Printing vertical flat surfaces in thermoset big area additive manufacturing

Abstract

In extrusion-based additive manufacturing, achieving high surface quality typically involves using small layer heights to reduce the size of grooves between layers. However, this approach can be both less effective and time-consuming in big-area additive manufacturing. Therefore, the current focus is on investigating methods for printing with fewer layers without compromising surface quality. In this study, single-strand walls were printed using a two-component thermoset material, where different nozzle designs and printing strategies are explored to achieve the flattest possible surface. The success of each approach was evaluated by measuring the percentage of material that required removal to achieve a perfect vertical flat wall. The results suggested that incorporating vertical wings to contain the material in the desired shape was beneficial. Furthermore, the study introduced the idea of adjustable layer heights to mitigate layer deformation. This deformation is most noticeable in the initial layers but largely affects all subsequent printed layers. Finally, making the wings have an angle with regard to the printing direction or trapezoidal wings, served as a pressure funnel that produced the greatest improvement in surface quality. These changes allowed for a reduction of the amount of material which would need to be removed to achieve a flat wall without grooves from 14.3% for a standard print from a round nozzle, to 2.5% for an optimized strand. The research shows a promising path to producing entirely flat vertical structures, even when printing with still-deformable, thermoset materials in the context of big-area additive manufacturing.

Keywords

• Material extrusion additive manufacturing
• Thermoset polymers
• Big-area additive manufacturing
• Nozzle geometry
• Surface quality