A Fluid-Dynamic Numerical Model for the Selective Laser Melting of High-Thickness Metallic Layers

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Cordovilla Baró, Francisco;  Garzón, Miguel;  Muñoz, Diego Alejandro;  Diaz, Javier;  García Beltrán, Angel  and  Ocaña Moreno, Jose Luis  (2017).  A Fluid-Dynamic Numerical Model for the Selective Laser Melting of High-Thickness Metallic Layers. In: "LiM 2017 International conference on Lasers in Manufacturing", 26 / 29.06.2017, Munich - Germany. pp. 1-10. ​

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The productivity in the selective laser melting (SLM) process is directly related to the thickness of the powder bed that is applied repeatedly, in each increment, in the growth of the consolidated material in the additive manufacturing process. Although most of the relevant phenomena (limited diffusivity associated with particle contact, phase changes, surface tension gradients associated with Marangoni convection, or even back pressure) are considered in models with small bed thicknesses (approximately 20 μm and  40 μm), in the case of large thicknesses (between 100 μm and 200 μm) these factors strongly influence the size and shape of the melt pool, which leads to a non-trivial geometry of the consolidated material.

The present work proposes the use of the arbitrary Lagrangean-Eulerian method (ALE method) to solve the thermal and Navier-Stokes equations in the framework of a free-motion discretization to simultaneously predict the evolution of space-time temperature and dynamics. associated melting bath. It allows to use a continuous domain to represent the powder bed, which, instead of a particle model approach, is advantageously compatible with realistic process parameters, where the laser covers long trajectories. The model was validated with experimental data using Inconel as work material, showing a good degree of fit.

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