Influence of the printing parameters on the stability of the deposited beads in fused filament fabrication of poly(lactic) acid
Résumé
Fused Filament Fabrication (FFF) is one among a wide variety of processes of Additive Manufacturing. Similar to the others, FFF enables freeform fabrication and optimized structures, from. The aim of this work is to optimize the printing conditions in the FFF process based on reliable properties: printing parameters and physical properties of the polymer. The chosen polymer is poly(lactic) acid (PLA), a biodegradable thermoplastic polyester derived from corn starch and, as one of the most common polymers in the FFF process. the maximum inlet velocity of the filament in the liquefier is empirically determined according to process parameters such as the feed rate, the nozzle diameter and the dimensions of the deposited segment. Then, the rheological behavior of poly(lactic) acid including the velocity field, the shear rate and the viscosity distribution in the nozzle are determined by analytical study and numerical simulation. Our results show the variation of the shear rate according to the diameter of the nozzle and the inlet velocity. The shear rate reaches its maximum value for high inlet velocity and smaller diameters, near the internal wall. The distribution of the viscosity is obtained along the radius of the nozzle. For high inlet velocity, some defects appear at the surface of the extrudates. At highest shear rates, the extrudates undergo severe deformation microscopy. These results are valuable for choosing the printing parameters ( in order to improve the quality of the
manufactured parts.
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