Capillary pressure and saturation of pore-controlled granules for powder bed binder jetting

Chun, Seung-Yeop; Kim, Tae-Wook; Ye, Bora; Jeong, Bora; Lee, Myeung-jin; Lee, Jun Young; Kim, Eok-Soo; Lee, Heesoo; Kim, Hong-Dae

doi:10.1016/j.apsusc.2020.145979

Cited by 15 publications

(6 citation statements)

References 39 publications

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“…In addition, the powder can be optimized for special applications. Since prior studies showed the influence of the grain surface and shape [ 18 ] on binder infiltration, future advancements in the simulation setup should include the implementation of realistic grain morphologies. Due to the high impact of the local particle structure, investigations on a higher number of representative RVE structures and alternative binder jetting parameters will be of further interest.…”

Section: Resultsmentioning

confidence: 99%

“…[ 16 ] The small droplets in inkjet printing make dynamic studies of droplet infiltration challenging. [ 17 ] Experimental studies generally investigate binder infiltration on larger droplet sizes [ 18 ] due to the simpler observation of the infiltration with optical methods. To allow for obtaining subsurface information with high spatial and temporal resolution, Parab et al used a high‐speed synchrotron X‐ray imaging technique to observe the binder jetting process in real time.…”

Section: Introductionmentioning

confidence: 99%

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Simulation of Binder Infiltration in Additive Manufacturing of Sand Molds

Erhard,

Tanjavooru,

Hartmann

et al. 2023

Adv Eng Mater

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This article proposes a CFD approach to simulate binder infiltration in 3D printing of sand molds using OpenFOAM facilitating the identification of suitable levers for application‐specific material and process developments. A method for randomly generating powder bulks of designated powder size distributions (PSD) and procedures for automated analysis of the infiltration profile and volume are introduced. Simulation is utilized to investigate binder infiltration using different droplet spacings, representing different printheads’ resolutions. The apparent particle size at the exact location of the droplets’ impact, the droplets’ landing position in relation to the respective surface topography, and thus the statistical appearance of particle formations appear to be influencing the infiltration profile. High‐speed camera observations show the plausibility of the predicted infiltration kinetics. An exemplary use case compares the predicted infiltration profiles to the compressive strength of specimens printed from silica sand with low binder contents. Simulation predicts an average infiltration of 250 µm that presumably achieves reliable bonding for layer thicknesses up to 365 µm. A decrease in strength with increasing layer thickness at constant binder contents can be found in the experiment – at layer thicknesses above 350 µm, only minor strengths are achieved.This article is protected by copyright. All rights reserved.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Simulation of Binder Infiltration in Additive Manufacturing of Sand Molds

Erhard,

Tanjavooru,

Hartmann

et al. 2023

Adv Eng Mater

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“…Powder beds of 316L stainless steel were prepared in fabricated aluminum well plates, designed to separate replicates and have a smooth, level surface to facilitate imaging. The powder was poured into each well, gently tapped, and leveled, thus simulating powder deposition in a binder jetting production process. , Trials to compare wells prepared using this method against compacted beds (tapped and compressed with a glass rod) resulted in a variation in absorption times on the order of ±10% between methods, an error similar to the variability between replicates under either preparation method.…”

Section: Methodsmentioning

confidence: 99%

“…A significant limitation in developing a BJP process is the selection of printing parameters for a particular binder and powder. Many studies in this area have focused on the equilibrium saturation of the binder in a powder, with particular emphasis on the effect of granule size. − Studies in adjacent fields, such as wet granulation in pharmaceuticals or soil hydrology in civil engineering, have also contributed to understanding the equilibrium state of powder–binder composites. − Developments in the study of BJP contribute to this wider context of fluid infiltration of porous media. Additionally, advances in BJP support progress in many fields, such as tissue engineering, microelectronics, and pharmaceuticals. − …”

Section: Introductionmentioning

confidence: 99%

Physicochemical Limitations of Capillary Models Applied to High-Concentration Polymer Solutions

et al. 2022

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Advances in binder jet printing (BJP) require the development of new binder–powder systems, for example, to increase compatibility with better performance metal alloys or to increase the strength of parts using stronger binders. The dynamics of binder absorption are principally understood through capillary models. However, validation of these models in BJP has focused on variation of powder properties. Using a design-of-experiments approach and an optical observation method to track absorption of droplets, this study tests the influence of fluid properties on absorption time against the predictions of capillary models. Properties specific to polymeric binders, such as molecular weight and entanglement state, are also considered. Capillary models are found to be generally accurate in predicting absorption time in dilute systems; however, these predictions are not accurate for highly concentrated binder solutions. The effect of polymer entanglement becomes prevalent as the solution concentration increases, which can also potentially occur as a result of increased evaporation due to powder bed heating. Specifically, concentrated solutions close to the onset of entanglement will absorb much more slowly than predicted. Future models of BJP systems must account for the possibility of polymer entanglement throughout the absorption process. Improved models will provide a more accurate understanding of the flow and solidification of the binder in the powder, allowing faster development of new binders for improved performance in printing.

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“…In a previous study, the droplet absorption time of the material on the layered surface in powder bed 3D printing was considered as an important parameter in evaluating the recoating possibility [20]. Therefore, in the 3D printing process, it is necessary to optimize the time taken by a droplet to fall on the powder interface and get absorbed [17].…”

Section: Powder Bed Property Evaluationmentioning

confidence: 99%

De-Powdering Effect of Foundry Sand for Cement Casting

et al. 2021

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With the development of the powder bed 3D printing process, sand casting can be performed with methods that are more advanced than the traditional ones, thus enabling new research on applied materials. When sand is 3D-printed with cement as a binder, its casting performance is improved and sufficient thermal stability of conventional organic and inorganic binders is ensured. In this study, to ensure high resolution and strength in a physical and simple mixture of cement and sand, the compatibility for casting was confirmed using submicron-level cement with ingredients and sizes similar to commercial sand, which is uniformly controlled at 4 µm, instead of conventional sand. To enable quick 3D printing, calcium aluminate cement, which has quick binding properties, was used for high-temperature casting. The strength up to 6 h after hydration was compared to determine the curing rate of silica, mullite, and alumina sand containing cement components. By investigating the change in strength due to heat treatment and comparing the adhesion drop test results after powder bed formation, the material containing silica sand was determined as the most suitable for powder layer 3D printing for application to the mold.

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Capillary pressure and saturation of pore-controlled granules for powder bed binder jetting

Cited by 15 publications

References 39 publications

Simulation of Binder Infiltration in Additive Manufacturing of Sand Molds

Simulation of Binder Infiltration in Additive Manufacturing of Sand Molds

Physicochemical Limitations of Capillary Models Applied to High-Concentration Polymer Solutions

De-Powdering Effect of Foundry Sand for Cement Casting

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