Senior Design Expo 2019

PLASTICS
Thomas Orr, Aaron Thompson,
Jose Pablo Rueda Molina, Erik Boyle
Advisor: Josh Browne
Our project drew inspiration from work done
at MIT on printing free-form meshes into gel
like material. This gets away from a layerbased
process and thus allows for
considerably faster printing processes.
Additionally, the beam size being used is
several millimeters in magnitude, allowing
for the creation of robust structural shapes.
However, it is currently limited to resin type
materials. This limits fundamental strength as
either the resin is kept soft until it it rebonded
(which could be at any point in the future of
the printing process) or the resin bond isn’t
fully reptated (entangled with the existing
polymer molecules). This led us to the
ideation of a thermoplastic variation of the
gel printing process, replacing the
irreversible cure hardening process with a
reversible melt hardening process.
On the hot end side this would mirror
the approach used by conventional FDM:
filament is pushed through a hot region and
then extruded onto existing structures. Upon
extrusion, it bonds to existing material
through a process of reptation. However, as
limitations in current approaches to bridging
(bonding between two pillars in a print with
no underlying support) in FDM show, it is
impossible to print over nothing without
some high degree of sagging. To circumvent
this issue we propose to rapidly cool the
polymer by passing chilled fluid over it in a
small surface layer. We have tested different
coolants, yielding variable results. The
motions of the extruder can be hardcoded or
can be obtained through a path-finding
algorithm that necessarily takes into account
the position of the already-printed beams and
trusses, to avoid collisions with these. The
geometry of the head of the extruder, along
with the unorthodox build-plate necessitate a
non-trivial path-finding algorithm, but one
that yields many possibilities when it comes
to creating 3D structures. Thus, our project
revolutionizes the field of digital
manufacturing.
References:
Crump, S. S. (1989). U.S. Patent No.
US5121329A. Washington, DC: U.S. Patent
and Trademark Office.
Gordon, M. C. (2015). U.S. Patent No.
US20160207263A1. Washington, DC: U.S.
Patent and Trademark Office.
Kanada, Y. (2015). U.S. Patent No. US
20150.039 113A1. Washington, DC: U.S.
Patent and Trademark Office.
Mueller, S., Im, S., Gurevich, S., Teibrich,
A., Pfisterer, L., Guimbretièe, F. & Baudisch,
P. (2014, October 5). WirePrint: 3D Printed
Previews for Fast Prototyping. Retrieved
November 9, 2018, from
http://groups.csail.mit.edu/hcie/files/researc
h-projects/wireprint/2014-uist-wireprin t-
paper.pdf
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