C6
Paper #103
Disclaimer—This paper partially fulfills a writing requirement for first year (freshman) engineering students at the University
of Pittsburgh Swanson School of Engineering. This paper is a student, not a professional, paper. This paper is based on publicly
available information and may not provide complete analyses of all relevant data. If this paper is used for any purpose other
than these authors’ partial fulfillment of a writing requirement for first year (freshman) engineering students at the University
of Pittsburgh Swanson School of Engineering, the user does so at his or her own risk.
THE USE OF FUSED DEPOSITION MODELING IN SPACE TO IMPROVE
EFFICIENCY OF SPACEFLIGHT
Patrick Flaherty, [email protected] , Mahboobin 10:00, Tessa Veurink, [email protected] , Mena, 3:00
Abstract— Through the process of additive manufacturing
(AM), astronauts have the ability to 3-dimensionally (3D)
print rocket engine parts in space that will yield longerlasting products and provide several benefits to
spaceflight. In this paper, we will discuss the use of 3D
printing with filaments such as Acrylonitrile Butadiene
Styrene (ABS), a thermoplastic polymer that is used in cases
where impact resistance, durability, and other mechanical
properties are needed. In the case of rocket engine parts, ABS
has been used in Fused Deposition Modeling (FDM) to create
fuel injectors, combustion chamber linings, and impellers, as
well as some other 20 parts of the rocket engine. With the use
of AM, the cost and time required to develop such parts will
be severely reduced, providing needed sustainability in the
aerospace industry. Because of this, engineers and
astronauts will be able to 3D print rocket engine parts and
tools in space, which will eliminate the cost of launching the
manufactured materials to space. In this paper, we will
further discuss the implications of 3D printing rocket engine
parts in space for the advancement of space exploration and
spaceflight, as well as the effects AM will have on public and
private industry alike. We will also focus on the benefits AM
has in reducing manufacturing times and cost, as well as the
particular strengths and uses of ABS as a material.
Key Words — Acrylonitrile Butadiene Styrene, Additive
Manufacturing, Fused Deposition Modeling, Intellectual
Property, Rocket Engines, 3D Printing.
REVITALIZING THE SPACE INDUSTRY
Long after reaching its peak of popularity in 1968, the
space industry, led by the National Aeronautics and Space
Administration (NASA), has had a dwindling budget reaching
at times less than one third its peak [1]. The focus of the space
industry has moved from national security to space
exploration and scientific research, yet funding and public
interest has decreased. This has resulted in an increasingly
tight budget and has limited the exploration options
possible. With limited funding, the need for cheaper
alternatives in any facet of the industry has become more
significant. The space industry faces problems with costs and
University of Pittsburgh Swanson School of Engineering 1
03.31.2017
frequency of launches, while also looking for new and
cheaper alternatives to promote space travel. Recently, the
aerospace industry has begun utilizing 3D printing as a tool in
greatly reducing manufacturing costs and increasing
production. To combat the financial, manufacturing, and
frequency of launch problems, launching a 3D printer into
space and utilizing it to 3D print rocket engine parts aboard
the International Space Station (ISS) and other spacecraft will
help to more efficiently distribute the limited budget.
THE PROCESS OF AM AND FDM FOR 3D
PRINTING
Through the process of AM, astronauts have the ability
to 3D print rocket engine parts in space that will yield longerlasting products and provide several benefits to
spaceflight. When an engineer creates a digital design
through Computer-Aided Design (CAD) software, the 3D
printer processes the CAD file and creates the product through
AM and Fused Deposition Modeling (FDM). AM is the
process of layering material upon itself to create a final
product. Further, FDM uses the process of AM to extrude
heated material through a nozzle to layer and create the
designed product. Under constant pressure and in a
continuous stream, the nozzle extrudes material and moves
horizontally, while the building platform of the 3D printer
moves vertically to additively create the designed product. In
order to control the quality of the product, the nozzle
maintains a constant speed and pressure while extruding
material [2]. Below, Figure 1 details the process of FDM,
where a spool of material is processed through a heater
element. Then, the material is extruded through the nozzle
and additively creates the product. The support material acts
to aid the product in stability while being created. Once the
product is created, the support material can be torn off to
reveal the final product.
Patrick Flaherty
Tessa Veurink
thermoplastics, such as ABS, to create the solid product that
directly adheres to the building platform, eliminating the
issues that arise from using a resin pool.
