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5 results on '"Valerio Lampitella"'

1. Discrete Element Method Analysis of the Spreading Mechanism and Its Influence on Powder Bed Characteristics in Additive Manufacturing

Author

Valerio Lampitella, Marco Trofa, Antonello Astarita, and Gaetano D’Avino

Subjects
discrete element method, spreading process, additive manufacturing, Mechanical engineering and machinery, TJ1-1570
Abstract

Laser powder bed fusion additive manufacturing is among the most used industrial processes, allowing for the production of customizable and geometrically complex parts at relatively low cost. Although different aspects of the powder spreading process have been investigated, questions remain on the process repeatability on the actual beam–powder bed interaction. Given the influence of the formed bed on the quality of the final part, understanding the spreading mechanism is crucial for process optimization. In this work, a Discrete Element Method (DEM) model of the spreading process is adopted to investigate the spreading process and underline the physical phenomena occurring. With parameters validated through ad hoc experiments, two spreading velocities, accounting for two different flow regimes, are simulated. The powder distribution in both the accumulation and deposition zone is investigated. Attention is placed on how density, effective layer thickness, and particle size distribution vary throughout the powder bed. The physical mechanism leading to the observed characteristics is discussed, effectively defining the window for the process parameters.

Published
2021
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4. Powder Bed Spreading in Additive Manufacturing: Numerical Simulations and Experimental Study

Author

Gaetano D'Avino, Antonello Astarita, Marco Trofa, Valerio Lampitella, Lampitella, V., Trofa, M., Astarita, A., and Davino, G.

Subjects
Computer simulation, business.industry, Computer science, Powder bed, Computation, Process (computing), Discrete element method, Manufacturing, Deposition (phase transition), Additive, Process engineering, business, Focus (optics), Energy source, Recoating, Simulation
Abstract

Powder bed based additive manufacturing technologies allow for the production of more complex parts with overall better characteristics and are therefore of high industrial interest. However, due to an incomplete understanding of the multi-physic processes involved there are still some issues to be addressed. More specifically, in this work we will focus on the powder spreading stage. In powder bed-based technologies a thin layer of powder is deposited by a recoating device and is then processed by an energy source to obtain a layer of the final part. We use a numerical model based on the Discrete Element Method to reproduce the spreading process and propose an experimental analysis procedure to obtain data suitable for the validation of such numerical model. The experiments are carried out on a purposely designed device and both computations and experiment are referred to a single layer deposition. Being able to validate the numerical results can give way to a more confident use of DEM based models for the optimization of the spreading process and therefore improve the quality of printed parts. (Abstract)

Published
2021
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5. Spreading of powders in powder bed additive manufacturing: An experimental approach

Author

Marco Trofa, Valerio Lampitella, Gaetano D'Avino, Antonello Astarita, Lampitella, V., Trofa, M., Astarita, A., and D'Avino, G.

Subjects
Fusion, Work (thermodynamics), Materials science, business.industry, Additive manufacturing, Powder bed, Process (computing), Raw material, Experimental, Laser powder bed fusion, Deposition (phase transition), Process engineering, business, Layer (electronics), Laser beams
Abstract

Powder bed additive manufacturing allows for the production of fully customizable parts and is of great interest for industrial applications. However, the repeatability of the parts and the uniformity of the mechanical properties are still an issue. More specifically, the physical mechanism of the spreading process of the powders, which significantly affects the characteristics of the final part, is not completely understood. In powder bed fusion technologies, the spreading is performed by a device, typically a roller or a blade, that collects the powders from the feedstock and successively deposits them in a layer of several dozens of microns that is then processed with a laser beam. In this work, an experimental approach is developed and employed to study the powder spreading process and analyze in detail the motion of the powders from the accumulation zone to the deposition stage. The presented experiments are carried out on a home-made device that reproduces the spreading process and enables the measurement of the characteristics of the powder bed. Furthermore, the correlation with the process parameters, e.g., the speed of the spreading device, is also investigated. These results can be used to obtain useful insights on the optimal window for the process parameters.

Published
2021

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