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#2284
3D PRINTING: TAKING FLIGHT ONE LAYER AT A TIME
Mary Heyne (mah255@pitt.edu), James Herrmann (jph59@pitt.edu)
Abstract–An emerging technology that has the potential to
satisfy the constantly changing needs of manufacturing is a
type of additive manufacturing known as 3-dimensional
printing, or more simply, 3D printing. 3D printing comes in
various forms, from machines that can fit on a desktop to
larger, more sophisticated devices that require a much
grander scale and knowledgebase. The commonalities
between all 3D printing processes, however, are that they all
translate a digital file into a physical object by depositing
and fusing together layer upon layer of material until a full,
three-dimensional part is produced. This paper will explore
and assess the use of 3D printing as it pertains specifically
to the aerospace industry, an industry which has embraced
additive manufacturing as having immense potential for over
three decades. An overview of 3D printing will be provided,
as well as specifics explaining the selective laser sintering
process, a commonly used 3D printing process in the
aerospace industry. Additionally, specific aircraft
components manufactured using 3D printing will be
highlighted. Finally, the impact 3D printing could have on
manufacturing will be examined as it pertains specifically to
the aerospace industry, but also as it concerns
manufacturing on a broader scope.
finishing included. This result is achieved by converting a
digital file into a physical object using a machine, or 3D
printer, that lays down layer upon layer of material until a
whole object has been created or, as the name suggests,
printed.
The 3D printing process is currently being utilized by
several industries, including the automotive and aerospace
industries, and offers a great degree of freedom in design
and customization. While initially gaining traction as a form
of rapid prototyping that allowed engineers to have a test
object for designs within hours, 3D printing has progressed
into an effective direct manufacturing technique, allowing
for design and redesign to come to fruition quickly without
the expensive investments required by more traditional
manufacturing techniques.
The aerospace industry, in particular, has become known
as a leader of 3D printing integration and is currently one of
the forerunners in the development of this technology as a
direct manufacturing approach, with many printed
components presently making their way into military and
civilian aircraft [1]. 3D printing promises to cut weight,
improve the efficiency of components, cut down on
materials, and expand design possibilities, all of which are
major factors as to why the aerospace industry has invested a
great deal in the development of AM. The most common
process used by the aerospace industry is known as selective
laser sintering. This process in particular will be explored,
and components created using laser sintering will be
presented to analyze the benefits of using AM within the
aerospace industry. Finally, as 3D printing becomes more
prolific in niche industries such as the aerospace industry
and the benefits are more widely broadcasted, other
industries will begin to employ the process for their own
uses. Thus, the impact 3D printing will potentially have on
manufacturing more generally will also be examined as a
final comment on 3D printing and its application as a direct
manufacturing process.
Key Words– 3D printing, Additive manufacturing,
Aerospace industry, Direct digital manufacturing, Selective
laser sintering, Powder bed fusion
CREATING THE IMAGE
Open up the hood of a car, and take a moment to consider all
of the parts and components before you. Take a longer
moment to ponder how all of those components are made.
Most of them are metal, and most of them are manufactured
using processes that are subtractive by nature. Such
subtractive manufacturing begins with solid blocks of metal
and proceeds by removing pieces of metal bits at a time,
whether by drilling, grinding, milling, or other techniques.
Ultimately, the final product is one in which holes, grooves
and pathways have been created by the removal of material.
Now imagine a process in which those holes, grooves and
pathways could be built into the component from the start,
without requiring any material to actually be removed from
an initial block of metal. The material that would be
removed could actually never be there in the first place. This
process does exist—3D printing.
