Robotic machining of aluminum alloy: evaluation of performance and part accuracy

Abstract: The automated machining is typically performed by CNC (Computer Numerical Control) machinery due to the high stiffness and accuracy provided by these machines, which are expensive and comparably big. For softer materials, such as aluminum, machining is possible using the less stiff industrial robot arm. This is attractive because the robot arm has a much lower cost than CNC combined with a larger work volume. Machining packages are now available for several robot brands, enabling robots to read and execute CNC G-code. It is particularly beneficial for small and medium enterprises. Robot arms are, however, less stiff and strong, resulting in less accuracy. In this thesis, the idea was that by using the IRB 2400 robot to mill typical process paths to evaluate the performance and part accuracy in robotic machining of aluminum alloy. A pre-study towards a standard proposal for measuring robotic machining performance was performed. Proper process parameters for robotic milling were applied, and the robot’s task was to repeatedly mill parts in different postures. The path accuracy, microstructure, and milling forces were analyzed. Results showed that the posture of the robot has a significant effect on path accuracy. With a proper posture, the path accuracy could be under 0.01mm.