MA04.11.03 : Improving Properties in Polymer Sintering Through Large Area Projection Sintering

5:00 PM–7:00 PM Apr 5, 2018 (America - Denver)

PCC North, 300 Level, Exhibit Hall C-E

Justin Nussbaum1 Nathan Crane1

1, University of South Florida, Tampa, Florida, United States

Additive manufacturing (AM) is rapidly advancing due to the large demand for custom parts, quick turnaround times and/or components with complex geometries. In AM, a 3D model is sliced into a series of 2D cross sections. 3D Components are formed by fusing material in the shape of each cross section. This process repeats as each layer is stacked on-top of each other to form the 3D model. One dominant technique, laser sintering (LS) utilizes a laser to heat and fuse thermoplastic powder together. Laser scanning requires fast traverse speeds and high heating rates in order to economically bond the materials. However, the resulting temperature gradients and short processing time (<1 ms) limit the materials that can be sintered and the properties that are achieved. A new AM technology, Large Area Projection Sintering (LAPS), creates parts by fusing an entire layer of material simultaneously. By fusing an entire layer, longer exposure times can be employed without compromising overall build time. This allows for significantly lower peak temperatures (and thus less degradation) and allows more time for the material to densify. For example, Peak surface temperatures in LAPS are less than 20 C above preheat temperature compared to over 100 C reported for LS. This work reports on the sintering kinetics of the most common LS material: polyamide 12 (PA12). The results of processing at longer times (~1-10s) using the LAPS process are compared to similar materials processed with commercial sintering equipment. LAPS is shown to more fully melt the powder than LS.. It also maintains or improves on LS strength while significantly increasing ductility. Thissuggests that projection sintering could open the door to processing new materials with greater temperature sensitivity and increased opportunities for spatial control over sintered properties.