Simply put, 3D printing, or additive manufacturing (AM),
allows for a component to be manufactured by joining
materials together to create a whole while removing very
little, if any, material throughout the entire build process,
University of Pittsburgh
Swanson School of Engineering
SUBTRACTION TO ADDITION
A Cross-Section of History
3D printing arrived on the scene in the mid-1980s when a
computer-controlled process called stereolithography was
invented by Charles Hull [1]-[2]. Stereolithography builds
three-dimensional objects by successively hardening the top
layer of a pool of resin with an ultraviolet laser [1]. The
object begins as a computer-designed image and ends as a
hardened resin comprised of cross-linked polymers. The
ultraviolet laser traces a cross-sectional pattern of the part
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and cures the polymer resin, allowing it to undergo a process
called polymerization, which creates three-dimensional
networks of polymers and, consequently, a threedimensional object [3].
Stereolithography, and 3D printing in general, was
developed as a means for creating prototypes quickly and
became known as rapid prototyping [2]. Such a process was
needed because computer-aided design programs, or CAD
programs, were becoming commonplace with the spread of
computers. Stereolithography stepped in to link the
computer design to the solid object by allowing the digital
format to be sliced into two-dimensional cross-sections and
converted to the layers of material making up the prototype.
The success of stereolithography as a prototyping
mechanism paved the way for the development of other
processes that could use different materials and curing
methods. Some of these processes include selective laser
sintering, electron beam melting, and inkjet 3D printing [3].
The aerospace industry in particular embraced rapid
prototyping for developing new and highly customized parts
for aircraft, and the emergence of 3D printing as a valuable
tool in this industry has played a major role in pushing the
development of AM even further.
As various processes and technologies developed and the
materials that could be used expanded from polymers to
include metals and ceramics, 3D printing began to be
explored as a method of direct manufacturing, particularly
for very small production runs and highly customized
components because it could avoid the tooling costs
associated with subtractive processes. 3D printing has
become especially useful for manufacturing complex parts
which include internal structures that are difficult to access.
For example, metals can essentially be corrugated to allow
air channels to be built into engine parts to optimize cooling.
This corrugation is not readily possible using traditional
methods.
According to Terry Wohlers, who runs Wohlers
Associates and is a researcher specializing in AM, more than
20% of the objects produced by 3D printers are end-use
products as opposed to prototypes [4]. Companies within the
aerospace industry, such as Boeing and the EADS group
(formerly known as the European Aeronautic Defence and
Space Company), have led the way [5], especially as it
became more evident that 3D printing could allow for
designs that were otherwise impossible to produce [6]. This
notion as it pertains to the aerospace industry, as well as
specific discussion on selective laser sintering, will be
explored in much greater depth, but prior to embarking on
the details of process, the basic method that is common to all
forms of AM will be explained.
the layers are fused together. These differences can affect
how accurate an object is when compared to the initial
design, as well as the properties, both mechanical and
material, of the final object [2]-[3]. Still, all processes begin
with a digital file created by a CAD system and follow the
steps shown in the diagram below.
FIGURE 1
THE BASIC 8-STEP PROCESS FOR 3D PRINTING [3]
As stated previously, the process is initialized by the
creation of a CAD file detailing a three-dimensional object.
Following this first step, the CAD file is converted to a
standard file format [3]. This standard file format has until
recently been the STL format, which stands for the
stereolithography format. However, as recently as
September 2011, a new file format called AMF, an acronym
for additive manufacturing file format, has been approved to
replace STL [7]. A standardized file format is important for
obvious reasons, allowing files to be easily exchanged
amongst individuals using varying programs and ensuring all
AM machines can produce any given drawing as long as it
meets the production requirements of a printer. Once the file
is standardized, it is then transferred to the printer. Prior to
the actual build of the object, the machine must be set up
according to the parameters of various points of interest,
including the materials being used, the desired layer
thickness, the energy source and the length of the build [3].
Following the digital preparation, the build begins.
Building the part is automated, and machines are capable of
running without any intensive supervision. “Superficial
monitoring,” however, should occur to safeguard against
errors, which can include materials running out or power
source problems [3]. It is during this phase of the process
where the most differences from one method to the next
occur. Lasers or electron beams can be used to fuse materials
together. Layers of powder can be deposited and melted or
liquid resins can be cured. Selective laser sintering, for
example, requires the materials begin in powder form. As
one layer of material is solidified, another layer of material
is deposited on top and the process continues until the object
is completed [8].
