Influences of powder morphology and spreading parameters on the powder bed topography uniformity in powder bed fusion metal additive manufacturing

Mussatto, Andre; Groarke, Robert; O’Neill, Aidan; Obeidi, Muhannad Ahmed; Delauré, Yan; Brabazon, Dermot

doi:10.1016/j.addma.2020.101807

Cited by 64 publications

(48 citation statements)

References 37 publications

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“…However, process monitoring in polymer powder bed fusion is generally absent in industrial-grade commercial systems and remains an expensive yet unproven option even in metal laser powder bed fusion, for example with the optical tomography (OT) monitoring systems (with either visible or infrared light) provided with either visible or infrared recording such as the EOS EOSTATE Exposure OT [ 6 ]. As reported by Mussatto et al [ 7 ], powder morphology, spreading conditions and the interaction of the particles influence powder bed topography, and error-free spreading is crucial in order to minimize process failures such as short-feeds or voids such as the ones shown by Xiao et al [ 8 ]. If not corrected in time, these process anomalies can lead to reduced yield with consequences in both environmental and profitability terms.…”

Section: Introductionmentioning

confidence: 99%

Powder Surface Roughness as Proxy for Bed Density in Powder Bed Fusion of Polymers

et al. 2021

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Powder bed fusion of polymers is becoming increasingly adopted by a variety of industries to tailor the strength, weight and functionality of end-use products. To meet the high standards of the modern manufacturing industry, parts built with powder bed fusion require consistent properties and to be free of defects, which is intrinsically connected to the quality of the powder bed prior to melting. The hypothesis of this work is that the roughness of the top surface of an unmelted powder bed can serve as a proxy for the powder bed density, which is known to correlate with final part density. In this study, a laser line scan profilometer is integrated onto the recoater arm of a custom powder test bench, which is able to automatically create layers of powder. A diverse group of polymers was investigated including polyamide 12 (PA12), polyamide 11 (PA11), polypropylene (PP), and a thermoplastic elastomer (TPU) under different recoating speed in order to increase the variance of the dataset. Data analytics were employed to compare roughness to measured powder bed density and a statically significant correlation was established between them.

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Section: Introductionmentioning

confidence: 99%

Powder Surface Roughness as Proxy for Bed Density in Powder Bed Fusion of Polymers

et al. 2021

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“…Particularly for metal powders used in PBF, a very recent study investigated the effect of spreading velocity, layer thickness, and powder morphology on layer uniformity. In brief, it was shown that texture and sphericity were important to define the spreader velocity which was critically important for the uniformity of the powder [13]. Other studies focused on the role of particle-related properties (particle size distribution, morphology, flowability, etc.)…”

Section: Introductionmentioning

confidence: 99%

Spreadability of Metal Powders for Laser-Powder Bed Fusion via Simple Image Processing Steps

Vakifahmetoğlu

Hasdemir

2021

Preprint

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This paper investigates the spreadability of the spherical CoCrWMo powder for Laser-Powder Bed Fusion (PBF-LB) by using image processing algorithms coded in MATLAB.Besides, it also aims to examine the spreadability correlation with the other characteristics such as flow rate, apparent density, angle of repose. Powder blends in four different particle size distributions are prepared, characterized, and spreadability tests are performed with the PBF-LB. The results demonstrate that an increase in fine particle ratio by volume (below 10 µm) enhances the agglomeration and decreases the flowability, causing poor spreadability.These irregularities on the spread layers are quantified with simple illumination invariant analysis.

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“…The second phenomenon leads to satellitessmall particles stuck on the surface of larger ones (Figure 2). Satellites are associated with a decrease in flow and may lead to a decrease in the quality of spread layers, although this latest point is still under investigation [7,12]. Primary breakup occurs as soon as the gas hits the metal.…”

Section: Introductionmentioning

confidence: 99%

Simulations of gas flow in gas atomisation of liquid metals and validation experiments

Hulme-Smith

Kamalasekaran

Sundin³

2021

ICLASS

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The production of metal powder by gas atomisation generates feedstock for many manufacturing techniques, including hot isostatic pressing, laser cladding and, of current interest, powder bed additive manufacturing. While many thousands of alloys are commercially available in bulk form, fewer than fifty are widely available as powders suitable for additive manufacturing. This is due to difficulties in controlling droplet size distribution and avoiding particle defects. Indeed, a typical gas atomisation process that attempts to make powder for powder bed additive manufacturing achieves a yield of suitable powder below 50%. Several studies have simulated the gas atomisation process or part of it, but few validate the models directly. The current work aims to take a first step towards making a holistic and fully validated model for gas atomisation. The gas flow from de Laval nozzles under conditions similar to those used in gas atomisation has been simulated using computational fluid dynamics and experiments to validate these simulations have been performed using shadowgraphy. A validated model can be used as part of a larger model to predict the phenomena that occur in gas atomisation and thereby refine the process to improve the production yield of powders, especially for additive manufacturing.

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Influences of powder morphology and spreading parameters on the powder bed topography uniformity in powder bed fusion metal additive manufacturing

Cited by 64 publications

References 37 publications

Powder Surface Roughness as Proxy for Bed Density in Powder Bed Fusion of Polymers

Powder Surface Roughness as Proxy for Bed Density in Powder Bed Fusion of Polymers

Spreadability of Metal Powders for Laser-Powder Bed Fusion via Simple Image Processing Steps

Simulations of gas flow in gas atomisation of liquid metals and validation experiments

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