Investigation on the chip formation concerning tool inclination angles in ball end milling of H13 die steel

Widespread application of ball end milling operation is an outstanding characteristic in the field of manufacturing of die and molds. Tool inclination angles, which could improve the cutting performance of ball end mill, are critical factor in the ball end milling process, and also chip formation is one of the most important phenomena in the machining process. Numerical simulation, geometric analysis, observation by optical microscope and scanning electron microscope, and energy-dispersive spectroscopy analysis were adopted to study the chip formation during ball end milling of H13 die steels involving tool inclination angles in this work. The theoretical uncut chip geometry and tool-work contact zone were analyzed by computer-aided modeling technology. Finite element modeling of chip formation process involving tool inclination angles was performed, and variations of the maximum chip temperature which could provide assistant understanding of practical chip formation were analyzed. This article also investigated the practical chip morphologies, chip color, and the cutting characteristics under different process conditions and tool inclination angles. The optical microscope and scanning electronic microscope were used to capture the micro-photos of the chips under different process parameters, and the chip color and chip morphologies were discussed together with the cutting characteristics with regard to various process parameters. Energy-dispersive spectroscopy analysis of the chip free surface and back surface was also carried out for some special tool inclination angles. Deep understanding of the chip formation in multi-axis milling process was enhanced, and the research work could provide support for the selection of process parameters to some extent.