Page 61 - Plastics News May 2018

teChnoLogy

Cheap 3-D printer can produce self-folding plastic materials

esearchers at Carnegie Mellon University have used an emerge from the 3-D printer as flat, hard plastic. When
Rinexpensive 3-D printer to produce flat plastic items the plastic is placed in water hot enough to turn it soft
that, when heated, fold themselves into predetermined and rubbery — but not hot enough to melt it — the folding
shapes, such as a rose, a boat or even a bunny. Lining Yao, process is triggered. "The software is based on new curve-
assistant professor in the Human-Computer Interaction folding theory representing banding motions of curved
Institute and director of the Morphing Matter Lab, said area. The software based on this theory can compile any
these self-folding plastic objects represent a first step arbitrary 3-D mesh shape to an associated thermoplastic
toward products such as flat-pack furniture that assume sheet in a few seconds without human intervention," said
their final shapes with the help of a heat gun. Self-folding Byoungkwon An, a research affiliate in HCII.
materials are quicker and cheaper to produce than solid
3-D objects, making it possible to replace noncritical parts EconCore’s Thermex Technology
or produce prototypes using structures that approximate
the solid objects. Molds for boat hulls and other fiberglass gains success
products might be inexpensively produced using these
materials. Yao presented her group's research on this elgium-based EconCore has developed and
method, which she calls Thermorph, at CHI 2018, the Bcommercialized technology for the continuous
Conference on Human Factors in Computing Systems, April production of honeycomb sandwich materials. This
21-26 in Montreal, Canada. Yao and her research team company's technology, called ThermHex, allows
were able to create self-folding structure by using the lightweight honeycombs to be produced from a wide
least expensive type of 3-D printer — an FDM printer — and range of thermoplastics and a variety of skin materials
by taking advantage of warpage, a common problem with (including nonplastic ones) depending on the targeted
these printers. "We wanted to see how self-assembly could application. The skin materials are bonded in line to
be made more democratic — accessible to many users," the cores. Transportation is a major focus area for
EconCore. Its technology fits seamlessly into the ongoing
lightweighting trend in the automotive industry and is
already being used in numerous automotive applications
in Asia and Europe.
EconCore licenses the technology to customers around
the world; one of the most recent of which is Fynotej,
a manufacturer of automotive nonwovens and industrial
carpets based in Mexico City. It is EconCore's first North
American licensee to focus on automotive applications,
said EconCore's Chief Operating Officer Tomasz
Czarnecki.Fynotej went into production earlier this year
Yao said. FDM printers work by laying down a continuous with a range of honeycomb sandwiches for automotive
filament of melted thermoplastic. These materials contain interiors, including the trunk space. These products,
residual stress and, as the material cools and the stress polypropylene honeycomb boards branded Fynocore,
is relieved, the thermoplastic tends to contract. This have a PP honeycomb core with skins — thermally bonded
can result in warped edges and surfaces. "People hate in-line — of either solid PP sheet or with a nonwoven
warpage," Yao said. "But we've taken this disadvantage surface finish. One other licensee in North America
and turned it to our advantage." To create self-folding mentioned by Czarnecki was Wabash National Corp., a
objects, she and her team precisely control this process leading producer of semitrailer and truck bodies that
by varying the speed at which thermoplastic material is has been using composites for weight reduction purposes
deposited and by combining warp-prone materials with for two decades. It developed a product featuring a
rubber-like materials that resist contracture. The objects thermoplastic honeycomb core with metal skins.

61 May 2018 Plastics News