Predicting the Effects of Tool Nose Radius and Lead Angle on Hard Turning Process Using 3D Finite Element Method

Finite element method (FEM) has been qualified as an excellent method to analyze machining processes. Many researchers commonly adopt an orthogonal FE model to simulate hard turning process without considering the effect of tool nose radius and/or lead angle. However, the PCBN cutting tools usually possess a nose radius of 0.4mm to 0.8mm, which equals to the magnitude of cutting depth/feed in hard turning. To explore the effect of tool nose radius and rake angle on hard turning AISI 52100 steel process, an explicit dynamic thermo-mechanical three-dimensional (3D) FEM is developed. The model considers tool nose radius as 0.4mm and 0.8mm, respectively with a tool lead angle of 0° and 7°. The model successfully simulates 3D saw-tooth chip morphology generated by periodic adiabatic shear and demonstrates the continuous and saw-tooth chip morphology, chip characteristic line and the material flow direction between the chip-tool interfaces. The predicted chip morphology, cutting temperature, plastic strain distribution and cutting forces agrees well with the experimental data. The oblique cutting process simulation reveals that larger lead angle enables work material deformation more severely, the maximum temperature on the chip-tool interface reaches 1289°, close to the measured average temperature of 1100°; the predicted average tangential force is 150N, with 7% difference from the experimental data. When the cutting tool nose radius increases to 0.8mm, the chip’s temperature and strain becomes relatively higher, and average tangential force increases 10N. This paper also discusses the disagreement between the predicted and experimental cutting force.