Analysis of Heat Transfer Coefficient in Turning Process

Heat development during the metal machining process is a major challenging issue for the machinist. In the turning process, heat is distributed among chip, tool, workpiece, and cutting surrounding. This heat dissemination significantly influenced the complete cutting action. Further, heat transfer directly influenced the cutting attributes like wear growth rate, cutting life of the tool, surface finish, and workpiece dimensional precision achieved. In the current work, the stepwise procedure is deliberated to estimate the convection heat transfer coefficient for the workpiece into the surrounding and tool–workpiece interface into the surrounding. Further, the influence of input cutting terms (axial feed and cutting speed) onto the convection heat transfer coefficient is studied with the help of the main effect plot and surface plot. Highest heat transfer coefficient (h_c = 32.2 W/m² K) value (from workpiece into surrounding) is obtained at highest cutting speed (75 m/min) with the lowest feed (0.25 mm/rev) cutting conditions, while greatest heat transfer coefficient (h_in = 3.1 W/m² K) value (from the interface of tool–workpiece into surrounding) is noticed at a moderate speed (60 m/min) with axial feed (0.30 mm/rev) cutting conditions. Heat transfer coefficient (h_c) for workpiece into surrounding is improving with accelerating cutting speed, while it reduces sharply till 0.30 mm/rev of axial feed but further slowly increases. Heat transfer coefficient (h_in) for the interface of tool–workpiece into surrounding is retarding with axial feed, whereas it is sharply increasing up to 60 m/min of machining speed beyond this it is almost constant.