Abstract
Material extrusion (MEX) processes that employ metal-polymer composites to 3D print “green” parts offer an economical and user-friendly alternative to melt-based additive manufacturing. Leveraging existing powder metallurgy knowledge permits the fabrication of functional parts with predictable microstructures and properties. However, the large fractions of binder, typically 45 to 55 vol%, introduce the need for specialized debinding procedures that significantly prolong the total manufacturing time, limit geometrical capabilities, and negatively affect mechanical properties if not adequately removed. To address these limitations, this paper presents a MEX framework that involves (1) synthesis of a 316L stainless steel paste with just 3.2 vol% binder, (2) design and implementation of a synchronized two-stage extrusion mechanism, (3) an experimentally-driven approach to evaluate the effects of MEX parameters on extrudate morphology, density, and surface roughness, (4) multi-objective optimization, and (5) evaluation of thermal post-processing strategies. The as-printed samples displayed densities of 4.67 g/cm3 and 21.54 μm areal surface roughness. The framework permitted the fabrication of increasingly complex geometries and sintered densities measuring 91.8–97.9%TD after just 22 h of thermal post-processing (including approx. ten hours of cooling time in the furnace).
| Original language | English |
|---|---|
| Pages (from-to) | 238-251 |
| Number of pages | 14 |
| Journal | Journal of Manufacturing Processes |
| Volume | 108 |
| DOIs | |
| State | Published - Dec 22 2023 |
| Externally published | Yes |
Funding
The authors gratefully acknowledge NASA's, United States support under grant number 80NSSC19K1052. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of NASA. The authors would like to thank Dr. James Paramore for the helpful discussions about the SS316L thermal treatments and for providing access to the sintering furnace, and the Texas A&M University Materials Characterization Core Facility (RRID:SCR_022202) for providing access to the SEM equipment. The authors gratefully acknowledge NASA’s, United States support under grant number 80NSSC19K1052 . Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of NASA. The authors would like to thank Dr. James Paramore for the helpful discussions about the SS316L thermal treatments and for providing access to the sintering furnace, and the Texas A&M University Materials Characterization Core Facility (RRID:SCR_022202) for providing access to the SEM equipment.
| Funders | Funder number |
|---|---|
| National Aeronautics and Space Administration | 80NSSC19K1052 |
| Texas A and M University | SCR_022202 |
Keywords
- 316L stainless steel
- Additive manufacturing
- Direct ink writing
- Material extrusion
- Robocasting
