Analyses of robotic milling vibration based on the tool-workpiece engagement process

Robotic milling is a promising technique for machining large components. However, its stability is affected by the milling vibrations. Existing studies have ignored the complex tool–workpiece engagement caused by the low stiffness of the robot. In this study, the robotic milling vibrations were analyzed to avoid unstable milling. Moreover, the existing milling stability criterion must be modified according to the vibration analysis to adapt to robotic milling. To address these issues, the tool–workpiece engagement was analyzed and simulated to elucidate the robotic milling process and detect the milling stability. First, the dynamic model of a robotic milling system and a cutting force model were introduced to simulate the robotic milling process. These models were combined by using the strategies for processing the tool nose trajectory. By considering the complex tool–workpiece engagement, the tool nose trajectory processing strategies were updated for robotic milling. Based on the engagement process, the robotic milling process was analyzed to explain the formation of distinct vibration components in robotic milling. This analysis enabled the modification of the existing stability criteria to suit the robotic milling process. The analyzed tool–workpiece engagement and robotic milling vibrations were validated through robotic milling simulation and experiments. The modified stability criterion was employed to detect the robotic milling stability.