Abstract
Haynes-25 is a cobalt-based alloy resistant to oxidation and possesses high-temperature properties. Despite the excellent properties, the machinability of Haynes-25 is extremely difficult. Sustainable machining of this alloy is inevitable for producing earth-friendly products. Thus, researchers and scientists have been seeking alternative sustainable technologies to machine these alloys. In the present study, efforts are made to explore the machinability, energy consumption, and economic feasibility of a novel oils-on-water (OoW) lubrication approach mixed with cryogenic liquid nitrogen (LN). Twenty external turning experiments were performed under this novel cryogenic-LN oils-on-water (LNOoW) approach and compared with conventional machining approaches. Machining performance (temperature, cutting power and energy, tool wear and tool life, and surface quality) and economic aspects (production cost) were considered as response metrics. Column graphs are plotted for each metrics to compare the results. The results showed that the proposed LNOoW lubricooling approach reduced the cutting temperature and improved the surface quality of the workpiece significantly. Furthermore, less cutting power and electrical energy consumption were achieved in the proposed cooling/lubrication approach. The novel LNOoW approach also enabled an extension of about 97.56 to 111.11% of cutting tool life as compared to flood-assisted machining process. In addition, 11.76% of surface roughness and 38.725 yen cost reduction was obtained at the lowest level of feed rates. It was noted that better economic benefits could be obtained at the highest feed rate and the mid-range levels of cutting speeds. Furthermore, 50% economic benefits are achieved at medium cutting parameters in the LNOoW approach. Overall, the LNOoW approach out-performed in all the metrics. Therefore, the LNOoW approach has a high potential to replace the old cutting technologies. The present work can be used as fundamental guidelines for the machinist working in the metal processing industry to adopt the hybrid LNOoW approach successfully in the machining process.