Influence of printing parameters on the stability of deposited beads in fused filament fabrication of poly(lactic) acid

Abstract

Fused filament fabrication (FFF) is one of the various types of additive manufacturing processes. Similar to other types, FFF enables free-form fabrication and optimised structures by using polymeric filaments as the raw material. This work aims to optimise the printing conditions of the FFF process based on reliable properties, such as printing parameters and physical properties of polymers. The selected polymer is poly(lactic) acid (PLA), which is a biodegradable thermoplastic polyester derived from corn starch and is one of the most common polymers in the FFF process. Firstly, the maximum inlet velocity of the filament in the liquefier was empirically determined according to process parameters, such as feed rate, nozzle diameter and dimensions of the deposited segment. Secondly, the rheological behaviour of the PLA, including the velocity field, shear rate and viscosity distribution in the nozzle, was determined via analytical study and numerical simulation. Our results indicated the variation in the shear rate according to the diameter of the nozzle and the inlet velocity. The shear rate attained its maximum value near the internal wall at high inlet velocities and smaller diameters. Finally, the distribution of the viscosity along the radius of the nozzle was obtained. At high inlet velocity, several defects appeared at the surface of the extrudates. At the highest shear rates, the extrudates underwent severe deformation. The defects predicted via numerical simulation were reasonably consistent with that observed from an optical microscope. Hence, these results are effective for selecting the printing parameters (i.e. nozzle diameter, feed rate and layer height) to improve the quality of the manufactured parts.

Characterization and 3D printability of poly (lactic acid)/acetylated tannin composites

“…The relatively higher porosity of the dog bones caused during 3D printing may probably justify this finding (Filgueira et al, 2017). Another possible reason could be related to the poor interlayer adhesion of the printed specimens because the mechanical properties of printed part depends on the interlayer adhesion (Bakrani Balani et al, 2019). As a whole, the strength of printed specimen was very close to that processed by traditional manufacturing methods (Figure 4).…”

Performance Analysis of Colored PLA Products with a Fused Filament Fabrication Process

“…Shear rate values lower than 6 × 10 −2 s −1 were not used because the material degraded, as reported by Balani et al [19]. The viscosity variation field of the Crystal Clear was higher than that of the Onyx Black at all temperatures tested.…”

“…Shear rate values lower than 6 × 10 −2 s −1 were not used because the material degraded, as reported by Balani et al [19].…”

Optimization of Vibration Characteristics of Fused Deposition Modeling Color 3D Printer Based on Modal and Power Spectrum Method

“…The color 3D printer model is shown in Figure 5. After applying the boundary conditions (9) and (10) to the equation of the modal mode (3), (11) could be derived as:…”

“…For the FDM 3D printer, the mode of multi-nozzle cooperative work is mainly used for color printing, which will lead to a series of problems [6,7]. On the one hand, the accuracy of the 3D printer has always been its problem and limits its development to a certain extent due to its unique printing mode [8][9][10], especially when color products are printed, accuracy deviations are easily detected due to the existence of color boundaries, so the FDM color 3D printer requires higher accuracy [11]. On the other hand, with the generation and iterative improvement of the color multi-nozzle device, the weight of whole nozzle is increased compared with that of the single nozzle [12].…”