Determining the effect of tool posture on cutting force in a turn milling process using an analytical prediction model

Turn milling is a key technique that can be used to achieve high-efficiency machining and improve life of tools used for difficult-to-cut materials because intermittent cutting with multiple cutting edges can suppress a rise in temperature compared with conventional turning. However, the contact condition between the rotary tool and the cylindrical workpiece varies significantly depending on the tool posture, which is defined by the tool axis inclination angles against the workpiece: namely, lead and tilt angles. Thus, clarifying the effect of the lead and tilt angles on cutting forces in turn milling is essential for determining the optimal tool posture. In this paper, we propose a simulation model to predict the cutting force for 5-axis turn milling considering the contact behavior between the tool and workpiece depending on the tool posture. The workpiece is modeled as a point cloud and any points that interfere with the tool volume are removed when the tool edge passes the surface of the workpiece. We examined the simulated cutting forces using a radius end mill as a linear function of the uncut chip thickness and found that the predicted cutting forces were in agreement with the experimental results for several combinations of tool postures and feed rates. We also clarified that the tool posture significantly affects the maximum cutting force, which varies even if the material removal rate is maintained at a constant value in the turn milling process.