Powder deposition mechanism during powder spreading with different spreader geometries in powder bed fusion additive manufacturing
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.
About: This article is published in Powder Technology.The article was published on 2022-01-01. It has received 12 citations till now. The article focuses on the topics: Materials science & Deposition (geology).
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TL;DR: In this paper , the influence of the substrate surface topography on powder spreading performance over a set of realistic surfaces was investigated and it was found that a finer more cohesive powder can achieve the best layer coverage over realistic surfaces.
Abstract: Powder recoating is a key step in metal Additive Manufacturing (AM) processes where powder is spread across laser processed surfaces to add material for the next layer. Achieving the desired thin powder layers that are both sufficiently dense and uniform is essential for maintaining the requisite geometric tolerances and final part quality. In this study, we focus on the influence of the substrate surface topography by comparing spreading performance over a set of realistic surfaces. We simulate powder spreading over these surfaces using a calibrated non-spherical particle Discrete Element Model for Ti-6Al-4V that incorporates cohesion and Coulomb friction interactions between particles and surfaces. We identify the four key length scales of the recoating process determined by frictional contacts, powder size distribution, the layer thickness and the melted surface topography. We find that realistic AM surfaces show markedly different powder coverage compared to an idealised flat-plane. Rougher surfaces are found to be recoated with larger amounts of powder than smoother surfaces, as smaller particles get trapped by the grooves and valleys across the surface. Counterintuitively, we find that a finer more cohesive powder can achieve the best layer coverage over realistic surfaces - indicating that powder flowability is an incomplete measure of powder spreading performance on realistic AM surfaces. We also demonstrate how the recoating process can significantly size segregate the feedstock powder, favouring deposition of smaller sized particles on the melted surfaces.
7 citations
TL;DR: In this article , a review on multi-physics related to metal powder recoating and further melting and solidification process is presented, including model theory and validation, effects of process parameters, and physics of particle flow and size segregation.
4 citations
TL;DR: In this article , a review of powder spreading and spreadability in metal additive manufacturing is presented, focusing on the current progress in understanding spreading dynamics, the role of powder characteristics, the spreading systems and the testing tools developed for assessing powder spreadability.
4 citations
TL;DR: In this article , the physical characteristics of stoichiometric hydroxyapatite microspheres produced by spray-drying process through different operating conditions were evaluated by analysing the particle size, shape, moisture, and agglomerates strength.
3 citations
TL;DR: In this paper , a theoretical analysis of magnetic powder seal performance is given, and a determinant coefficient is put forward to measure the capacity of magnetometer-based magnetic powder sealing.
2 citations
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TL;DR: In this article, three parallel algorithms for classical molecular dynamics are presented, which can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors.
32,670 citations
TL;DR: The distinct element method as mentioned in this paper is a numerical model capable of describing the mechanical behavior of assemblies of discs and spheres and is based on the use of an explicit numerical scheme in which the interaction of the particles is monitored contact by contact and the motion of the objects modelled particle by particle.
Abstract: The distinct element method is a numerical model capable of describing the mechanical behaviour of assemblies of discs and spheres. The method is based on the use of an explicit numerical scheme in which the interaction of the particles is monitored contact by contact and the motion of the particles modelled particle by particle. The main features of the distinct element method are described. The method is validated by comparing force vector plots obtained from the computer program BALL with the corresponding plots obtained from a photoelastic analysis. The photoelastic analysis used for the comparison is the one applied to an assembly of discs by De Josselin de Jong and Verruijt (1969). The force vector diagrams obtained numerically closely resemble those obtained photoelastically. It is concluded from this comparison that the distinct element method and the program BALL are valid tools for research into the behaviour of granular assemblies. La methode des elements distincts est un modele numerique capab...
12,472 citations
Book•
01 Jan 2009
TL;DR: Gibson et al. as discussed by the authors presented a comprehensive overview of additive manufacturing technologies plus descriptions of support technologies like software systems and post-processing approaches, and provided systematic solutions for process selection and design for AM Additive Manufacturing Technologies: Rapid Prototyping to Direct Digital Manufacturing.
Abstract: Additive Manufacturing Technologies: Rapid Prototyping to Direct Digital Manufacturing deals with various aspects of joining materials to form parts. Additive Manufacturing (AM) is an automated technique for direct conversion of 3D CAD data into physical objects using a variety of approaches. Manufacturers have been using these technologies in order to reduce development cycle times and get their products to the market quicker, more cost effectively, and with added value due to the incorporation of customizable features. Realizing the potential of AM applications, a large number of processes have been developed allowing the use of various materials ranging from plastics to metals for product development. Authors Ian Gibson, David W. Rosen and Brent Stucker explain these issues, as well as: Providing a comprehensive overview of AM technologies plus descriptions of support technologies like software systems and post-processing approaches Discussing the wide variety of new and emerging applications like micro-scale AM, medical applications, direct write electronics and Direct Digital Manufacturing of end-use components Introducing systematic solutions for process selection and design for AM Additive Manufacturing Technologies: Rapid Prototyping to Direct Digital Manufacturing is the perfect book for researchers, students, practicing engineers, entrepreneurs, and manufacturing industry professionals interested in additive manufacturing.
3,087 citations
TL;DR: In this paper, the effect of the recoil pressure and Marangoni convection in laser powder bed fusion (L-PBF) of 316L stainless steel was demonstrated. And the results were validated against the experiments and the sensitivity to laser absorptivity was discussed.
1,649 citations
TL;DR: In this article, the societal impact of additive manufacturing from a technical perspective is reviewed, and an abundance of evidences are found to support the promises of additive-manufacturing in the following areas: (1) customized healthcare products to improve population health and quality of life, (2) reduced environmental impact for manufacturing sustainability, and (3) simplified supply chain to increase efficiency and responsiveness in demand fulfillment.
Abstract: Thirty years into its development, additive manufacturing has become a mainstream manufacturing process. Additive manufacturing build up parts by adding materials one layer at a time based on a computerized 3D solid model. It does not require the use of fixtures, cutting tools, coolants, and other auxiliary resources. It allows design optimization and the producing of customized parts on-demand. Its advantages over conventional manufacturing have captivated the imagination of the public, reflected in recent mainstream publications that call additive manufacturing “the third industrial revolution.” This paper reviews the societal impact of additive manufacturing from a technical perspective. Abundance of evidences were found to support the promises of additive manufacturing in the following areas: (1) customized healthcare products to improve population health and quality of life, (2) reduced environmental impact for manufacturing sustainability, and (3) simplified supply chain to increase efficiency and responsiveness in demand fulfillment. In the mean time, the review also identified the need for further research in the areas of life-cycle energy consumption evaluation and potential occupation hazard assessment for additive manufacturing.
1,440 citations