The Influence of Particle Shape, Powder Flowability, and Powder Layer Density on Part Density in Laser Powder Bed Fusion
04 Mar 2021-Vol. 11, Iss: 3, pp 418
TL;DR: In this paper, the relationship between these properties and their influence on final part density for six 1.4404 (316L) powders and eight AlSi10Mg powders was investigated, and the results showed a correlation of the powder properties with a Pearson correlation coefficient (PCC) of −0.89 for the PLD and the Hausner ratio.
Abstract: The particle shape influences the part properties in laser powder bed fusion, and powder flowability and powder layer density (PLD) are considered the link between the powder and part properties. Therefore, this study investigates the relationship between these properties and their influence on final part density for six 1.4404 (316L) powders and eight AlSi10Mg powders. The results show a correlation of the powder properties with a Pearson correlation coefficient (PCC) of −0.89 for the PLD and the Hausner ratio, a PCC of −0.67 for the Hausner ratio and circularity, and a PCC of 0.72 for circularity and PLD. Furthermore, the results show that beyond a threshold, improvement of circularity, PLD, or Hausner ratio have no positive influence on the final part density. While the water-atomized, least-spherical powder yielded parts with high porosity, no improvement of part density was achieved by feedstock with higher circularities than gas-atomized powder.
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TL;DR: A comprehensive and state-of-the-art study on the Selective Laser Melting (SLM) process regarding the types of materials used, the printing of reflective material and multi-materials, the effect of several process parameters on thermo-mechanical properties of parts, printing of lattice structure, a novel support structure technique, types of post-processing methods, and basic information on simulation software used for SLM processes is provided in this article .
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TL;DR: In this paper, a discrete element method is used to examine the mechanisms determining powder deposition efficiency during powder spreading in powder bed fusion additive manufacturing, and the results reveal that powder flow in the powder pile is critical for the formation and break of transient jamming.
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TL;DR: In this article , a discrete element method is used to examine the mechanisms determining powder deposition efficiency during powder spreading in powder bed fusion additive manufacturing, and the results reveal that powder flow in the powder pile is critical for the formation and break of transient jamming.
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TL;DR: In this paper , the deformation mechanism of GA powder depending on the ball milling media was discussed based on the developed particle morphology distribution map and contact mechanics simulation, and the variation of surface and electrical properties by mechanical stimulation was investigated via XPS, TEM, Impedance analysis.
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TL;DR: In this article, six standardized methods (measuremention of bulk density by ISO 60 and by ASTM B329, angle of repose by ISO 4324, discharge time by ISO 6186, and Hausner Ratio (Hausner ratio) and powder rheometry (Anton Paar powder cell) were compared to five size fractions of a crushed quartz sand powder.
Abstract: The flow behavior of powders has an essential role in many industrial processes, including powder bed additive manufacturing. The characterization of the flow behavior is challenging, as different methods are available, and their suitability for an application in additive manufacturing is still controversial. In this study, six standardized methods (measurement of bulk density by ISO 60 and by ASTM B329, angle of repose by ISO 4324, discharge time by ISO 6186 and by ASTM B964–16, and Hausner Ratio by ASTM 7481–18), the rotating drum method (by GranuDrum) and powder rheometry (Anton Paar powder cell), were applied to five size fractions of a crushed quartz sand powder and compared. A statistical approach is proposed and discussed to correlate the obtained flowability indexes with the packing density of powder beds deposited layer-by-layer, and these correlations are compared between methods. Overall, the measurement of bulk density by ASTM B329 showed the best correlation with the powder bed density. Advanced methods such as the rotating drum method and powder rheometry did not demonstrate particularly good correlations, however they provided complementary information which can be useful to assess the dynamic behavior of powders.
9 citations
References
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TL;DR: In this article, the densification and microstructural evolution during direct laser sintering of metal powders were studied, and it was found that when melting/solidification approach is the mechanism of sinter, the densifiers of metals powders (D ) can be expressed as an exponential function of laser specific energy input ( ψ ) as ln(1−− D )−= ǫ− Kψ.
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