Paper Number
VP11 

Session
Pre-recorded Flash Presentations (virtual)

Title
Extrudate instabilities in fused filament fabrication additive manufacturing

Presentation Date and Time
All Week (Asynchronous) Any Time

Track / Room
Pre-recorded Presentation / Virtual

Authors (Click on name to view author profile)

1. Swain, Zachary (University of Delaware, Material Science and Engineering)
2. Mackay, Michael E. (University of Delaware, Materials Science and Engineering)

Author and Affiliation Lines (in printed abstract book)
Zachary Swain and Michael E. Mackay
Materials Science and Engineering, University of Delaware, Newark, DE 19716

Speaker / Presenter 
Swain, Zachary

Keywords
additive manufacturing; flow-induced instabilities; polymer melts

Text of Abstract
Extrusion defects and instabilities present in polymer processing have been researched in industry for decades. With the advent of the fused filament fabrication (FFF) additive manufacturing technique, small-scale extruders have become the common polymer processing tool of desktop 3D printers. Despite producing flow rates that are orders of magnitude smaller than industry extrusion lines, these compact extruders are still capable of producing pressure drops up to 5000 psi. High pressures producing small flow rates, when coupled with the filament feedstock typical of FFF extruders as well as a generally unoptimized extruder design, present new exercises in mitigating heat transfer limitations and processing instabilities. Sharkskin, melt fracture, die lines, and die swell are all observed in extrudate from a desktop FFF extruder, their impact on the additive manufacturing process is discussed, and methods of abating these phenomena are investigated.