Numerical Modeling of Powder Gas Interaction for Laser Powder Bed Fusion Process

2020 ◽  
Author(s):  
Xuxiao Li ◽  
Wenda Tan
Keyword(s):  
Flow Field ◽  
Gas Flow ◽  
Driving Forces ◽  
Current Model ◽  
Quantitative Information ◽  
Powder Bed Fusion ◽  
Metal Powders ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Free Jet

Abstract The powder motion induced by the gas flow has been identified as one of the critical phenomena in laser powder bed fusion processes that significantly affects the build quality. However, the gas dynamics and its induced driving forces for the powder motions have not been well quantified. A numerical model is developed to investigate such powder-gas interactions. With a combination of computational fluid dynamics and particle tracking techniques, the model is capable of simulating the transient gas flow field surrounding the powder and the forces exerted on powder surfaces. The interaction between metal powders and a free jet is investigated with the current model. In the simulation results, the entrainment and the ejection motions of powders with respect to the free jet can be predicted. It is found that the driving forces of these motions are majorly contributed by the pressure differences in the gas flow surrounding the powder, and the powders can also interact with the jet to significantly alter the flow field. Quantities which are difficult to measure by experiments are quantified by the simulations, such as the velocity and pressure field in the gas, as well as the subjected forces and torques of powders. Such quantitative information provides insights to the mechanisms of the powder-gas interaction in laser powder bed fusion processes.

Numerical Modeling of Powder Gas Interaction Relative to Laser Powder Bed Fusion Process

2020 ◽  
Vol 143 (5) ◽  
Author(s):  
Xuxiao Li ◽  
Wenda Tan
Keyword(s):  
Flow Field ◽  
Gas Flow ◽  
Driving Forces ◽  
Current Model ◽  
Quantitative Information ◽  
Powder Bed Fusion ◽  
Metal Powders ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Free Jet

Abstract The powder motion induced by the gas flow has been identified as one of the critical phenomena in laser powder bed fusion processes that significantly affect the build quality. However, the gas dynamics and its induced driving forces for the powder motions have not been well quantified. A numerical model is developed to investigate such powder-gas interactions. With a combination of computational fluid dynamics and particle tracking techniques, the model is capable of simulating the transient gas flow field surrounding the powder and the forces exerted on powder surfaces. The interaction between metal powders and a free jet is investigated with the current model. In the simulation results, the entrainment and the ejection motions of powders with respect to the free jet can be predicted. It is found that the driving forces of these motions are majorly contributed by the pressure differences in the gas flow surrounding the powder, and the powders can also interact with the jet to significantly alter the flow field. Quantities that are difficult to measure by experiments are quantified by the simulations, such as the velocity/pressure fields in the gas as well as the subjected forces and torques on powders. Such quantitative information provides insights about the mechanisms of the powder-gas interaction in laser powder bed fusion processes.

scholarly journals Influence of Laser Energy Input and Shielding Gas Flow on Evaporation Fume during Laser Powder Bed Fusion of Zn Metal

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2677
Author(s):  
Yu Qin ◽  
Jinge Liu ◽  
Yanzhe Chen ◽  
Peng Wen ◽  
Yufeng Zheng ◽  
...  
Keyword(s):  
Energy Input ◽  
Gas Flow ◽  
Evaporation Rate ◽  
Laser Energy ◽  
Circulation System ◽  
Powder Bed Fusion ◽  
Shielding Gas ◽  
Laser Powder Bed Fusion ◽  
Conservation Of Energy ◽  
Powder Bed

Laser powder bed fusion (LPBF) of Zn-based metals exhibits prominent advantages to produce customized biodegradable implants. However, massive evaporation occurs during laser melting of Zn so that it becomes a critical issue to modulate laser energy input and gas shielding conditions to eliminate the negative effect of evaporation fume during the LPBF process. In this research, two numerical models were established to simulate the interaction between the scanning laser and Zn metal as well as the interaction between the shielding gas flow and the evaporation fume, respectively. The first model predicted the evaporation rate under different laser energy input by taking the effect of evaporation on the conservation of energy, momentum, and mass into consideration. With the evaporation rate as the input, the second model predicted the elimination effect of evaporation fume under different conditions of shielding gas flow by taking the effect of the gas circulation system including geometrical design and flow rate. In the case involving an adequate laser energy input and an optimized shielding gas flow, the evaporation fume was efficiently removed from the processing chamber during the LPBF process. Furthermore, the influence of evaporation on surface quality densification was discussed by comparing LPBF of pure Zn and a Titanium alloy. The established numerical analysis not only helps to find the adequate laser energy input and the optimized shielding gas flow for the LPBF of Zn based metal, but is also beneficial to understand the influence of evaporation on the LPBF process.

