Additive Manufacturing (AM) is the process of part building by stacking layers of material on top of each other. Various challenges for a metal powder based process include reducing the staircase effect which leads to poor surface finish of the part, and minimal use of support structures for regions with overhangs or internal hollow volumes. Part build orientation is a crucial process parameter which affects part quality, in particular, Geometric Dimensioning & Tolerancing (GD&T) errors on the part, the energy expended and the extent of support structures required. This paper provides an approach to identify an optimal build orientation which will minimize the volume of support structures while meeting the specified GD&T criteria of the part for a DMLS based process. Siemens PLM NX API is used to extract the GD&T callouts and associated geometric information of the CAD model. The regions requiring support structures are identified and a Quadtree decomposition is used to find the volume of support structures. The mathematical relationships between build orientation and GD&T are developed as part of a combined optimization model to identify best build orientations for minimizing support structures while meeting the design tolerances. The feasible build orientations along with the corresponding support structures are depicted using a visual model.

Additive Manufacturing (AM) incorporates a group of processes which utilize a layer-based material deposition approach to manufacture parts. These processes are now widely used in the industry as the primary manufacturing process for fabricating high precision parts. The dimensional accuracy of the parts and components manufactured using AM depend mainly on the type of Additive process used and the process parameters. The part build orientation is one of the principal process parameters which has a direct influence on the staircase effect and volume of support structure required for building the part. These factors eventually contribute to the surface finish, dimensional accuracy, and the post-processing requirements. In this paper, an optimization model is developed to obtain the build orientation which will minimize the support structure volume as well as support contact area and maximize the support structure removal while satisfying all the GD&T callouts. The mathematical correlation of cylindricity, flatness, parallelism, and perpendicularity tolerances with build orientation is analyzed and developed. A voxel-based approach is employed to calculate support structure requirement at any part build orientation, while a ray tracing approach is used to calculate the accessibility of supports and identifying removable supports.

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