Publication Date

2019

Document Type

Dissertation/Thesis

First Advisor

Sciammarella, Federico M.

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Mechanical Engineering

Abstract

In order to capitalize on the cost effectiveness of Metal Additive Manufacturing (MAM) it is critical to understand how to build components with consistency and high quality. Directed Energy Deposition (DED) is a MAM method for creating parts layer by layer through the use of a moving heat source and powder material inserted into the melt pool generated on the substrate. DED like most MAM processes are highly complex due to the rapid thermal gradients experienced during processing. These thermal gradients are determined by a variety of processing parameters which include laser power, powder feed rate, travel speed, layer height hatch spacing etc... A lot of effort has been carried out in the AM community to try and find what these critical parameters are and how they influence the thermal gradients. Despite all these ongoing efforts, many times in industry MAM part development will go through many iterations to find the right set of parameters to produce a quality part within tolerances. This is time consuming and not cost effective use of the MAM technology. Research carried out in the ARMM lab has established an experimental relationship between the ratio of the travel speed and powder flow at various power levels indicating good repeatability for 316L. The aim of this thesis is to reduce the amount of experimental data and combine numerical analysis to help optimize this relationship further. A 2D model was developed using COMSOL. The model solves the energy, momentum, and mass balance equations. Clad generation is simulated using moving mesh. This model was used to investigate this ratio and its effect on clad geometry and dilution. The model was validated experimentally with an OPTOMEC 850M LENS ran with 316L SS powder. Dilution of less than 50% was found for various energy densities above a ratio 0.3 g/in. This model lays the foundation of further investigation of selection of powder feed rate that results in ideal clad geometry.

Extent

66 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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