Automated Scan-Based Remanufacturing Process Chain for High-Precision Milling of Turbine Blades

Turbine blades of industrial gas turbines exhibit sub-coating cracks after a certain period of operation. These cracks stem from thermal and mechanical strains. Turbine blades are complex parts with high material and manufacturing costs, making a repair attractive from economical and sustainability perspectives. After removal of the coating, to reach the crack depths, the base material needs to be removed. The conventional repair process is dominated by manual work, including defect detection, geometry parametrization and CAM path planning. The scope of this work is to replace time and labor-intensive work steps by an adaptive and automated subtractive repair process. The proposed digital process chain includes 3D scanning of the turbine blade, highly accurate 3D geometry reconstruction and subsequent automated path planning for the milling operation. Post-processing and milling are executed, and the actual results are compared to the reconstructed and planned geometry, showing that satisfactory accuracy can be achieved. The overall time is drastically reduced compared to the conventional process. Finally, the potential for optimization and industrialization is discussed.