Date on Master's Thesis/Doctoral Dissertation

12-2013

Document Type

Doctoral Dissertation

Degree Name

Ph. D.

Department

Industrial Engineering

Degree Program

Industrial Engineering, PhD

Committee Chair

Stucker, Brent E.

Committee Co-Chair (if applicable)

Gebhardt, Andreas

Committee Member

Gebhardt, Andreas

Committee Member

DePuy, Gail W.

Committee Member

Starr, Thomas

Subject

Lasers--Industrial applications; Silver

Abstract

Selective Laser Melting (SLM) is a growing technology for the additive manufacturing of parts and structures. Based on a powder layer technique, a laser locally melts the powder and forms new structures. [1] In this approach, silver-based alloy powders will be used. The processing of this kind of material is considered difficult compared to other powder materials such as mild steels or tool steels. Silver powder is a highly reflecting material and has excellent thermal conductivity. Both properties make it difficult to process using Selective Laser Melting. Due to its high price, industries use silver parts as economically as possible so that the parts tend to be thin and light weight. Therefore, one limiting constraint should be the manufacturing of thin, hollow parts. The second constraint is the usage of a laser with small power output. The reasons why this machine will be used is that it is affordable for a large amount of companies, that it can be placed nearly everywhere and that it economically beats large workshops with cast and milling facilities. Since AgCu7 is a typical artwork material and AgCu28 is a typical technical material, this work is related to further research on the processing of both materials. Processing maps were developed using the response surface method. The dissertation covers the questions why silver is used, what was done, which methods are available to answer upcoming questions and which solutions are proposed. Chapter one provides an introduction to the topic. Chapter two covers information that is available about different precious materials, physical relations and other aspects that are necessary to understand what happens in the melt pool. Chapter three deals with important parameters and collects some fundamental approaches to uncover new relations. Chapter four shows the pretests, powder distributions, absorptivity measurements, and necessary steps to manufacture hollow structures. In chapter five, six, and seven the experiments for AgCu7 and AgCu28 are described. Factorial designs and the response surface method were used in order to analyze the dependency of process parameters on porosity. In chapter eight, the results of the materials are compared. Chapter nine presents the summary and future perspectives.

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