Chemical Engineering January 2017 - 15

Carbon
critical areas. Because the roadmap
was created under the purview of
the not-for-profit LR Foundation, it is
in a position to examine longer-term,
industry-wide concerns that individual
companies might not consider,
Chung and Imrie explain. The roadmapping
process identified four principal
challenges that the AM industry
must resolve, including qualification
of AM technology, supply-chain standards,
workforce development and
realizing safety benefits.
Designed for 3DP
A significant portion of 3DP technology
is subject to patent protection,
so in some cases, raw material costs
are high where equipment vendors
produce proprietary materials for use
with specific printers. But the industry
is gradually moving toward a freer
model, where printer consumables
can be made by third-party producers.
The chemical process industries
(CPI) have become involved in developing
and supplying raw materials
specifically for use in 3-D printers.
Polymers designed for use in 3DP
require different properties than
those for injection molding, because
engineers need to consider the nature
of the process, in terms of rheology,
and the stability of the polymer
at high temperatures. Temperature
history is more important in 3DP due
to the significantly longer cycle times,
and while the pressure is generally
ambient in 3DP, injection molding
occurs at high pressures, controlling
the packing and dimensional stability
of the final part.
" To engineer a polymer specifically
for use in 3DP applications, you have
to think in parallel about the polymer
chemistry and the equipment in which
it will be used. For the material, you
need to focus on the thermal management
of the process system (that is,
how heating and cooling are accomplished), "
says Dominique Giannotta,
Solvay's manager of Sinterline nylon
products for Solvay S.A. (Brussels,
Belgium; www.solvay.com). Three
general approaches exist for developing
a polymer for 3DP, Giannotta
explains: modify the material to work
with existing equipment; start with the
material and design equipment that
works for that material, or a blend of
3D-print simulation
Solvay's Sinterline PA6 is involved in a
project that is an example of how 3Dprinted
finished parts could be developed.
Specifically, the project, known
as Polimotor 2, aims to demonstrate
operation of a fully plastic internal
combustion engine for a racecar. Solvay's
Sinterline material was used to
3D-print an air-intake plenum for the
engine. For Solvay, the inclusion of a
3D-printed part is helping to change
the prevailing mindset about the performance
possibilities for such components,
Giannotta says.
The Polimotor project is also illustrating
the importance of simulation
software in understanding the performance
and properties of a plastic
component before it is made. " Simulation
in 3DP is improving in its ability
and increasing in its importance,
as companies are adapting simulation
techniques currently used for
injection-molded parts to model 3Dprinted
parts, " Giannotta says. " We
are now assembling a raw-material
database to allow designing a finished
part from the beginning that will
be able to withstand the demands of
the application, " he remarks.
The Polimotor project represents
the first time that Solvay's new simulation
tool (known as MMI Technyl)
was used along with the Sinterline
PA6 material to produce a 3D-printed
final part. " In this case, experimental
testing of the plenum confirmed what
was indicated in the simulation work, "
Solvay's Giannotta explains, and the
simulation helped to answer questions
about how the part met engine
specifications. " Simulations offer the
ability to save time and money for experimental
testing, and also allow the
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
JANUARY 2017
FIGURE 1. Carbon's CLIP process addresses speed
and finish issues in 3-D printing of final parts
ability to modify the design prior to the
start of production, " he says.
Metals and quality
Alongside engineered plastics, " the
use of 3DP for manufacturing finished
metal components is a superhot
area right now, " says Wohlers,
and improved materials are becoming
available. For example, Alcoa
(Pittsburgh, Pa.; www.alcoa.com)
recently opened a state-of-the-art
facility for manufacturing metal powders
specifically engineered for 3DP.
Located at Alcoa's Technology Center
near Pittsburgh, the facility will
produce proprietary titanium, nickel
and aluminum powders optimized
for 3D-printed aerospace parts.
Alcoa also has invested in a range
of technologies to further develop
AM processes, product design and
qualification, the company says.
Because product quality and consistency
are critical in metal part production,
the atmosphere inside the
build chamber becomes very important.
Many 3DP processes use highpurity
inert gases, such as argon or
N2, to control the influence of oxygen
and water during the fabrication of the
part. However, the presence of traces
of O2 and humidity, due to incomplete
purging, machine leakages, or from
the metal powder itself, can negatively
affect mechanical properties or chemical
composition of the end product
- for example, leading to oxidation
of the metal, decreased fatigue resistance
and sub-optimal performance.
Industrial gas companies are recognizing
this need and getting involved
to support 3DP processes.
15
the two. Solvay is working mainly on
the latter two approaches, he says.
For example, Solvay was a pioneer
in developing the high mechanical- and
thermal-performing range of polyamide-6
(PA6) powders, known as Sinterline,
which are specially engineered for
selective laser sintering (SLS), a prominent
3DP technology class (for more
on 3DP techniques, see Chem. Eng.
February 2015, pp. 20-23).
Solvay is joined by BASF, Eastman,
Evonik and others in developing raw
materials specifically for 3DP.
http://www.alcoa.com http://www.solvay.com http://WWW.CHEMENGONLINE.COM
Chemical Engineering January 2017

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