Tool-chip friction in machining with a large negative rake angle tool

A fundamental and quantitative analysis of the tool-chip friction helps to better understand the mechanism of chip formation and other complex phenomena in machining with a large negative rake angle tool. Built upon Lee and Shafferʹs model, this paper presents an analytical slip-line approach to investigate how the negative tool rake angle and the cutting speed affect the tool-chip friction, and how the tool-chip friction further affects machining performances, such as the ratio of the cutting force to the thrust force, the chip thickness ratio, the geometry of the shear zone, and the geometry of the stagnation zone of material flow adjacent to the tool rake face. Published experimental data covering a wide range of negative tool rake angles and cutting speeds are employed to validate the analytical model. The predicted force ratio and chip thickness ratio are in good agreement with the experimental data. Different effects resulting from the positive and negative rake angles on the tool-chip friction are compared and analyzed.