Issue 62

D. D’Andrea et alii, Frattura ed Integrità Strutturale, 62 (2022) 75-90; DOI: 10.3221/IGF-ESIS.62.06

Prague, Czech Republic). The filaments studied were ABS, PETG and PLA from Sunlu producer (1.75±0.02 mm of diameter). On the extruder head there are two counter-rotating driving wheels that pull the filament and push it through a heating block and a hot nozzle. A tube made of polytetrafluorethylene (PTFE) guides the filament to the extruder unit. The unit also includes a sensor, which detects the incoming filament. FDM technology is based on the deposition of a plastic filament according to a precise sequence of instructions showing the displacement coordinates of the x, y, z axes of the 3D printer. These instructions are provided by a special file created by a slicing software that reconstructs the object one level at a time on the construction plane. After the material was molten, the FDM printer deposited a strand by moving the printing head according to the predefined geometry. This occurred in a layer-by-layer manner. After finishing the first layer, the height of the extrusion head was increased by the amount of one layer and the second layer was deposited. This process was repeated until a defined height of the geometry was reached. The used processing parameters are summarized in Tab. 1. Nozzle and build platform temperatures were chosen for each material to match the producer's material data sheet. To avoid further influences of different processing parameters, such as layer thickness, temperature, infill percentage, infill pattern, or printing speed on the mechanical properties, these were kept constants for all specimens produced in this study (Tab. 1). The printing infill was set to 100% to achieve the highest mechanical properties.

Parameters

ABS

PETG

PLA

Nozzle temperature [°C]

260

240

200

Bed temperature [°C]

90

90

90

Adhesion

Brim

Brim

Brim

Layer thickness [mm]

0.15

0.15

0.15

Printing speed [mm s − 1 ]

60

60

60

Printing infill [%]

100

100

100

Table 1: Processing parameters of ABS, PETG and PLA.

Three different print orientations were chosen for the filling. The approach used consists of positioning the geometries of the three specimens, already oriented in the three angles considered (0°, 45° and 90°) and setting a single filling angle in the FDM, i.e., 0 °. Fig. 2b shows the orientation of the specimens with the relative infill.

(a) (c) Figure 2: a) Orientation of the specimens with relative infill; b) Original Prusa i3 MK3S+, spool of filament and specimens. (b)

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