The Layers of Process
Every AM technique follows the same basic process.
Differences arise from the materials each process is capable
of using, how the layers of material are produced, and how
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Next, the part is removed from the machine and postprocessing of the part occurs if needed. Parts may need to be
polished, cleaned, painted or treated in order give a desirable
end product [3]. Finally, the product is put to use, which can
mean finding its way into an aircraft and taking flight.
Accordingly, a great deal has been invested in 3D printing to
ensure it is a process up to the task of handling the stresses
and strains created by flight.
Furthermore, the accuracy of the three-dimensional
object is of immense concern, especially when the object is
being utilized as the final product. As such, certain processes
have to effectively qualify for specific purposes, especially
when limited tolerances are of the utmost importance such as
in the aerospace industry. When there is much at stake, as is
the case with aircraft and the components they are comprised
of, accuracy must be high. Converting a three-dimensional
image into two-dimensional cross-sectional layers and then
building from the layers thus results in “an approximation of
the original data” [3]. The following figure exaggerates this
approximation on a sphere, which is symbolic of the
complex shapes and curves often created using 3D printing.
process, or sintering, is now able to utilize more advanced
heating sources and lasers so that the materials and final
products are comparable to components produced via a more
traditional subtractive method. As Hans Langer, CEO of
Electro Optical Systems (EOS) based in Germany, states,
“I’m a physicist, and I didn’t believe that something
manufactured from a powder could be just as strong or
almost as strong as something cut from a solid” [2]. Langer’s
company manufactures the laser based systems that are
integral to SLS.
SLS is “based on the fact that a thin layer of
powder…can be heated with a laser so the powder particles
are softened or partially melted and stick to each other” [10].
FIGURE 2
FIGURE 3
APPROXIMATION OF 2D TO 3D DATA [9]
DIAGRAM OF SELECTIVE LASER SINTERING PRINTER [11]
The layers, therefore, should be as thin as necessary to meet
the required accuracy for any given component. The
accuracy, in addition to the surface smoothness of the
component, is dependent on how thin the layers are [10].
The process that many companies within the aerospace
industry employ is the selective laser sintering process
because it is a process that is able to meet the requirements
for an end-use product.
The materials used in SLS begin in powder form like in all
PBF processes. This powder is rolled or spread across a
“build area” using a leveling roller [12]. The layers of
powder are incredibly thin, usually around 0.1 mm thick or
less [3]. The build process takes place in an enclosed
compartment filled with nitrogen gas. The process cannot
occur in the open air because the powdered material is
susceptible to oxidation and other forms of degradation. The
powder is incredibly fine, and therefore, the incredibly high
surface area of the particles leaves them vulnerable. The
powder in the build area is heated to a temperature just
below the melting point of the powdered material and is
maintained at that temperature for the duration of the build
using infrared heaters [3].
Material that is pushed up into the build chamber by the
powder feed piston is also preheated prior to entering the
chamber. This preheating is incredibly important because it
helps prevent warping associated with drastic changes in
temperature. Preheating also helps to minimize the amount
of energy required of the laser. The purpose of the laser is to
raise the temperature of the material from just below the
melting point to just above the melting point of the material
SLS: LASER FOCUS
From Powder to Purpose
Selective laser sintering (SLS) is a type of AM that is known
as powder bed fusion (PBF). PBF processes were among the
first 3D printing processes to be commercialized, and SLS
was the first of the PBF processes to attain commercial
status [3]. SLS, like stereolithography, was developed as a
rapid prototyping technique and was initially used to
produce plastic prototypes. However, metal and ceramic
powders can now be used in SLS, both of which will be
discussed in the following section. Additionally, the fusing
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along the cross-section of the part [12]. Therefore, if the
powder is already close to the melting point temperature, the
laser only has to supply enough energy to raise the powder a
few degrees to above the melting point.