scholarly journals Coated Metal Powders for Laser Powder Bed Fusion (L-PBF) Processing: A Review

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1831
Author(s):  
Robert Bidulsky ◽  
Federico Simone Gobber ◽  
Jana Bidulska ◽  
Marta Ceroni ◽  
Tibor Kvackaj ◽  
...  
Keyword(s):  
Physical Properties ◽  
Powder Bed Fusion ◽  
Metal Powders ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
The Past ◽  
Coated Metal ◽  
Mechanical And Physical Properties ◽  
Interesting Approach ◽  
Coating Methods

In the last years, functionalized powders are becoming of increasing interest in additive manufacturing (particularly in laser powder bed fusion processing, L-PBF), due to their improved flowability and enhanced processability, particularly in terms of laser absorbance. Functionalized powders may also provide higher final mechanical or physical properties in the manufactured parts, like an increased hardness, a higher tensile strength, and density levels close to theoretical. Coatings represent a possible interesting approach for powders’ functionalizing. Different coating methods have been studied in the past years, either mechanical or non-mechanical. This work aims to present an overview of the currently obtained coated powders, analyzing in detail the processes adopted for their production, the processability of the coated systems, and the mechanical and physical properties of the final parts obtained by using L-PBF for the powders processing.

scholarly journals Influence of Gas Flow Speed on Laser Plume Attenuation and Powder Bed Particle Pickup in Laser Powder Bed Fusion

JOM ◽  
2020 ◽  
Vol 72 (3) ◽  
pp. 1039-1051
Author(s):  
Haopeng Shen ◽  
Paul Rometsch ◽  
Xinhua Wu ◽  
Aijun Huang
Keyword(s):  
Gas Flow ◽  
Flow Speed ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Laser Plume ◽  
Powder Bed

On Characterizing Uncertainty Sources in Laser Powder Bed Fusion Additive Manufacturing Models

2021 ◽  
Author(s):  
Tesfaye Moges ◽  
Kevontrez Jones ◽  
Shaw Feng ◽  
Paul Witherell ◽  
Gaurav Ameta
Keyword(s):  
Additive Manufacturing ◽  
Computational Models ◽  
Predictive Accuracy ◽  
Powder Bed Fusion ◽  
Metal Powders ◽  
Laser Powder Bed Fusion ◽  
Powder Morphology ◽  
Powder Bed ◽  
Uncertainty Sources ◽  
Ontology Language

Abstract Tremendous efforts have been made to use computational models of, and simulation models of, Additive Manufacturing (AM) processes. The goals of these efforts are to better understand process complexities and to realize better, high-quality parts. However, understanding whether any model is a correct representation for a given scenario is a difficult proposition. For example, when using metal powders, the laser powder bed fusion (L-PBF) process involves complex physical phenomena such as powder morphology, heat transfer, phase transformation, and fluid flow. Models based on these phenomena will possess different degrees of fidelity since they often rely on assumptions that may neglect or simplify process physics, resulting in uncertainties in their prediction accuracy. Predictive accuracy and its characterization can vary greatly between models due to their uncertainties. This paper characterizes several sources of L-PBF model uncertainty for low, medium, and high-fidelity thermal models including modeling assumptions (model-form uncertainty), numerical approximations (numerical uncertainty), and input parameters (parameter uncertainty). This paper focuses on the input uncertainty sources, which we model in terms of a probability density function (PDF), and its propagation through all other L-PBF models. We represent uncertainty sources using the Web Ontology Language (OWL), which allows us to capture the relevant knowledge used for interoperability and reusability. The topology and mapping of the uncertainty sources establish fundamental requirements for measuring model fidelity and for guiding the selection of a model suitable for its intended purpose.

scholarly journals On the effect of shielding gas flow on porosity and melt pool geometry in laser powder bed fusion additive manufacturing

2020 ◽  
Vol 32 ◽  
pp. 101030 ◽  
Author(s):  
Joni Reijonen ◽  
Alejandro Revuelta ◽  
Tuomas Riipinen ◽  
Kimmo Ruusuvuori ◽  
Pasi Puukko
Keyword(s):  
Additive Manufacturing ◽  
Gas Flow ◽  
Powder Bed Fusion ◽  
Shielding Gas ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Melt Pool

scholarly journals Inert Gas Flow Speed Measurements in Laser Powder Bed Fusion Additive Manufacturing

2021 ◽  
Author(s):  
Jordan S. Weaver ◽  
Alec Schlenoff ◽  
David C. Deisenroth ◽  
Shawn P. Moylan
Keyword(s):  
Additive Manufacturing ◽  
Gas Flow ◽  
Flow Speed ◽  
Inert Gas ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed
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