Date of Award

12-2007

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Mechanical Engineering

Advisor

Angstadt, David C

Committee Member

Summers , Joshua D

Committee Member

Huang , Yong

Abstract

Solid freeform fabrication (SFF) technology has shown a great deal of promise for the plastic injection molding industry due to its ability to produce complex geometry tooling relatively quickly. However, one shortcoming of metal-based SFF processes is that they have difficulty producing parts with acceptable surface quality. As such, secondary operations, such as machining, are frequently required thereby increasing fabrication time and cost. In addition, there is variation in the surface quality that is dependent upon the surface orientation during the build process. For example, parts produced using the metal-based 3-D printing process have vertical faces with a typical roughness 50% greater than the horizontal faces.
This work investigates surface finish improvement techniques used with 3D printed metal parts during the infiltration treatment. The goal is to produce injection mold tooling with an acceptable surface quality without performing a secondary machining process. By extending the infiltration cycle and applying a planar contact surface to the face of a sample, reductions in roughness of up to 83% were achieved. Such a surface would be categorized as a D-series surface under the surface finish standards for injection molding. The optimal condition for roughness reduction is to use a horizontally oriented printed face with a polished quartz blank applied during an extended infiltration cycle. This study determined that the use of contact pressure does not have a clear and significant effect on roughness.

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