The job of the laser, therefore, is to melt the powdered
material. The laser is directed in the pattern of a crosssectional layer of the part using beam-deflecting galvano
mirrors [13]. After the material is melted, the laser then
provides just enough energy to sinter, or fuse, the newly
melted material to the previous layer. The lasers used for
SLS are often carbon dioxide lasers [3], which produce highpower beams of infrared light with continuous waves,
allowing the sintering to progress uninterrupted [14]. There
is quite a bit of research going into the development of new
lasers, including ytterbium fiber lasers, which would
potentially allow the use of nearly any metal powder during
the SLS process because of their high power output [8]. The
powder that is not needed for the cross-section of the part is
not fused together and remains loose around the solid
portions of the part. This acts as a support for the part as the
build process continues and can be reused for other
components [3].
After one layer is complete, the build platform is lowered
by the build piston a distance equivalent to the thickness of
one layer of material. A new layer of powder is spread
across the powder bed and the process is repeated [3]. To
summarize SLS, the laser beam scans the cross-section,
melts the required material and sinters the material to the
previously hardened material. New material is then spread to
allow the process to continue.
The term ‘sintering’ can actually refer to four different
binding processes: solid-state sintering, chemically-induced
sintering, liquid-phase sintering (partial melting), or full
melting [13]. The solid-state and liquid-phase sintering
processes are the most commonly used in the aerospace
industry, and they ultimately end up producing very similar,
if not identical, results [3]. In solid-state sintering, necking
occurs between adjacent powder molecules (Figure 4).
be liquefied during the process. This is particularly useful
when alloys are being used to build a part. One portion of
the alloy becomes the binder if it has a lower melting
temperature than the other components of the alloy (Figure
5).
FIGURE 5
STAINLESS STEEL, COPPER POWDER MIXTURE UNDERGOING LPS.
A –STEEL PARTICLE, B - MOLTEN COPPER, C - POROSITY [13]
Both solid-state and liquid-state sintering are common
processes for fusing materials that are frequently found in
aerospace components. A discussion of these materials
follows.
Material Gain
Materials are of the utmost importance in the aerospace
industry. Aircraft materials must be strong enough to
withstand the stresses placed on them during take-off,
landing and flight, but they also must be lightweight to
reduce the amount of fuel burned. For these reasons,
aerospace engineers continue to seek out materials that have
a high strength to weight ratio. Many current day aircraft and
aircraft that are being developed for the future use
lightweight carbon-fiber composites [4], but metal cannot be
entirely erased from the picture. Thus, the metals used in the
aircraft should be as lightweight as possible.
A metal that meets the above criteria is titanium.
Titanium is known to have the highest strength-to-weight
ratio of any metal, and it is also corrosion resistant. These
two facts make titanium an obvious choice for use in
aircraft. Furthermore, titanium responds very well to the
SLS process, allowing components to be produced with high
mechanical performance [15]. Multiple companies across the
aerospace industry, including GE, EADS and Boeing, are
incorporating titanium components produced using SLS into
their aircraft [1]-[15].
Nickel-based alloys are also receiving a great deal of
attention as an AM material, with the Additive
Manufacturing Consortium, a US-based group hoping to
increase 3D printing use within the aerospace industry,
focusing on nickel-based alloys in addition to titanium.
FIGURE 4
ILLUSTRATION OF PARTICLE NECKING DURING SINTERING [3]
Essentially, “the main driving force for sintering is the
lowering of the free energy when particles grow together”
[13]. Solid-state sintering is advantageous because a large
number of materials can be utilized in this process. Liquidphase sintering, by contrast, requires that a binder material
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Inconel 625 and 718 are high-temperature nickel-chromium
alloys that engineers hope to incorporate into aircraft
engines produced using SLS [15]. In addition to nickelbased alloys and titanium, stainless steel is also available for
use in SLS [4], though it is not as lightweight as titanium or
as temperature-resistant as nickel-based alloys. It is widely
believed, though, that innovation of metallic materials in
tandem with AM and SLS is the future. As Andy Hawkins, a
research designer for EADS, states, “We have been looking
at metallic capabilities and that’s where we knew we would
always see the biggest innovation” [5]. Further SLS metallic
materials research is headed towards incorporating metallic
portions into composite components [5].
