Effects of Printing Parameters on the Quality of FFF Printed Parts with Red PLA Filaments from Different Suppliers

The development of open-source movements in Fused Filament Fabrication (FFF) was important for the popularization of the technology for different levels of users, but also for motivating the emergence of companies focused on manufacturing machines and printing materials. Many material options are available on the market, with varied polymer bases and types of additives, among which pigments stand out. However, frequently, the effect of the pigment in the parameterization process and in the final quality of parts is neglected by the suppliers, and that often becomes a problem for printing. Recent studies show that for the same supplier, color variation in Polylactic acid (PLA) filaments is a significant factor for changes in mechanical properties, especially when the pigment is red. There was an opportunity to develop a study in which the color factor is fixed (red), and the influence of different filament suppliers is evaluated in the parametric configuration planning and, consequently, in the integrity of the parts obtained. Red PLA filaments of three brands were selected, which were input elements for a three-part investigation. First, the filaments were characterized by Fourier Transform Infrared Spectroscopy (FTIR), Dynamic Mechanical Analysis (DMA), and density measurement. In the second moment, a Taguchi experiment was used to evaluate the flexural mechanical properties and mass of the parts, considering the variation of layer thickness, extrusion temperature, print speed and extrusion multiplier, each one with three levels. The best levels of phase two parameter for each supplier were used to create a verification print model which manufactured parts were evaluated by the same responses as in the previous step. Finally, the results were compared to those from a fixed parameter setting from the literature. FTIR, DMA, and density analysis showed that red PLAs from different suppliers have similar responses. Parametrically, the red PLA filaments behaved differently, requiring, in some cases, specifics machines to produce the parts. In all cases, the verification models made the responses better than those identified with a fixed setting from the literature, which demonstrates the need for the user to adapt the system according to the supplier chosen, especially in controlling the extrusion flow rate. In summary, despite using the same polymer base (PLA), different suppliers possibly use their own sets of additives either to modify the color or stabilize the material. This affects the rheology and thermal behavior of the polymers, which requires unique printing settings, altering mechanical properties, and mass of parts. The study also highlights the importance of considering the determination of quality regulatory mechanisms in the production and commercialization of pigmented thermoplastic filaments for 3D FFF printing.