Hybrid manufacturing approaches, combining additive with subtractive manufacturing technologies, offer superior material efficiency compared to traditional subtractive manufacturing techniques. However, metal powder-based additive manufacturing methods reduce this advantage due to unavoidable powder loss. Additionally, most additive manufacturing processes necessitate the use of support structures to fabricate overhanging geometrical features, further compromising material efficiency. This study presents a hybrid manufacturing strategy that employs a wire-based Directed Energy Deposition (DED-LB-w/M) process in combination with an 8-axis robotic system. The strategy aims to maximize material efficiency while maintaining geometric flexibility and accuracy. The system integrates a 6-axis robotic arm with a turn-tilt table, enabling the fabrication of overhangs without the need for additional support structures by applying a non-parallel slicing method. The developed strategy requires local control of the deposition rate to create a tilted layer surface while maintaining continuous deposition. First, we give an overview of robot-based hybrid manufacturing and its challenges followed by a description of the experimental setup. Based on this, the limitations of the robot system regarding dynamical behavior as well as positional accuracy and the resulting constraints to the permissible process parameters are investigated. Finally, the manufacturing strategy is validated by manufacturing demonstrator parts and analyzing the process stability as well as reproducibility.
Science Journal 