Session: 16-01-01: Government Agency Student Poster Competition

Paper Number: 150694

150694 - Can We 3d Print 100% Dense Copper? a Process Parameter Study for Metal Fused Filament Fabrication 

Metal Fused Filament Fabrication (mFFF) is an increasingly popular Additive Manufacturing technology that allows for the efficient production of complex metal geometry while reducing cost and waste. Parts can be printed with metal filament to maintain the material properties and reliability of metal while creating the possibility for complex internal structures. The mFFF process consists of three major steps: Printing, Debinding, and Sintering. Printing consists of additively extruding layers of filament to create the desired geometry with a fixed set of printing parameters. Debinding uses heat to remove the binding material to leave only the desired metal, and this step leaves the part brittle due to the gaps left from the removal of the polymer binder. Finally, a part must be sintered when heat is used to fuse the remaining metal particles together to form a solid part. While mFFF prevails as a promising production method, there are a lot of process variations being propagated across the steps, due to the complex manufacturing process chain. Within all the inherit defects, internal porosity is the most important type, since the porosity significantly weakens a part creating small internal stress concentrations throughout. This leads to the major limitation of mFFF when compared to its traditional counterparts, especially for mission-critical applications.

The objective of this research is to understand the effects of printing process parameters on the internal porosity patterns of a mFFF copper print. The parameters chosen are Layer Height (The height between layers of extruded material), Extrusion Width (The width of the internal struts extruded), and Extrusion Multiplier (The rate at which the material is extruded). A full factorial design was used with three centerpoint control runs added. Therefore, 11 specimens were printed, debinded, and sintered. X-ray Computed Tomography (Xray CT) is utilized to analyze the internal structure of the mFFF copper parts before and after both debinding and sintering process. Subsequently, a porosity algorithm was used to identify and characterize the internal porosities. Descriptive features of each pore (e.g., XYZ coordinates, probability, sphericity, radius) can be extracted. The analysis of the experimental data is two-folded. First, the porosity distribution patterns were evaluated and the effects of printing parameter on the porosity distribution were examined. This facilitates printing process parameter optimization for mFFF. Secondly, the growing trajectory of the internal pores were analyzed to elucidate different porosity growth patterns in the debinding and sintering stages of mFFF. The results will enable internal structure prediction, facilitating in-situ decision making for process adjustment and control in mFFF processes. Future work will include investigation into the effects of the porosity patterns on the thermal and electrical properties of the material fabricated by mFFF.

Presenting Author: Zac Leblanc Mississippi State University

Presenting Author Biography: I am a senior mechanical engineering undergrad student at Mississippi State University where I work as an undergraduate research assistant in the industrial and systems department. My research focuses on metal fused filament fabrication specifically with copper. Outside of school I enjoy fishing, being outdoors, playing with my dog, and most importantly cooking. After I graduate, I plan to use my degree to begin work in the space industry.

Authors:

Zac Leblanc Mississippi State University
Wenmeng Tian Mississippi State University
Jian Zhao Mississippi State University