Computer supported toolpath planning for LMD additive manufacturing based on cylindrical slicing

In laser metal deposition of overhanging geometries, non-planar layers are used to partially avoid the highly inconvenient support structures. Multi-axis machines provide extra degrees of freedom that allow the deposition of non-planar layers. However, path planning for non-planar slicing is complex because, in most geometries, it encourages non-homogeneous metal deposition among the dispenser paths. For workpieces presenting a direction normal to which all cross sections have non-null common kernel (called here “revolute workpieces”), it is possible to use a cylindrical (i.e., iso-radial) slicing which still enables homogeneous path generation and metal deposition. This manuscript presents the implementation and experimental validation of a path-planner for laser deposition metal dispensers which build revolute workpieces by stacking iso-radial layers. Isometry is preserved between each 3D cylindrical layer and the 2D parametric space (κ, γ) where the dispenser path is planned, so deposed metal density can be homogenized. The path-planner takes advantage of the natural isometry between the (κ, γ) flat surface and the 3D cylinder (due to the cylinder developability). This isometry allows for (i) the application of conventional 2D dispenser path planning for 3D iso-radial layers and (ii) the control of inter-bead distance and dispenser velocity. The implemented path-planner also allows the control of the deposed thickness for each iso-radial layer. To validate experimentally our strategy, we manufacture spur and helical gear teeth on a cylindrical substrate. The results of these experiments show that our strategy generates toolpaths suitable for the manufacturing of industrial workpieces via laser metal deposition.