Selected design rules for material extrusion-based additive manufacturing of alumina based nozzles and heat exchangers considering limitations in printing, debinding, and sintering

Recent developments in the area of material extrusion-based additive manufacturing (MEX-AM) make it possible to produce complex-shaped ceramic parts using a layerwise printing process. To achieve a dense ceramic part, the green printed body is post-processed in subsequent debinding and sintering steps. Only a very limited amount of works exist that study the design limits of 3D printed structures by the MEX-AM process, especially considering the effects of the subsequent post-processing steps. The knowledge of such restrictions or design limits is key to fabricating complex parts without process failures or part defects. In this study, a set of geometric test specimens to determine the minimum build angle, printability of arches, minimum wall thickness, and shrinkage after debinding and sintering were printed with a filament-based extrusion head. Based on the test specimens, the work presents a first set of design rules to consider the process restrictions due to MEX-AM and post-processing for alumina parts. The work shows how simple printing structures can be used to derive design rules to guide the design of a complex-shaped multi-flow nozzle and a heat exchanger based on alumina without additional support structures. Finally, the work discusses potential improvements for future studies.

Automated summary

Recent developments in material extrusion-based additive manufacturing (MEX-AM) have enabled the production of complex-shaped ceramic parts. However, there is limited research on the design limits of 3D printed structures using MEX-AM and post-processing steps. This study presents a set of design rules for fabricating alumina parts considering these restrictions, based on geometric test specimens and printed structures.