USING ABS IN FDM
FDM 3D printers use thermoplastics, such as ABS, to
build
products
with
reliable
mechanical
properties. Thermoplastics are a group of polymers that,
when under high temperatures, are malleable and solidify into
sturdy structures once cooled. Thermoplastics melt when
they reach these high temperatures required to be molded so
a sample of thermoplastic does not break the bonds between
its molecules when heated [4]. ABS is a lightweight, yet
strong, thermoplastic that has been used more frequently in
the aerospace industry for its mechanical properties
[5]. Specifically, ABS has high impact resistance and can be
adapted to any situation by changing the makeup of its
components. In a durability and tensile study, conducted at
the University of Texas at El Paso, researchers determined
differences in the mechanical properties of pure ABS and
ABS with several other materials, such as Titanium Dioxide,
jute fiber, and a thermoplastic elastomer. Using FDM,
researchers 3D printed strips of pure ABS and ABS
compounds to compare whether the presence of other
compounds affected the ultimate tensile strength (UTS) and
ductility of pure ABS. The researchers determined that the
type of material blended with ABS resulted in different
changes to its material properties: titanium dioxide resulted in
a higher UTS, the jute fiber slightly reduced the UTS, but
increased the strength at fracture, and the thermoplastic
elastomer reduced the UTS, all compared to the pure ABS
sample [6]. From this study, it was determined that the
presence of reinforcing compounds to ABS affected the
mechanical properties in areas of fracture surface
characteristics and tensile qualities. In some cases, the
addition of a compound led to more brittle characteristics
compared to pure ABS, while other compounds were more
ductile, but also more brittle. Therefore, pure ABS provides
a functional product and sets a standard for comparison on the
optimal mechanical characteristics of a material needed for
3D printing rocket engine parts while using FDM.
FIGURE 1 [2]
Graphical representation of the process of FDM
Comparing FDM to Other Forms of 3D Printing
3D printing offers a variety of different forms of
processing and creating products, yet there are significant
advantages and disadvantages to each process. One such
process is FDM, which uses material extrusion to layer heated
material onto itself to create a stable product. With the case
of 3D printing rocket engine parts, strength, size, and
durability to high temperatures is necessary for
operation. FDM offers the option to use thermoplastics to 3D
print products, while other forms of 3D printing are not able
to create effective products with thermoplastics. For
example, Selective Laser Sintering (SLS) uses a heated laser
to melt powdered material that layers and bonds to itself,
slowly developing the final product [3]. Although the process
of SLS is similar to FDM, SLS yields different mechanical
properties of its products. When using metal powder, the
melted metal will not yield the desired mechanical properties,
such as geometry and print density, of an equivalent cast
metal. Because of the size of the project needed for 3D
printing rocket engine parts, a 3D printer using SLS would
have to be much larger, and therefore, more expensive. SLS
printers require a laser to operate, making them much more
expensive. 3D printers that use FDM can withstand creating
large products without increasing the price of the printer due
to the fairly simple design of the printer. Similarly, another
form of AM in 3D printing is Stereolithography (SLA). SLA
utilizes an ultraviolet laser to draw the desired project onto a
vat of liquid, called a resin pool. The resin would harden and
cure to create the product. Although this method makes
similar results, the actual printer and resin is incredibly
expensive [3]. Also, SLA would not be an effective method
for 3D printing rocket engine parts in space due to its resin
pool, which would be difficult to control in zero-gravity. In
comparison, the advantage of FDM is that it extrudes
Benefits of Using ABS as a Material
ABS proves to be an incredible material for the space
industry. As a thermoplastic, ABS is capable of being molded
into any shape through the use of FDM, and can be blended
with different elements or alloys to achieve a certain set of
desired mechanical properties. It is remarkably cheap and
lightweight and has a very high impact resistance. These
qualities make it ideal for printing the parts of rocket engines.
