Numerical Simulation of Extrusion Additive Manufacturing: Fused Deposition Modeling

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We demonstrate a 3D computational fluid dynamic (CFD) simulation of the Fused Deposition Modeling (FDM) process. Extrusion-based additive manufacturing technologies, such as FDM, are advancing rapidly as applications of rapid prototyping for finished product development and manufacturing proliferate. FDM, which is among the most widely used additive manufacturing techniques, is a layer by layer manufacturing technology that involves rapid phase change of the material, i.e. upon heating before extrusion and subsequent rapid cooling as it forms the desired structure [1]. This technology is very versatile and new applications are frequently reported. However, despite the widespread and growing use of FDM, relatively few rigorous process models exist and rational design for applications is lacking. Accurate numerical models that include a complete set of tunable parameters are required to obtain desired characteristics and quality of the finished printed structure. In this process, as the nozzle moves over the build platform to fabricate a pre-specified geometry, it deposits a thin thread of heated flowing material, which is extruded from a nozzle. The material solidifies quickly once deposited. Solid layers are created by following a horizontal movement where the extruded threads are deposited side-by-side inside an obtrusive boundary [1, 3]. 3D solid structures can be formed by either drop wise or continuous solidification. Among the desirable characteristics is the reduction of internal residual stresses due to uneven cooling of the part, as well as uniformity of extrusion velocity [2]. In this paper, we present a fully coupled thermo-fluidic computational model of the FDM printing process. The key tunable parameters taken into account in the simulation include the feed mechanism of the material, extruder nozzle dimensions, extruder angle and velocity with respect to the substrate, substrate temperature, extrusion velocity, and the residual stresses in the formed structure. This CFD model also takes into the account the heat flux and pressure drop estimation at the nozzle for smooth and desired successful bonding of the extruded material in the deposition process. In this presentation, we demonstrate the CFD model using the commercial program, FLOW3D (www.flow3d.com), for parametric analysis of the underlying physics for the FDM process.

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Journal: TechConnect Briefs
Volume: 4, Informatics, Electronics and Microsystems: TechConnect Briefs 2018
Published: May 13, 2018
Pages: 118 - 121
Industry sector: Advanced Materials & Manufacturing
Topic: 3D Printing
ISBN: 978-0-9988782-1-8