Sustainable High-Speed Hard Machining of AISI 4340 Steel Under Dry Environment

To curtail the uses of cutting fluid, the preference for a dry machining environment has been a continuous motivation for researchers using coated carbide tools. High strength AISI 4340 low alloy steel is the most promising and potential material with wide applications in couplings, main shafts, spindles, and gears for power transmission. Environmentally friendly machining, such as high-speed turning, has focused a lot of attention on the machining industry. However, inappropriate selection of the input cutting variables may cause augmented work surface roughness, excessive tool wear, and cutting temperature. Keeping this in view, it is necessary to analyze some key machinability features during the turning of hardened AISI 4340 steel. The present research is to investigate how (TiN/TiCN/Al 2 O 3 ) Chemical Vapor Deposition carbide-coated inserts perform throughout the hard turning process on AISI 4340 steel. The vital evaluated parameters are average surface roughness, cutting temperature, flank wear, and chip morphology. It was observed that one of the governing factors that influence surface roughness is feed rate. To obtain the optimum level of input parameters, the Taguchi coupled with TOPSIS was implemented. The results summarized that abrasions, adhesion, built-up-edge formation, chipping off were observed as key accounts in the direction of tool wear. Further, to better understand tool wear and generated chip surface characteristics, SEM and EDS analyses were performed. Results demonstrated that saw tooth chips are formed in dry hard orthogonal turning process. The induced optimal cutting parameter setting (d 1 -f 1 -v 1 ) improves the machining performance.