Investigating the effect of nonuniform forced convection on local polymer properties and geometric fidelity in fused filament fabrication

Fused Filament Fabrication (FFF) suffers from low print quality when process-induced heating and cooling are not well controlled. Cooling from hotend fans has not been characterized, and its effect on print quality has not been quantified. This work uses a thermocouple array to measure interactions between the cooling fan and heated print bed with and without printing. Polylactic acid (PLA) cubes were printed to investigate the effect of the fan on print quality in terms of surface roughness, area ratio, and shrinkage distance; these cubes exhibited significant, nonuniform differences in quality due to fan cooling. Uncooled regions were up to 167% rougher than cooled regions, while the average shrinkage distance increased by over 500% as a function of fan activation layer. Ultimately, this work shows that fan effects should not be neglected in FFF heat transfer models, and fan settings should be carefully considered to produce high-quality prints.