Characterization of the anisotropic thermal conductivity of additively manufactured components by fused filament fabrication

Recently, additive manufacturing (AM) has been successfully employed to fabricate heat exchangers due to its ability to create complex geometrical structures with high volumetric-to-area ratio, which can be designed to increase convective heat transfer from surfaces. Fused filament fabrication (FFF) is one of the most popular AM methods due to it is accessible and low-cost hardware. The effect of process parameters on the mechanical properties of FFF 3D-printed parts has been studied extensively. However, there are limited reliable data for the thermal conductivity of 3D-printed components which has impeded the development of additively manufactured heat exchangers. In the current study, the effect of the layer height and raster width have been investigated experimentally and numerically to characterize the effective thermal conductivity of 3D-printed components and investigate the thermal anisotropic nature of unidirectional printed parts. The results showed that increasing the layer height and width causes deterioration in the effective thermal conductivity of up to 65% of the pure polymer. In addition, the thermal conductivity was measured for a range of PLA composites and it was found that their anisotropic ratio can be as high as 2. The unidirectional effective conductivity model was subsequently modified to characterize the common cross-hatched layer fill configuration, and the influence of fill ratio on the effective thermal conductivity was investigated. Finally, the effective thermal conductivity of several commercially available PLA composite filaments was characterized experimentally.