A path planning method for surface damage repair using a robot-assisted laser cladding process

Repair is a critical step in restoring end-of-life components into their original shape or new functionality that contributes to sustainability for society. One of the advanced technologies to repair is the laser cladding process, which is an additive manufacturing technique for restoring metal component surfaces, e.g., a cylindrical shaft or downhole tools. Repairing surface damage has been challenging for several reasons, including the complexity of the path planning process. According to the literature, many researchers have focused on an automatic generation of the toolpath for laser cladding; however, most studies were developed for model building rather than repair. Thus, a general wear rebuild method is required for various types and shapes of damage. In addition, the development of a robust and effective method is feasible. This paper proposes a method to generate laser tool paths for surface damage based on a layer-by-layer rebuild approach. With reverse engineering techniques, acquired spatial measurements of the damaged surface, using a depth sensor, are employed to reconstruct the surface topology using the Delaunay method. Further, a surface unwrapping process is applied for the reconstructed mesh. Then, a new surface mesh slicing technique is developed to obtain rebuilding slices. This allows for independent path planning per layer. A unique feature of this method is the ability to control clad orientation per layer, which allows for a cross-hatching pattern path. In addition, processing normal vectors are computed to enable surface following cladding process with a minimal change in the tool's orientation and movement. Furthermore, the proposed method was tested with three practical case studies, which resulted in an effective toolpath. Lastly, the generated paths are verified in a simulated environment before producing the robot program. In the future, a practical repair process will be carried out to further investigate the effectiveness of this method and perform a metallurgical study of the clad.