Determining the relationships between the build orientation, process parameters and voids in additive manufacturing material extrusion processes

It stands to reason that the additive manufacturing build orientation for the material extrusion process affects the support material requirements, processing time, surface finish, etc. This paper aims to study the influence of the build orientation on the optimal process parameter settings (bead width, overlap, and raster angle), the amount, and location of unwanted voids. This research shows that there are limited optimal solution alternatives over the large solution space explored. The layer by layer process parameters are not selected independently. Knowledge of a void location in one layer is utilized to select a process parameter set for the next layer, preventing void regions from being stacked in 3D, and avoiding creating an internal chimney. Material extrusion processes, with a wide selection of nozzle sizes (0.4mm to 21mm), are considered suitable candidates for this solution. To carry out this study, a literature review was performed to understand the influence of the build parameters. Then, an analysis of valid parameter settings to be targeted was performed for a commercial system. The mathematical model is established based on the component geometry and the available build options for a given machine-material configuration. A C++ program has been developed to select a set of standards (available) toolpath parameters to determine the optimal process variables. Case studies are presented to show the merits of this approach. The influence of the orientation on the optimal process parameters is illustrated as well as its impact on voids. As expected, it is statistically shown that the amount and location of the voids depends on the build orientation. The optimal solution for the void minimization may be suboptimal for other criteria such as support material usage; consequently, a comprehensive multi-objective optimization heuristic algorithm needs to be developed. The processing time is long and is unacceptable for industrial applications. This outcome also needs to be addressed.