Cutting Forces Impact on the Spindle Path during Robotic Milling

Offline programming is a critical step in the implementation of various robotic tasks such as pick-and-place, welding, cutting, and milling. This paper describes a simulation study that analyses the accuracy of the robot's path tracking, during tasks that require the robot tool to interact with the environment, while considering the current operating conditions. To accurately determine the actual position of the Tool Center Point (TCP) and the associated orientation of the end effector, the study will first establish a robot model that takes into account the elasto-static behavior during the milling process that generates significant contact forces on the end effector. Then, an offline simulation tool is developed within the SolidWorks® CAD environment. The analysis of simulation results from multiple scenarios revealed that the tool/material contact forces were the main source of the robot's deviation from its nominal trajectories. Moreover, the range of positioning errors varies according to the architecture of the robot and the workpiece emplacement. Depending on the working conditions, the tool deflection ranges from 0.1 mm to 0.75 mm in the or cutting directions and increases as one moves away from the reference frame, while the Cartesian orientation deviation is negligible (less than 1°).