NASA has already used 3D printers in space and currently has
a long-term 3D printer known as the Additive Manufacturing
Facility (AMF) onboard the ISS. [7] The AMF primarily uses
FDM to print tools and material due to its availability, weight,
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and ease of use. One of the most recent prints from the AMF
is a socket wrench, which the crew of the ISS was able to use
due to its physical properties. ABS itself is not the strongest
or the most flexible material that can be used in a 3D printer,
but it is one of the cheapest materials and is incredibly useful
for its cost. The range of applications that ABS is successful
in has increased exponentially due to the blends that can be
made of ABS and other materials. This being said, ABS is not
the only material that NASA is using in developing rocket
engine parts. Some rocket engine parts have far more
intensive requirements, especially in handling high
temperatures which ABS would melt and deform in. In these
cases, highly durable and heat resistant metals will be used to
develop parts of rocket engines such as fuel injectors, or
combustion chambers, or NASA plans to one day develop its
own machine shop in space [8], an application where ABS
would be unbelievably useful and efficient.
which is very similar to selective laser sintering. The fuel
injector was made of nickel chromium alloy and similar in
size to injectors in smaller rockets but similar in design and
strength to injectors used in much larger ones [10]. What
once took 115 parts and months to fabricate by hand only
takes a couple of weeks and 2 parts utilizing AM. Early tests
of efficiency marked the injector as working flawlessly, and
with the incredible achievements in reducing labor and
manufacturing costs show incredible promise for the future of
AM in the aerospace industry.
ABS Onboard the ISS
3D printing represents an efficient method for which
astronauts on board the ISS may produce parts, tools and
repairs on sight and on-demand. This eliminates the need to
launch a shuttle with large, expensive, and heavy spare parts.
Storage aboard the ISS, space shuttle, or rocket could be better
utilized to send more material into orbit by sending large
amounts of filament instead. This will also reduce the amount
of greenhouse gases that the space industry release into the
atmosphere. As of right now, rocket launches “deplete the
ozone layer by no more than a few hundredths of one percent
of annually” [9]. Although this amount is undoubtedly small,
it is guaranteed to rise as space travel becomes more and more
prevalent in our culture. The same company that developed
the AMF is also developing a material recycler called R3DO.
The machine is designed to completely melt ABS or other
filaments and the prints of those filaments and create solid
filament that a 3D printer on board the space station would be
able to utilize. This would result in even fewer resupply
machines between Earth and the ISS and therefore save even
more money for NASA’s tight budget. The 3D printer on
board the ISS and the potential filament recycler, R3DO,
would be powered by the solar panels that power and charge
the batteries of the space station. In order to guarantee the
safety of the power consumption of the printer, it would only
be used when the solar panels have generated enough energy
to last until the next time the station is in view of the sun. The
solar panels on board the ISS already provide an excess of
power for the present activities of the crew, so the use of the
3D printer would not result in any monetary difficulty in
regard to power.
FIGURE 2 [11]
Newly 3D Printed Fuel Injector (Left), Polished 3D
Printed Fuel Injector (Right)
NASA also used AM in designing an incredibly
complex and efficient combustion chamber lining made of
thin copper. Copper is highly resistant to heat which makes it
ideal for use as a combustion chamber lining, but also results
in difficulties printing the design as the laser has difficulty
continuously melting the copper. By 3D printing the
combustion chamber lining, highly efficient and complex
airways can be manufactured within the lining to allow cold
gases to absorb the heat of the engine. This results in an
incredibly efficient engine lining that utilizes gas flow in a
manner that would be impossible if not for the use of AM
[12].
NASA has also produced a turbopump through AM. A
turbopump is necessary to supply fuel to the engine. It is one
of the most complex parts that NASA has tested with liquid
methane, as there are several turbines within its design that
can spin at rates as high as 90,000 RPM. Using AM to develop
the turbopump resulted in 45% fewer parts being used,
allowing the development of two turbopumps to be
financially viable and for testing to take place must sooner.
NASA’s team was able to test not only liquid methane as a
fuel, but also liquid hydrogen, a possible fuel that has
incredible cost saving benefits due to its availability [13].
NASA has printed other parts of rocket engines as well, which
all reduce the cost of manufacturing and the time that the
agency must wait before starting testing. AM encourages
more research and development due to the efficient use of
time. It also increases design space, as can be seen by the
copper combustion chamber lining.
ROCKET ENGINE PARTS
NASA has printed many parts of rocket engines. One
such part, a highly complex fuel injector, was 3D printed
using a method of 3D printing called Selective Laser Melting
3D PRINTING IN SPACE
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The AMF, manufactured by Made In Space, uses FDM
and is capable of printing with several different materials
including ABS. It is designed to print within the microgravity
present on board the ISS and is meant to be upgradeable,
which allows the printer to last the lifetime of the ISS. The
AMF is the successor to the First Zero-Gravity 3D Printer
(3DP). Astronauts used the 3DP in late 2014 to print the first
ever design to be 3D printed in space: a head-plate for the
printer itself. The AMF has also printed several designs on
board and is commercially available to the public, meaning
that with sufficient funds, an individual can order a design to
be printed on board the ISS. The printer has also been used by
the astronauts to develop a socket wrench that the astronauts
may use onboard the ISS. The implications of these findings
lead to the possibility of 3D printing rocket engine parts in
space and enabling space missions to continue longer without
the need for restocking tools or other parts on the spacecraft.
