Dynamic investigation on the powder spreading during selective laser melting additive manufacturing

Yao, Dengzhi; An, Xizhong; Fu, Haitao; Zhang, Hao; Yang, Xiaohong; Zou, Qingchuan; Dong, Kejun

doi:10.1016/j.addma.2020.101707

Cited by 38 publications

(21 citation statements)

References 38 publications

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“…The density after 1000 times of tapping was estimated from these results using the Kawakita equation 19) as the tapping density. In calculating the packing density and tapping density, to avoid the wall effect, 5,12) the density was calculated using the center region where the apparent density was almost constant. In this study, the surface energy density and friction coefficient were determined to be 0.06 J•m ¹2 and 0.3, respectively, from the results of the packing and tapping simulations.…”

Section: Models and Simulation Conditionsmentioning

confidence: 99%

Experimental Characterization and Computational Simulation of Powder Bed for Powder Bed Fusion Additive Manufacturing

et al. 2022

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The packing density of powder bed is one of the critical parameters affecting the quality of the final parts fabricated via powder bed fusion additive manufacturing. In this study the packing density of the first layer of the powder bed was experimentally estimated from the packing densities of recoated powder with different number of layers. It is found that the packing density of the first layer is much lower than the apparent density of powder and the macro-scale packing density increases as the number of recoated layer increases. Furthermore, recoating simulation using discrete element method (DEM) was conducted to investigate the deposition mechanism of the powder at the particulate-scale. The simulation results showed the packing density of powder bed increases as the number of recoated layer increases, similar to the experimental results. This is caused by the rearrangement of the powder in the powder bed stimulated by the supplied powder. Also, the packing density of the powder bed was not uniform in the thickness direction, and the top surface layer which affects the quality of manufactured parts had almost the same packing density as that of the first recoated layer independently of the number of recoated layers.

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Section: Models and Simulation Conditionsmentioning

confidence: 99%

Experimental Characterization and Computational Simulation of Powder Bed for Powder Bed Fusion Additive Manufacturing

et al. 2022

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“…The main cause of the consequences is a variation of the powder packing density from one location to another along the powder spreading direction. This variation was caused by the influence of the flow mechanism among different sizes of powder particles during powder layering [16,17]. The frictional and gravitational forces played a decisive role in the flow mechanism of the powder [13].…”

Section: Primary Cause: Powder Packing Densitymentioning

confidence: 99%

“…On their way from the powder feed chamber to the overflow chamber, the particles pass through the shaking and rolling movement [13]. These movements intensify the filtering and aggregation, which leads to a different packing density of the powder bed [16].…”

Section: Introductionmentioning

confidence: 99%

The effects of locations on the build tray on the quality of specimens in powder bed additive manufacturing

Pal

Gubeljak

Bončina

et al. 2021

Int J Adv Manuf Technol

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In this study, the effect of powder spreading direction was investigated on selectively laser-melted specimens. The results showed that the metallurgical properties of the specimens varied during fabrication with respect to their position on the build tray. The density, porosity, and tensile properties of the Co–Cr–W–Mo alloy were investigated on cuboid and tensile specimens fabricated at different locations. Two different significant positions on the tray were selected along the powder spreading direction. One set of specimens was located near the start line of powder spreading, and the other set was located near the end of the building tray. The main role in the consequences of powder layering was played by the distribution of powder particle sizes and the packing density of the layers. As a result, laser penetration, melt pool formation, and fusion characteristics varied. To confirm the occurrence of variations in sample density, an additional experiment was performed with a Ti–6Al–4V alloy. Furthermore, the powders were collected at two different fabricating locations and their size distribution for both materials was investigated.

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“…The results showed that the continuity and stability of the powder flow decrease with the increase in powder spreading speed and the decrease in powder spreading layer thickness, which lead to the deterioration of the bulk density and uniformity. Yao et al [ 26 ] simulated the powder laying process with a 316L stainless steel powder scraper. The effects of technological parameters, the scraper structure, and the powder particle size on the powder laying quality were studied.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Effects of Roller Spreading Parameters on Powder Bed Quality in Selective Laser Sintering

et al. 2022

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Powder spreading is one of crucial steps in selective laser sintering (SLS), which controls the quality of the powder bed and affects the quality of the printed parts. It is not advisable to use empirical methods or trial-and-error methods that consume lots of manpower and material resources to match the powder property parameters and powder laying process parameters. In this paper, powder spreading in realistic SLS settings was simulated using a discrete element method (DEM) to investigate the effects of the powder’s physical properties and operating conditions on the bed quality, characterized by the density characteristics, density uniformity, and flatness of the powder layer. A regression model of the powdering quality was established based on the response surface methodology (RSM). The relationship between the proposed powdering quality index and the research variables was well expressed. An improved multi-objective optimization algorithm of the non-dominated sorting genetic algorithm II (NSGA-II) was used to optimize the powder laying quality of nylon powder in the SLS process. We provided different optimization schemes according to the different process requirements. The reliability of the multi-objective optimization results for powdering quality was verified via experiments.

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Dynamic investigation on the powder spreading during selective laser melting additive manufacturing

Cited by 38 publications

References 38 publications

Experimental Characterization and Computational Simulation of Powder Bed for Powder Bed Fusion Additive Manufacturing

Experimental Characterization and Computational Simulation of Powder Bed for Powder Bed Fusion Additive Manufacturing

The effects of locations on the build tray on the quality of specimens in powder bed additive manufacturing

Investigation of the Effects of Roller Spreading Parameters on Powder Bed Quality in Selective Laser Sintering

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