Tech Briefs Magazine - September 2021 - 46

Manufacturing &
Prototyping
Testing of the new prototype has
shown it saves about 35% in materials
used to print objects. For standard FDM
printers, the materials cost is about $50
per kilogram but for bioprinting, it is
close to $50 per gram. Saving 30% on
material that would have gone into printing
supports is a huge cost saving for 3D
printing for biomedical purposes, for
example. In addition to the environmental
and cost impacts of material wastage,
traditional 3D printing processes using
supports is also time-consuming.
Similar prototypes developed in the
past relied on individual motors to raise
each of the mechanical supports, resulting
in highly energy-intensive products
that were also much more expensive to
purchase and thus not cost-effective for
3D printers. If a prototype required 100
moving pins and the cost of each motor
was about $10, the entire cost is $1,000,
in addition to 25 control boards to control
100 different motors. The entire
build could cost well over $10,000.
The team's prototype works by running
each of its individual supports
from a single motor that moves a platform.
The platform raises groups of
metal pins at the same time, making it a
cost-effective solution. Based on the
product design, the program's software
would tell the user where they need to
add a series of metal tubes into the base
of the platform. The position of these
tubes would then determine which pins
would raise to defined heights to best
support the 3D printed product, while
also creating the least amount of waste
from printed supports. At the end of
the process, the pins can be easily
removed without damaging the product.
The system could also be easily
adapted for large-scale manufacturing
such as in the automotive and aerospace
industries.
For more information, contact Gary
Po lak o vic at polakovi@usc.edu; 213-740-9926.
Cladding and Freeform Deposition for Coolant Channel
Closeout
This method is a faster way to manufacture combustion chambers and nozzles for
aerospace propulsion as well as heat exchangers in oil and gas applications.
Marshall Space Flight Center, Alabama
ow-cost, large-scale liquid rocket en -
gines with regeneratively cooled nozzles
will enable reliable and reduced-cost
access to space. Coolant contained un -
der high pressure circulates through a
bank of channels within the nozzle to
properly cool the nozzle walls to withstand
high temperatures and prevent
failure. It has been a challenge to affordably
manufacture and close out the intricate
nozzle channels.
250µm
The micrograph on the left shows the quality of the bond at the interface of the channel edge and
the closeout layer; on the right is a copper channel closed out with stainless.
an interim material that sets up the base
structure for channel slotting. A robotic
and wire-based fused additive welding system
creates a freeform shell on the outside
of the liner. Building up from the
base, the rotating weld head spools a bead
of wire, closing out the coolant channels
as the laser traverses circumferentially
around the slotted liner. This creates a
joint at the interface of the two materials
that is reliable and repeatable. The LWDC
wire and laser process is continued for
each layer until the slotted liner is fully
closed out without the need for any filler
internal to the coolant channels.
One variation enables a bimetallic
part (copper/super-alloy, e.g.) to help op -
timize material where it is needed. The
46
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manufacturing process has been demonstrated
on a series of different alloys. In
hot-fire testing, the parts were exposed
to extreme combustion chamber temperatures
and pressure conditions for
1,000+ seconds. Micrograph examination
of the hot-fired test article verified
that the coolant channel closeout bonds
are reliable and that there is very little
deformation to the coolant channels.
NASA is actively seeking licensees to commercialize
this technology. Please contact
NASA's Licensing Concierge at AgencyPatent-Licensing@mail.nasa.gov
or call us
at 202-358-7432 to initiate licensing discussions.
Follow this link for more information:
https://technology.nasa.gov/patent/MFSTOPS-81.
Tech
Briefs, September 2021
L
NASA Marshall developed a robust
and simplified additive manufacturing
technology to build the nozzle liner
outer jacket to close out the channels
within and contain the high-pressure
coolant. The Laser Wire Direct Closeout
(LWDC) capability reduces the time to
fabricate the nozzle and allows for realtime
inspection during the build.
LWDC technology enables an im -
proved channel wall nozzle with an out -
er liner that is fused to the inner liner to
contain the coolant. It builds upon
large-scale cladding techniques that
have been used for many years in the oil
and gas industry and in the repair industry
for aerospace components. LWDC
leverages wire freeform laser deposition
to create features in place and to seal the
coolant channels. It enables bimetallic
components such as an internal copper
liner with a superalloy jacket.
LWDC begins when a fabricated liner
made from one material is cladded with

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Tech Briefs Magazine - September 2021

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