Currently, the AMF has maximum printing dimensions
of 14x10x10 cm [7]. With these printing dimensions, the
crew onboard the ISS is limited in what they can print. Yet,
the AMF is modular and meant to be improved, therefore in
the future, the AMF could print much larger products [7].
THE ETHICS AND DISADVANTAGES TO
3D PRINTING
With investment and development of 3D printing
technology, proliferation of 3D printing technology is sure to
follow. Most 3D print designs are developed by enthusiasts or
engineers and later submitted to one of many websites
dedicated to hosting design files that consumers can use with
their own 3D printers. With further research and development
in 3D printing and AM, more and more 3D printers will
become available to consumers. With more consumers
utilizing 3D printing, whether it be for recreational or
productive reasons, the possibility of individuals abusing the
open-source nature of 3D printing and ignoring patent laws is
much higher [15]. The files used by 3D printers are easily
created, edited, and transferred using CAD programs, which
raises questions about the security of the intellectual property
rights for those who develop new and incredible designs. 3D
printing websites will face problems just as the music and
movie industries have.
Although open-source as it pertains to software is far
from new, the possibility of open-source hardware becomes
more likely every day. With access to a 3D printer and the
materials required to print a design, an individual will have
access to the means with which to print the hardware they
desire at no additional cost other than the raw materials. This
is seemingly innocuous at first sight, but it is clear that this
possibility coupled with the likely abuse of copyright and
intellectual property rights can lead to the printing of
machines or hardware with no form of compensation going to
the corporation who owns the trademark or the engineer who
developed the design.
Developments in 3D printing will also have large
impacts on the economy. The aforementioned Fuel Injector
designed by NASA reduced the number of parts from 115 to
2 which greatly reduced manufacturing costs and time but
also required fewer workers to build. When NASA does adopt
this technology on a wider scale, they would eliminate much
of their manufacturing costs, but at the same time greatly
decrease the number of manufacturing jobs required. This is
of course a course of action that has been proven time and
time again; as cars became cheaper and safer people stopped
riding horses, as computers became cheaper and easier to use
secretaries became unemployed, and as 3D printing becomes
cheaper and more efficient, manufacturing jobs will be
replaced by the cheaper 3D printing alternative. Although this
effect of 3D printing is clearly negative, the benefits it has for
consumers are tremendous and organizations like NASA can
use this to extend the limited funding they receive.
There exists one final tremendous problem with the
proliferation of 3D printing; when a 3D print inevitably fails
and causes injury to some individual, who is to blame? Is the
engineer who developed the design at fault for developing a
broken product, or is the corporation who sold the 3D printer
the cause of the accident? It is clear that some unfortunate
Properties of ABS and FDM in Space
FDM provides a solid-base material, like ABS, to create
the 3D product, which can theoretically be compatible with
the microgravity environment, compared to liquid and
powder based AM technologies. Liquid and powder based
materials would not be compatible in a microgravity or zerogravity environment because it is not contained by gravity,
and therefore would not be able to be harnessed for 3D
printing. Although FDM extrudes material from the nozzle
directly to the building platform, there will still be
macroscopic and microscopic debris of solid ABS, possibly
due to the grip and local tear-off forces from the nozzle to the
building platform. Therefore, a potential 3D printer in space
would have to be controlled in a vented container, which
would eliminate potentially dangerous free-floating debris
from injuring passengers [12].
In microgravity for FDM 3D printing using ABS, the
orientation of the printer relative to Earth’s gravity vector
does not affect the results of the printed product due to gravity
being negligible in space. Regularly on Earth, FDM 3D
printing would be affected by gravity, and the orientation of
the printed material, whether it be long vertically or long
horizontally, would have an effect on the product’s durability
and tensile strength. Although in microgravity the orientation
of the 3D printed product relative to Earth’s gravity does not
have an effect on the mechanical properties of the product, the
manufactured products will have slightly different
mechanical properties than it would on Earth, such as surface
roughness, density, and surface and internal defects [14].