As well as metallic materials, SLS is also capable of
using thermoplastics and nylons. Plastics have been used for
decades during rapid prototyping. Plastics, however, are
further being developed for use in final products as well,
with more and more plastics qualifying for AM as time
passes [15]. Nylon powders are also being used to build
functional prototypes and final products [8]. Companies
such as GE and Boeing are experimenting with laser
sintering ceramic pastes, hoping to open up new possibilities
for engines [1]. Ceramics are able to withstand incredibly
high temperatures, potentially making them an excellent
material for high-temperature applications such as inside an
engine. However, because of the brittle nature of ceramics,
they could only be effective if components could be
manufactured using a process that would not promote
surface cracks. Surface cracks would result in a fast fatiguerelated failure in the case of ceramics. SLS, however, could
be the answer to this.
SLS is developing into a method that is able to handle a
growing number of materials as more research is done on
how different materials react to sintering. Many materials
that are commonly used in the aerospace industry are also
becoming commonly used in SLS. However, such discussion
of lightweight and industry-appropriate materials leaves
unattended what is probably the largest benefit of AM:
designs that were never before thought possible.
If a traditional subtractive manufacturing process is
considered, it is understood that a component is the result of
cutting away at a solid piece of material. Perhaps the
component is manufactured in a few separate pieces and
then assembled at a later juncture, but in using subtractive
manufacturing, the creation of every piece results in a great
deal of material waste. In the aerospace industry, this is
known as the ‘buy-to-fly’ ratio, and according to Steve
Beech, an AM expert with Rolls-Royce, this ratio “can be as
high as 13 to 1, meaning that for every 13 kilos of titanium
bought, 1 kilo remains in the final product” [8], or nearly 30
pounds down to just over 2 pounds. 3D printing, on the other
hand, requires only about ten percent of the raw material
when compared to subtractive processes [4]. This has the
potential to reduce the buy-to-fly ratio to close to 1 to 1 [16].
GE has estimated it can look to save approximately $25,000
in material for each jet engine produced if 3D printing is
used on a commercial scale [1].
This incredible gain in material efficiency is due to how
the part is manufactured. Instead of removing material from
where it is not needed, 3D printing never puts it there in the
first place. Instead, it builds a part layer by layer and only
uses the required material for each successive layer. While
some machining might be necessary in post-processing, it is
limited compared to the traditional processes (Figure 6).
THE AEROSPACE INDUSTRY: LESS IS MORE
FIGURE 6
TRADITIONAL VS. ADDITIVE MANUFACTURING STARTING MATERIALS AND
WASTE MATERIALS (SCRAP) [17]
Why 3D Printing?
Material efficiency creates less waste and also leaves more
funding for further development of components or the
manufacturing process itself.
Additionally, if 3D printing is employed, designs are no
longer limited to manufacturing constraints. A component
no longer has to be designed according to how it can be
built, but rather, it can be designed according to what the
component requires and only what the component requires.
AM puts very few, if any, limitations on the design of the
component, assuming it is designed according to the
technical constraints of its application. Hawkins further
elaborates on the benefits of AM: “If we only add material
Additive manufacturing with lightweight materials does not
even begin to encompass the big picture as it pertains to the
aerospace industry. It is true that AM is an excellent way to
build specialized parts within a research setting. It is also
true that AM can build components with highly specialized
engineering materials that rival components built using the
same materials coupled with subtractive processing.
However, what this limited view leaves out is how the
components are built and how this process can have a
revolutionary effect on the initial design.
