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Evaluation and optimisation of a slurry-based layer casting process in additive manufacturing using multiphase simulations and spatial reconstruction

 
: Erhard, Patricia; Seidel, A.; Vogt, Joachim; Volk, W.; Günther, D.

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Fulltext ()

Production Engineering. Research and development 16 (2022), No.1, pp.43-54
ISSN: 0944-6524
ISSN: 1863-7353
English
Journal Article, Electronic Publication
Fraunhofer IGCV ()
Fraunhofer ISC ()
additive manufacturing; 3D printing; ceramic; slurry casting; CFD; Simulation; multiphase; VOF; spatial reconstruction

Abstract
Slurry-based 3D printing allows ceramic green bodies to be fabricated at high packing densities. In contrast to powder-based binder jetting, full densification of printed parts can be achieved in a subsequent sintering step as fine particles dispersed in a suspension are cast and compacted. Slurry-based 3D printing is thus expected to overcome the application limits of the powder-based alternative in metal casting in terms of unfavorable properties like high surface roughness, low density and low mechanical strength. To ensure stress-free drying and therefore high qualities of the compounds made in layers, it is crucial to fabricate single layers with a high level of homogeneity. This paper presents a CFD model based on the open-source simulation environment OpenFOAM to predict the resulting homogeneity of a cast slurry layer with defined parameter sets or coater geometries using the Volume-Of-Fluid method. Moreover, a novel method of spatial reconstruction is proposed to evaluate the surface quality of layers on a minimised computional demand. By comparing the results of the simulation with the real macroscopic behaviour determined in experiments, the approach is found to be a useful tool for suggesting suitable parameters and coater geometries for processing slurries. A precise reconstruction of the outline of the coating area with different process parameters and an approximate prediction of the effect on surface roughness was achieved.

: http://publica.fraunhofer.de/documents/N-641999.html