Minimizing voids for a material extrusion-based process

After experimental testing, it was recognized that a component’s strength relationship with respect to the volume material usage is inconsistent and that failures occurred in regions of voids. The purpose of this study is to present an optimal toolpath for a material extrusion process to minimize voids and discontinuities using standard parameters and settings available for any given machine.

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. Fortus 400 machine build parameters are used for the case studies presented here. Optimal relationships are established based on the geometry and are to be applied on a layer-by-layer or sub-region basis and available machine build options. The component geometry is analyzed and decomposed into build regions. Matlab® is used to determine a standard (available) toolpath parameters with optimal variables (bead height, bead width, raster angle and the airgap) for each layer/build region.

It was found that the unwanted voids are decreased by up to 8 per cent with the new model. The final component will contain multiple bead widths and overlap conditions, but all are feasible as the available machine solutions are used to seed the model.

Unwanted voids can create failure points. Introducing an optimization solution for a maximized material fill strategy using existing build options will reduce the presence of voids and will eliminate “chimneys” or a void present in every layer of the component. This solution can be implemented using existing machine-toolpath solutions.

This study demonstrates that existing build settings and toolpath strategies can be used to improve the interior fill by performing targeted optimization strategies for the build parameters.