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where we have a load path, we can get a 50-70% weightsavings over conventional components” [15]. In other
words, “You only put material where you need to have
material” because the parts themselves can be better
optimized for their purpose [4]. This requires a new way of
thinking, allowing engineers to use designs that were never
before thought possible. Hawkins makes it a point to state
that this new design process is going to require some getting
used to, though: “There’s a need to change the way
manufacturing engineers think. The technology is only
beneficial if we understand the design. Our new engineers
need to be able to open up their minds and understand new
ways of working” [5]. If a new way of thinking can be
embraced, however, 3D printing could become the ideal
manufacturing process within the aerospace industry.
A decrease in design limitations leads to a decrease in the
amount of material in the final component. In subtractive
processes, portions of components exist only because there
is no way to effectively remove the material. However, 3D
printing eliminates this requirement, allowing the overall
weight of each component to be reduced. The combination
of lightweight materials and 3D printing is able to drastically
cut down on the weight of components, which is a critical
factor in design and fabrication within the aerospace
industry. As Chris Wilkinson, an engineer for AeroSystems,
states, “Weight equates to cost in our industry” [2]. A
reduction of 1kg in weight on an aircraft results in a savings
of approximately $3000 per year in fuel costs [4]. Curbing
the fuel requirement leads to a decrease in carbon dioxide
emissions. This coincides with a desire to operate on a more
environmentally friendly level. Additionally, should such
weight-savings be applied to commercial airliners,
customers could potentially see a decrease in ticket prices.
AM further reduces costs by eliminating many of the
typical
expenditures
associated
with
traditional
manufacturing. With the use of a 3D printer, a design team
can print a part without having to invest in the tooling
process [18]. Furthermore, only one part has to be printed.
When tooling occurs for subtractive processes, the
expectation is that multiple parts will be manufactured,
especially if a company wants to recover initial costs. 3D
printing, however, eliminates this necessity. Thus, parts can
be made quickly and in small production runs.
The advantages of 3D printing for the aerospace industry
are huge, and as the potential is even more fully realized, the
proliferation of components manufactured using 3D printing
will only continue. Presently, however, these advantages are
being realized on a scale larger than many understand. For
example, Boeing alone already has about 20,000 parts
manufactured using SLS in military and commercial aircraft
applications [1].
printing in applications that are not critical to flight [1].
Companies are starting on a smaller scale with hopes of
progressing into making larger and more important
components as the technique becomes more fully developed.
EADS, the company behind the Airbus, has been using
3D printing to create hinges for jet engine covers (Figure 7).
FIGURE 7
JET ENGINE COVER HINGE [19]
The hinge in the foreground is made using 3D printing,
while the hinge in the background is the equivalent
subtractive model. The printed hinge is evidence of a drastic
change in design and exemplifies how 3D printing can be
utilized to allow a component to be manufactured in a more
optimized and weight-saving manner.
The fuel injection nozzle shown in Figure 8 was also
manufactured using 3D printing. GE is using cobalt-chrome
powder to print these fuel injection nozzles [20], which are
excellent candidates for the use of AM because of the
complex internal structure.
FIGURE 8
FUEL INJECTION NOZZLE [21]
Along with manufacturing fuel injection nozzles, GE is
using SLS to manufacture titanium strips that are attached to
engine fan-blade edges. These strips allow for more efficient
airflow while also deflecting debris from crucial components
of engines [1].
Parts to Planes
While AM continues to be developed and qualified for
further applications, aerospace companies are using 3D
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failure” [24]. So while unpredictability is a concern, AM is
actually proving itself to be rather predictable.
Additionally, the materials available and approved for use
with the AM technology are still limited [1]. While much
research has gone into expanding this list over the past
decade [2], inadequacies exist, especially when compared to
traditional manufacturing techniques. Materials have been
specifically designed for subtractive manufacturing
applications, and when manufacturing techniques are
drastically changed, as they are with 3D printing, the current
materials must be safely adapted. In a sense, it becomes a
process of starting over and requalifying existing materials
for AM as well as developing new materials.
Regardless, there is great potential for the marriage of
AM and the aerospace industry. Within the past five years,
companies have been joining together to help progress AM.