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Patrick Flaherty
Tessa Veurink
individual is going to one day fall victim to an unlucky
accident, but who to blame for that accident is difficult to
determine at best and likely is dependent on a set of
circumstances that cannot possibly be predicted at the
moment. If and when more problems arise from faulty 3D
printers and designs, there will need to be standards to follow
to compensate for these problems.
increasing shift to private industries, but nevertheless, new
techniques and technologies, such as 3D printing rocket
engine parts in space, could help to refocus the aerospace
industry and allow the budget they are granted to extend much
further.
Renewed Funding Under the New Administration
With a changing administration, it is difficult to
determine whether the aerospace industry will receive
adequate funding to invest in new explorations or expansions
of the industry. Therefore, there is a need for budget
conservation in any aspect of the industry. 3D printing has
become more versatile in the aerospace industry, and utilizing
the technology in space could help to conserve the tight
budget administered to the aerospace industry. To combat
continuous launches, launching a 3D printer into space and
utilizing it onboard the ISS and other spacecraft will help to
conserve the budget. FDM is able to withstand the constraints
of 3D printing in zero-gravity or microgravity, which is useful
onboard the ISS. To help maintain similar and quality
products, ABS is a useful thermoplastic used in FDM to 3D
print reliable products. Because of its mechanical properties
and its ability to withstand high temperatures and tension,
pure ABS is a reliable polymer that functions well within
FDM to create functional products and has the ability to
withstand the problem of 3D printing in zero-gravity. With
tools and parts breaking or malfunctioning onboard the ISS
and spacecraft, the use of a 3D printer would help to decrease
the amount of launches needed to resupply the spacecraft, and
therefore saves money, which could be allocated elsewhere
within the aerospace industry for further space exploration
and other missions. Specifically, using ABS to 3D print
rocket engine parts would not only help to save money, but
also would provide the aerospace industry with new pathways
of exploration. Although it is difficult to gauge how the
national budget will be distributed for the aerospace industry
under the new administration, any technology or innovation
that helps to save money will be useful for the aerospace
industry. Similarly, the shift from public to private industry
will also change the aerospace industry, and it may need
reevaluation before continuing onto significant missions. In
total, the addition of launching 3D printers into space for the
use of producing tools and parts will help to revitalize the
aerospace industry, while creating a solution to a limited
budget.
REDEFINING THE SPACE INDUSTRY
With a change of administration, there is a redistribution
of the national budget that determines what programs will
receive different amounts of funding. NASA, which is an
independent agency, would receive annual funding, which
would be determined by the executive branch. The Trump
administration have released their 2018 budget, within which
NASA has been allocated $19.1 billion, about $200 million
less than NASA is currently allotted. According to the
National Public Radio, the change in funding intends for
NASA to “expand public-private partnerships as the
foundation of future U.S. civilian space efforts” [16]. NASA
acting Administrator Robert Lightfoot stated the funding will
“enable us to effectively execute our core mission for the
nation, even during these times of fiscal constraint”. He
responded to the budget cuts by saying that “while this budget
no longer funds a formal Office of Education, NASA will
continue to inspire the next generation through our missions
and channel education efforts in a more focused way through
the robust portfolio of our Science Mission Directorate” and
that “This is a positive budget overall for NASA” [17].
Robert Lightfoot makes it clear that the proposed budget will
continue NASA’s core goal of exploration. The use of 3D
printing onboard the ISS will help extend this reduced budget.
The change of administration and distribution of the
budget could also shift the focus of NASA, encouraging
alternative options to conserve the allotted budget. Therefore,
using FDM and ABS to 3D print rocket engines in space
would help to extend the budget and would create more
opportunities for other expenditures. Additionally, a new
distribution of budget for space exploration could also lead to
a shift towards private industry instead of government control
of the space industry regarding exploration of the solar
system.
Transition to Private Industry
With the possibility of a changing budget, the aerospace
industry could look to shift more towards private ownership
or a combination of both private and public
ownership. Already, the aerospace industry has seen a shift
towards private corporations, such as SpaceX and Boeing,
partnering with NASA to execute smaller missions or
launches. Although, with a shift from public to private
industry, this could impact the funding that the public industry
receives. It is still uncertain which way the aerospace
industry will shift due to the new administration and
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ACKNOWLEDGMENTS
We would like to thank our Co-Chair, Julie Shields, for
advising us and offering advice on our paper. Additionally,
we would like to thank Ryan Carpenter for motivating and
encouraging us to work on this paper.
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