface roughness), environmental friendliness (specific cutting energy, tool wear, and oil consumption), and production (material removal rate and tool wear). In one of the first of its kind, the proposed approach uses cutting fluid parameters (oil quantity in the oil+air mixture, air pressure, and proportion of oil at the rake and flank face) along with machining parameters in multi-objective meta-heuristic optimization. The investigation reveals that the three objectives are distinct functions of process inputs. Thus, focus on one of the objectives - quality, production, and environmental aspects - hampers the others. A reasonable balance between the three aspects can be achieved through simultaneous optimization. Precise control over cutting fluid parameters, especially the oil proportion at rake and flank face, is a major factor that helps in improving environmental friendliness and productivity. The findings of the investigation will be useful for preparing a guideline for simultaneous selection of machining and cutting fluid parameters for economic and environmental viable manufacture of quality products.