Investigating the effects of extrusion temperatures and material extrusion rates on FFF-printed thermoplastics

Abstract

Fused filament fabrication (FFF) is one of the most widely used additive manufacturing processes in the market. It is based on material extrusion and utilises thermoplastic materials to manufacture bespoke products. The process is extremely popular due to its ease of operation and variety of available materials. To enhance the mechanical performance of parts made by FFF, reinforcements including nanoparticles, short or continuous fibers and other additives have been added to commonly used thermoplastics such as acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA). Such new materials require optimization of process parameters to achieve the desired results. One such parameter is the material extrusion rate that can result in under or over extrusion leading to a variety of applications. In this study, PLA and HDPlas® PLA-GNP-A (PLA reinforced with functionalized graphene nanoplatelets) have been used to investigate the effects of material extrusion rate. An extensive comparative analysis has been provided where parts have been manufactured using a desktop 3D printer with the two materials at four extrusion temperatures (180 °C, 190 °C, 200 °C and 210 °C) and ten different extrusion rates (ranging from 70% to 160%). The study aims to evaluate the effects of extrusion temperatures and material extrusion rates on mass, dimensional accuracy, surface texture and mechanical properties of the two materials. Microstructural analysis has also been carried out to evaluate the surfaces of parts after manufacture as well as their fractured surfaces after mechanical testing to determine the impact of extrusion rate on failure modes. The results have shown that the graphene reinforced PLA material is affected more adversely by changes in material extrusion rate compared to PLA. This work provides a good comparison between two materials manufactured at four different extrusion temperatures and how the material extrusion rate can be leveraged to achieve optimal surface finish and mechanical strength.

The Influence of the Printing Temperature and the Filament Color on the Dimensional Accuracy, Tensile Strength, and Friction Performance of FFF-Printed PLA Specimens

“…The fixed parameters were as follows: the layer thickness (0.2 mm), targeting both acceptable values for the ultimate tensile strength (UTS) and the printing duration [ 12 ]; the build plate temperature (60 °C), as recommended by the filament producer; the printing speed (50 mm/s), higher than the value mentioned by the filament producer, in order to reduce the printing time of the samples and also considering previous research [ 12 , 23 , 24 , 26 , 31 ]; the build orientation (YX) and the raster angle (45°/−45°) for better mechanical properties [ 12 ]; and the infill density (100%), in order to minimize the influence of this parameter on the printed samples’ mesostructure.…”

“…Regarding the influence of the printing temperature on the mesostructure and its effect on the part’s mechanical properties, it is unanimously accepted that too-low temperatures cause under-extrusion defects (delamination of successive layers, larger gaps between raster lines) and thereby lower tensile strength. On the other hand, too-high selected printing temperatures lead to negative effects of over-extrusion, consisting of voids caused by filaments with too-low viscosity (bubbles determined by unsteady flow from the nozzle, layer drooping, stringing, oozing), also diminishing the tensile strength [ 15 , 21 , 24 ]. The selection of the proper printing temperature, avoiding under- and over-extrusion, has a positive effect on the part’s compactness and thereby on its tensile strength [ 4 , 7 , 11 , 13 , 22 , 23 , 25 , 26 ].…”

“…Regarding the color of the PLA filament, previous research showed that its influence on the dimensional accuracy [ 1 , 34 ] and the tensile strength [ 17 , 18 , 27 , 29 ] of FDM-printed samples cannot be neglected, and that also the same color PLA filaments manufactured by different producers, may not have the same printing properties [ 24 ]. The reasons behind this are considered to be the color-dependent in-process crystallinity and/or the different thermal behavior [ 17 , 34 ] in the case of PLA filaments containing coloring additives.…”

Microwave assisted hydrothermal synthesis of Bi2O3 /Ag2O heterostructures with highly enhanced photocatalysis and their biological interest

“…3, d). The Ra value (Surface Roughness) represents the average of numerous surface valleys or peaks measurements taken from different samples [27] Peak of Phonon resonance for Bi 2 O 3 exhibited at 631.82 cm − 1 is attributed with Bg mode [29]. Last peaks for both oxides at 889.32 cm − 1 appeared shifted, this can be the reason for the changes in surface strain and defects caused by the interaction of Bi 2 O 3 and Ag 2 O into the structure.…”

Development of Biodegradable PLA/PBAT-Based Filaments for Fertilizer Release for Agricultural Applications

“…Allied to the use of biodegradable plastics for sustainability, industry 4.0 presents itself as a crucial tool in increasing productivity and efficiency in the planning and control of products in several segments, with agricultural development being the most recent. Additive manufacturing, one of the pillars of this new industry, comprises a low-cost, efficient, easy-to-operate production technique which provides a wide variety of materials that can be used in versatile applications [ 22 , 23 , 24 ] ranging from biomedical, automotive and aerospace applications as well as prototyping industries in general [ 25 ].…”