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

Abstract

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.

Geometrical Modeling of Tool-Workpiece Contact Zone and Chip Formation in Finish Ball End Milling Process with Tool Inclination Angles

“…Cosmas [5] focused on the geometrical modeling of the undeformed chip in ball nose end milling. Chen et al [6] investigated the chip formation characteristics in multi-axis ball end milling process, and the geometrical modeling and experimental measure method were both adopted. Although some works concentrated on modeling of the chip formation for ball end milling process considering relative tool-workpiece postures, further systematic and intuitional analysis of the effects of the tool inclination angles on the tool-work contact zone and chip formation is needed.…”

“…lead angle is introduced by rotating the tool axis about the cross-feed direction. The positive lead angle is defined as rotating the tool axis in counterclockwise direction seeing from the positive direction of x-axis (cross-feed), while the negative lead angle is the inverse intersection angle [6].…”