Additive manufacturing (AM) is rapidly becoming one of the most popular manufacturing techniques for short run part production and rapid prototyping. AM encompasses a range of technologies, including powder bed fusion (PBF) process. The purpose of this paper is to evaluate and benchmark the mechanical performance of polyamide 12 (PA12) parts, fabricated using a production scale powder bed fusion printing process (HP Multi Jet Fusion printing process). This system has a build volume is 380 x 254 x 350 mm. The printed polymer parts were examined to determine their hydrophobicity, morphology, porosity and roughness. Chemical and thermal properties of the PA12 parts were also evaluated using attenuated total reflection infrared spectroscopy (ATR FT-IR), x-ray photoelectron spectroscopy (XPS) and differential scanning calorimetry (DSC). The study highlights the influence of build orientation on the tensile (ISO 527-1:2012) and flexural (ISO 178:2010) properties. In terms of tensile strength, the parts exhibited isotropic behaviour with a maximum tensile strength of 49 MPa. In terms of flexural testing, the build orientations had a significant effect on the strength of the printed part. The Z orientation exhibited a 40% higher flexural strength, when compared to that of the X orientation. The maximum flexural strength observed was 70 MPa. The results of this rapid, production scale AM study are compared with previous studies that detail the mechanical performance of PA12, fabricated using PBF processes, such as selective laser sintering.

3D-printed parts in PEEK for flow chemistry and continuous processing produced using fused filament fabrication.

Continuous fiber-reinforced polymer composites have found a wide range of applications in the automotive and aerospace industry due to their lightweight properties. Recently the use of additive manufacturing (AM) has been developed for the fabrication of these composites. This study investigates the use of both atmospheric and, for the first time, low-pressure (1 Pa) processing conditions for the AM of continuous carbon, glass, and Kevlar fiber-reinforced nylon composites. Differential scanning calorimetry was used to compare the thermal properties of the three types of fiberreinforced filament prior to printing. It was found that the melting peak was dependent on filament type, which can be related to the polymer processing conditions used during their fabrication. Based on computed tomography measurements, it was found that the use of low-pressure printing conditions yielded a reduction in porosity for the carbon, glass, and Kevlar printed composites of 5.7%, 1.0%, and 1.7%, respectively.The mechanical properties of the composites were compared, using a short beam shear test, which assisted in the measurement of interlaminar properties. An increase in interlaminar shear strength of 33%, 22%, and 12% was obtained for the carbon, glass, and Kevlar fiber-reinforced polymer composites, respectively, when printed under low pressure, compared with that obtained at atmospheric pressure. K E Y W O R D S3D printing, additive manufacturing, fiber-reinforced polymeric composite, low pressure, vacuum