Wire Arc Additive Manufacturing (WAAM) is the most suitable technology to manufacture thin-walled structures of large dimensions and medium geometric complexity at a reduced cost with an excellent Buy-to-Fly ratio. Nowadays, this technology permits to manufacture parts using 2.5D strategies, cutting a 3D model in parallel flat layers [1]. The complexity of the part shapes is limited by 2.5D strategies that can be manufactured in WAAM due to the use of 3 axis machines. However, it has been shown that a 6-axis strategy, combined with the modulation of the deposition height, allows a wide range of WAAM printable geometries [2]. The arc starts and stops from one to another, resulting in poor surface finish and residual stresses that can affect the mechanical strength of the part. Therefore, it is necessary to limit the phenomenon of the arc by limiting the arc stop and start phases [3] and to introduce the use of a 6-axis kinematics in order to obtain a better surface finish.

The objective of this work is to present a fast and efficient path planning strategy that increases the quality of the surface finish of the manufactured parts by limiting the arc stop and start phases. This method generates a three-dimensional continuous path for thin and massive parts using a scalar field based on heat propagation. The strategy can be declined in several types of geometries: mono-branch/multi-branch for thin [4] and massive parts but also thin parts that can be opened and closed. The proposed method allows to generate iso-contours (resp. iso-surfaces) using 3D geometry of shell type (resp. massive), thanks to a thermal scalar field. By coupling this scalar field with judiciously chosen boundary conditions, it permits to take into account the geometry edge effects. The consideration of these effects allows to create a continuous trajectory for shell parts and a trajectory as continuous as possible on massive parts. Moreover, the WAAM technology allows a modulation of the deposit height which will improve the versatility of this strategy. Indeed, the height difference between each iso-contour (resp. iso-surface) can vary along the manufacturing process. Finally, a reformulation of this approach will be proposed as an optimization problem aiming to make the trajectory as continuous as possible in critical areas. These regions can be either mechanical or thermal, and a reflection will be done on the different ways to write them in the context of a multivariate minimization problem.