Using Genetic Algorithms to Optimize the Build Orientation for Fused Deposition Modeled Components Containing Internal Reinforcement Structures

Fused Deposition Modeling (FDM) is an additive fabrication process that builds a part from extruded filaments of a melted thermoplastic. Typically, the parts are built using a ‘solid’ (complete fill) or ‘shell’ (3–4 mm external boundary with a loose internal weave) strategy. The introduction of parametric internal structures to support the required tensile or compressive loads provides an intermediate solution to the standard build options, and reduces the material usage while reinforcing the part as required. The internal structures can have a hexagonal, pyramidal, or orthogonal configuration. Because of the configuration variation, the internal structure form arrangement and geometric structure will influence the optimal build orientation. This will have an effect on the productivity or build time, mechanical properties such as strength, surface finish, materials usage and the total build cost. This paper presents a model to optimize the orientation of a part for FDM fabrication while considering these various factors. The CAD part model (in STL format) is an input to the system. A genetic algorithm is used to obtain optimum orientation of the parts for FDM. The objective function for optimization is considered a weighted average of the performance measures such as build time, part quality, material usage, surface finish, interior geometry, strength characteristics, and related parameters. The merits of the approach will be demonstrated using models with varying levels of complexity. The final model tested consists of a human tibia.