Evaluation of Offline Path Planning for Laser Metal Deposition on Freeform Surfaces

The thickness of a layer made by Laser Metal Deposition (LMD) on a freeform surface varies depending on the local angle of inclination and the tool path direction. When depositing multiple layers, the CAM (Computer-Aided Manufacturing) planning for the tool paths requires an accurate description of the surface topography of the previous layers to ensure a stable process. Offline path planning is commonly based on the translation of the surface in the building direction (z-offset) or in the direction of the plane normal after each layer. In this paper, troughs with freeform surfaces are filled via LMD. The surface topography is measured after each layer and its deviation against the calculated surface according to z-offset and plane normal method is evaluated. Advice is given on which method of offline path planning is preferable and if additional controlling measurements of the surface are necessary after a certain amount of layers.