A study on extruded filament bonding in fused filament fabrication

Abstract

Purpose The performance of parts produced by fused filament fabrication is directly related to the printing conditions and to the rheological phenomena inherent to the process, specifically the bonding between adjacent extruded paths/raster. This paper aims to study the influence of a set of printing conditions and parameters, namely, envelope temperature, extrusion temperature, forced cooling and extrusion rate, on the parts performance. Design/methodology/approach The influence of these parameters is evaluated by printing a set of test specimens that are morphologically characterized and mechanically tested. At the morphological level, the external dimensions and the voids content of the printed specimens are evaluated. The bonding quality between adjacent extruded paths is assessed through the mechanical performance of test specimens, subjected to tensile loads. These specimens are printed with all raster oriented at 90º relative to the tensile axis. Findings The best performance, resulting from a compromise between surface quality, dimensional accuracy and mechanical performance, is achieved with a heated printing environment and with no use of forced cooling. In addition, for all the conditions tested, the highest dimensional accuracy is achieved in dimensions defined in the printing plane. Originality/value This work provides a relevant result as the majority of the current printers comes without enclosure or misses the heating and envelope temperature control systems, which proved to be one of the most influential process parameter.

Influence of the Infill Orientation on the Properties of Zirconia Parts Produced by Fused Filament Fabrication

“…Two sources of overextrusion can be found in this study: the programmed overextrusion caused by the perimeter-infill overlap and the uncontrolled overextrusion by the changes in the filament diameter. In principle, the overextrusion of material is an effective way to reduce the porosity in FFF parts [ 67 , 68 ]. Nevertheless, an excessive overextrusion leads to a “flooding” of material between roads and structures such as the one shown in Figure 11 a [ 8 , 68 ].…”

“…In principle, the overextrusion of material is an effective way to reduce the porosity in FFF parts [ 67 , 68 ]. Nevertheless, an excessive overextrusion leads to a “flooding” of material between roads and structures such as the one shown in Figure 11 a [ 8 , 68 ]. Figure 11 b shows the origin of the overextrusion defects, which can eventually result in the apparition of new types of defects, as shown by Costa et al [ 68 ].…”

“…Nevertheless, an excessive overextrusion leads to a “flooding” of material between roads and structures such as the one shown in Figure 11 a [ 8 , 68 ]. Figure 11 b shows the origin of the overextrusion defects, which can eventually result in the apparition of new types of defects, as shown by Costa et al [ 68 ]. The shape and volume of these defects are different depending on the orientation between the roads of consecutive layers, as shown in Figure 11 c. With the 0° and 90° infill orientations the roads of the new layer are parallel to those already deposited, resulting in the defects reported by Costa et al In the specimens with the ±45° infill orientation, the new roads are perpendicular, which leads to new types of defects.…”

3D printed bismuth oxide‐polylactic acid composites for radio‐mimetic computed tomography spine phantoms

“…The tensile test specimens were printed with the flat side down and the long axis aligned with the x‐axis of the build platform. This orientation results in the majority of the deposited beads of material aligned parallel to the applied load, which has been shown to maximize the mechanical strength of printed specimens 27‐32 . Solid cylindrical specimens were printed with 8 mm diameters and 10 mm lengths for micro‐CT analysis (Figure 1b,c).…”

Effects of Environmental Temperature and Humidity on the Geometry and Strength of Polycarbonate Specimens Prepared by Fused Filament Fabrication

“…Spoerk et al printed polypropylene (PP) filled with glass spheres, which showed better annealing quality and dimensional accuracy with an elevated chamber temperature [ 17 , 18 ]. Carneiro et al found that a 20 °C increase in environmental temperature reduced the structural porosity of printed acrylonitrile butadiene styrene (ABS) by 50% [ 19 ]. Armillotta et al studied the specimen warpage with both analytical and experimental approaches, and they reported that a high chamber temperature close to the glass transition temperature significantly reduced the warpage [ 20 ].…”