Flatwise to Upright Build Orientations under Three-Point Bending Test of Nylon 12 (PA12) Additively Manufactured by SLS

Abstract

This paper describes in detail a series of static tests conducted in a three-point bend configuration on three build orientations (i.e., 0°, 45°, and 90°) of additively manufactured Nylon 12 (PA12) specimens produced with a powder refresh ratio of 50%, using a benchtop industrial SLS platform, Formlabs Fuse 1. The bending strength and flexural elasticity moduli are determined following ISO 173 specifications and by employing a more complex equation that considers the influence of large deflections as per ISO 14125 indications. Statistical variability of experimental data is considered and compared to the results from the literature. Through a fractographic SEM study, the damage morphologies of tested specimens are analyzed and associated with the recorded load-deflection curves for an accurate perception of build orientation-dependent anisotropy in bending properties of AM PA12 SLS specimens. A surprising result of this investigation is that the specimens built with 45° orientation showed superior modulus elasticity in flexure but a low bending strength compared to flatwise oriented specimens. In addition, a Weibull reliability quantification of bending strength is adapted to pinpoint the effects of internal 3D printing flaws (contained within a characteristic highly-stressed volume of material) over the failure probability of the three build orientations in question.

Surface Roughness and Grain Size Variation When 3D Printing Polyamide 11 Parts Using Selective Laser Sintering

“…In existing work, the position of the part has been studied from the laser beam properties perspective [50,51], and from a mechanical point of view, with some interesting results on differences in the crystallization rate [56]. Concerning the build setup, studies have focused on the build orientation as an overall property for improving the mechanical response to forces and loads [57,58]. The approach of the present study resembles the works of Strano et al [35] and Bacchewar et al [59].…”

Microfluidic Organ-on-A-chip: A Guide to Biomaterial Choice and Fabrication

“…Regarding SLS, this powder bed fusion technique uses a high-power laser to heat-treated polymeric particles to form the desired structures. Nylon, polystyrenes (PS), polyaryl-etherketones (PAEK), and polycaprolactone (PCL) are the familiar choices of material for this technique [ 159 , 193 , 194 ]. Similar to SLA, SLS is also ideal for complicated microstructures and geometries.…”

Three-Point Bending Response of Nylon 12 Obtained by Fused Filament Fabrication (FFF) Versus Selective Laser Sintering (SLS)

“…except for its high hygroscopicity, Nylon 12, also known by its chemical name Polyamide 12 (Pa12), generally prevail over these drawbacks. However, its strength, stiffness, and toughness have been mainly investigated for SLS forms in terms of processing parameters [15][16][17][18][19][20], build orientation, and anisotropy [21][22][23][24][25][26][27][28], optimization, morphology, and multiscale characterization [29][30][31], simulation and mechanical modeling [32][33][34][35], as well as comparisons to multi-jet fusion (mJf) technology [36][37][38]. here, it is worth noting that the literature references related to aM compound materials based on laser-sintered Pa12 were not mentioned above, as they are beyond the scope of this study.…”