Optimization of the geometry for the end lateral extension path strategy to fabricate intersections using laser and cold metal transfer hybrid additive manufacturing

Wire-feed additive manufacturing has great potential for building large-scale aerospace parts that commonly contain many grid-stiffened panel structures. The buildup of intersections in the grid tends to generate issues such as porosity, cracks, and surface unevenness. A solution to this problem, end lateral extension (ELE), was proposed in our previous work, in which the weld track was extended along the crossing section and provided moderate benefits. This paper continues to optimize the ELE path strategy. Single beads and intersections are deposited by laser and cold metal transfer (CMT) hybrid additive manufacturing. First, a surface quality metric for intersection builds is proposed based on the volume deviation between the given ideal CAD model and the scanned point cloud of the builds. This metric is used to optimize a set of parameters including start and end dwell times, weld current, travel speed, parallel path offset distance, extension and parallel path offset distance, and extension path length in the crossing. The experiments are designed using the response surface method (RSM). Quadratic models are developed to build relationships between the parameters and response variables, and the effects of the parameters on the response are analyzed. Then, variable optimization is performed to obtain the optimal settings. The validation WA with the optimal settings exhibits a significantly improved profile quality, which is acceptable in industrial practices.