Adaptive trajectories generation for additive manufacturing for structural parts with variable thickness

Wire Arc Directed Energy Deposition (WA-DED) has demonstrated its ability to produce thin metallic structures due to its high material deposition rate and freedom of movement. However, in additive manufacturing, the surface quality of the raw part depends on generating an optimized toolpath to limit defects on the final part. Traditional deposition strategies in manufacturing are often at a constant height and do not allow for the production of a wide range of topologies. WA-DED has the advantage of modulating the deposition height during fabrication, allowing the creation of complex shapes while increasing the final precision. This paper presents a new approach aimed at creating 3D trajectories with variable deposition height on curved layers for complex surfaces with variable thickness. This method is used on thick parts and thick parts with local thickness variation requiring local deposition of more than a single bead. This method is based on isothermal surfaces derived from a thermal conduction problem on the geometry to be manufactured, specifically adapted to overcome the problems of multi-bead deposition and disturbance of the thermal conduction flow induced by the variation in thickness of the part. The curved layers derived from isothermal surfaces serve as a support for creating the trajectories and a map of the inter-layer distance is calculated by ray casting. The trajectories, in the form of a pseudo-spiral, take into account the distance between the layers to adapt the deposition height, which varies across the surface to be fabricated. Finally, the fabrication order is carried out incrementally in the direction of fabrication. Numerical and experimental validation on a thin part with locally variable thickness, topologically optimized, has validated the effectiveness of the method.