Abstract
Large format additive manufacturing (LFAM) necessitates the use of short fiber thermoplastic composites, such as carbon fiber filled acrylonitrile butadiene styrene, to enable printing. Currently, when LFAM parts are machined into their final shape, the machining scrap (i.e., small flake like particles and offcuts) is landfilled. Previous studies have demonstrated the viability of recycling end-of-life LFAM parts by shredding and optionally re-compounding the material back into pellets. However, there is little understanding of the value and performance of recycled material made from LFAM machining scrap, which if pursued could motivate more broad recycling of this waste stream. In this study, recycled in-process machining scrap is explored as an LFAM feedstock source. Herein, it is found that the primary degradation mechanism of the recycled material is significant fiber length attrition during surface machining. While this fiber attrition negatively impacts the mechanical performance of the material in the print direction, it seems that the changes in processing behaviors and print quality, namely the surface roughness of the printed structure associated with shorter fiber lengths, is beneficial to interlayer adhesion. The tensile strength and elastic modulus of the recycled material, in the print direction, decreased 11% and 31% respectively compared to the pristine material. However, in the layer-wise direction it was found that the recycled material exhibited no significant change in elastic modulus and a significant 21% increase in tensile strength – a surprising result. This work indicates that machining waste could be a viable material stream for recycled LFAM feedstock materials.
| Original language | English |
|---|---|
| Article number | 111291 |
| Journal | Composites Part B: Engineering |
| Volume | 275 |
| DOIs | |
| State | Published - Apr 15 2024 |
Funding
The US Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Advanced Materials and Manufacturing Office provided support for this work under CPS Agreement 35863. The authors would like to acknowledge the Sustainable Materials and Manufacturing Alliance for Renewable Technologies Consortium, as well as the Manufacturing Demonstration Facility of Oak Ridge National Laboratory. The authors would also like to thank Techmer PM for providing material and completing the compounding of the collected materials for recycling. The authors would like to thank Jake Dvorak and the University of Tennessee MABE Maker Lab for assisting in machining and sample preparation. The authors would like to thank the following people and research groups for access to equipment and assistance in sample preparation: Evan Holt and the Kilbey Lab at the University of Tennessee, Matthew Roach and Dr. Bradley Jared at the University of Tennessee, Sarah Graham at Oak Ridge National Laboratory, and Ally Collier and Nina Bhat from the PCAM Lab at the University of Tennessee. The US Department of Energy (DOE) , Office of Energy Efficiency and Renewable Energy , Advanced Materials and Manufacturing Office provided support for this work under CPS Agreement 35863. The authors would like to acknowledge the Sustainable Materials and Manufacturing Alliance for Renewable Technologies Consortium, as well as the Manufacturing Demonstration Facility of Oak Ridge National Laboratory. The authors would also like to thank Techmer PM for providing material and completing the compounding of the collected materials for recycling. The authors would like to thank Jake Dvorak and the University of Tennessee MABE Maker Lab for assisting in machining and sample preparation. The authors would like to thank the following people and research groups for access to equipment and assistance in sample preparation: Evan Holt and the Kilbey Lab at the University of Tennessee, Matthew Roach and Dr. Bradley Jared at the University of Tennessee, Sarah Graham at Oak Ridge National Laboratory, and Ally Collier and Nina Bhat from the PCAM Lab at the University of Tennessee.
| Funders | Funder number |
|---|---|
| Advanced Materials and Manufacturing Office | 35863 |
| Sustainable Materials and Manufacturing Alliance for Renewable Technologies Consortium | |
| U.S. Department of Energy | |
| Office of Energy Efficiency and Renewable Energy | |
| Oak Ridge National Laboratory | |
| University of Tennessee |
