Minimizing Voids With Using an Optimal Raster Orientation and Bead Width for a Material Extrusion Based Process

Abstract

Additive Manufacturing (AM) is the process of joining materials ‘layer by layer’ to make products from Computer Aided Design (CAD) model data. AM processes support faster product realization for a wide selection in industries. The Material Extrusion (ME) process is an AM process that builds a product from thin layers of extruded filaments from a semi-melted material such as a thermoplastic. In commercial systems, the software automatically generates the tool paths for both the model and any necessary supports, based on the curve geometry and the specified build parameters. The interior fill rotates 90° between each layer. Automatically generating the tool path can be the biggest weakness for this process planning strategy. Voids and discontinuities have been observed after evaluating test specimens developed to explore mechanical characteristics. Choosing an optimal raster orientation and bead width will help minimize voids and discontinuities in each layer. A mathematical model is introduced in this paper to find optimal raster orientation and bead widths based on the geometry of the slice for selected 2D extruded parts. As well, preliminary quality assessment metrics are introduced. Void analysis is performed to evaluate solution approaches, and the results compared. The future work will investigate utilizing multiple bead widths for a layer to minimize voids, and developing more comprehensive quality metrics to highlight problematic regions.