Date of Award

2015

Degree Type

Creative Project

Degree Name

Master of Science (MS)

Department

Mechanical and Aerospace Engineering

First Advisor

Ling Liu

Abstract

Metal 3D printing has caught the attention of many large industries. There have been stories of great success using metal 3D printing. Some of the largest industries to successfully use metal 3D printing are aerospace and medical. These industries have succeeded with metal 3D printing because of their need for light and complex parts. These success stories lead other industries to investigate how metal 3D printing or Direct Metal Laser Sintering (DMLS) can help them. Industries that are involved in high volume production ask how they can take advantage of the complexity and customization that is available with 3D printing. This report explores the feasibility of using metal 3D printing in high volume production applications.

There are many differences in 3D printed metal parts and parts made from traditional methods. The material properties of three DMLS materials are tested and compared to published values and wrought material in this report. Some of the material properties that are tested are: tensile strength, yield strength, Young’s modulus, elongation-at-break, toughness, hermeticity, and hardness. Hydroburst of thin walled vessel and microstructure are also examined.

The comparison of these properties shows that the tensile strength, yield strength, Young’s modulus, hardness and elongation-at-break for these three materials are the some order magnitude as wrought material and published values. They do vary from expected results in some cases but they have relatively tight groupings.

In most cases the toughness of DMLS parts is 1/3 that of the wrought material, except for in the case of the maraging steel, the toughness of the DMLS part is three times higher than the wrought material.

The hermeticity and hydroburst results for the DMLS parts are as would be expected from the wrought material.

This report explains the specific design techniques that should be followed to get advantage in 3D printed parts. These techniques include understanding build orientation to reduce support structure, reduce build time and to maximize the parts per build. The geometry of the part can be modified to change how the part deforms while it is being built. A minimum wall thickness of .5 mm is recommended because of this.

There is an advantage in using DMLS for complex tooling in high volume production. With DMLS the complexity of the part is free, so it is often advantageous to create complexity by combining parts, making custom parts or making the part smaller or lighter weight. As people start-using DMLS for tooling in high volume production, these advantages will become clearer. This leads to a new way of thinking. Designers will have freedom to design parts that have never been possible before.

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