In 2008, Boeing, EOS, Evonik Industries and MCP HEK
Tooling joined the University of Praderhorn to form the
Direct Manufacturing Research Center (DMRC) in Germany
[25]. Each company brings a different knowledgebase to the
research center, with Boeing heading the aerospace sector.
EOS, MCP HEK Tooling, and Evonik Industries all have a
particular interest in developing new materials for SLS [25].
Collaborations amongst industry leaders such as within the
DMRC are proof that AM is only going to advance in the
coming years.
Rolls-Royce, an aircraft engine manufacturer though
perhaps best known within the automotive industry, has
made a major move into AM with the Merlin Project. The
main goal of this project is to explore how 3D printing can
be used to curb the environmental hazards that arise during
the production of aircraft engines and during the use of the
engines [22].
FIGURE 9
ENGINE COMPONENTS: THE MERLIN PROJECT [22]
This project began in January 2011 and is expected to
continue until at least 2014 [23].
The above applications provide a representation of how
3D printing is being incorporated across the aerospace
industry. As materials and techniques develop more wholly,
AM will surely find its way into more components.
Flying with Aerospace
AM is already becoming a mainstay within the aerospace
industry, but it could also have profound impacts on other
industries. Obvious parallels exist between the aerospace
and automotive industries that could result in a ‘trickledown’ effect of sorts, particularly with engine-cooling
applications. However, 3D printing also could have impacts
that are less obvious. If AM becomes widely adopted, it
could restructure existing manufacturing methods. While it
seems unlikely that 3D printing could eliminate subtractive
processes, it is not improbable that AM will replace at least
some of these processes in a more mainstream fashion.
Furthermore, it is not a stretch to think that 3D printing
could eliminate manual labor jobs, and according to some, it
could incite a “manufacturing revolution” [26].
Additionally, there is a great deal of interest in bringing
3D printers into the home [27]. Several companies are
manufacturing 3D printers for personal use, but similarly to
the spread of digital music for example, legal ramifications
stemming from intellectual property rights and copyright
issues will surely crop up. Still, how far and how fast 3D
printing spreads will be a function of how well the aerospace
industry can further incorporate the technology into its own
applications. The aerospace industry has always been a
leader in AM, and there is no reason to think that this will
change.
Future Flights in 3D Printing
Despite the numerous advantages of 3D printing, several
issues must still be overcome in order for the technology to
be more fully embraced. AM is still a new technology. For
most of its duration, it has served as a prototyping process,
and it is only fairly recently that a major push is being made
towards direct manufacturing. As such, there is little data
regarding how the components will hold up over time. Initial
research indicates that the components created using AM,
and SLS in particular, are just as strong as more traditional
manufacturing methods [2], but research is nonetheless
continuing to more fully understand how these components
will hold up. As a component is built, each layer put down
could pose a threat for defect. According to GE’s Prabhjot
Singh, “A part is made out of thousands of layers, and each
layer is a potential failure mode” [1]. Boeing’s Mike Vander
Wel agrees, stating that the industry “[worries] about the
unpredictability,” posing the question, “can we repeat a
result to get 100 parts that are exactly the same?” [1]. The
lives of individuals are put at stake every time an aircraft
takes flight, and safety is a huge motivator. However,
according to Terry Wohlers, “Boeing now has parts on
flying military aircraft made by 3D printers without a single
7
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Herrmann
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SINTERING THE LAYERS TOGETHER
Additive manufacturing is undoubtedly a type of
manufacturing that holds great potential. Since finding its
beginning as a rapid prototyping process in the mid-1980s,
3D printing has already progressed into an end-use
technology. The aerospace industry has heartily embraced
AM since its inception and continues to invest time and
money into its development. As more research is done and
more data accumulates to back up 3D printing, more
confidence will be placed in AM. While AM is currently
being hailed as an up-and-coming technology, within time it
could become a technology as common as a desktop
computer, especially as the benefits become more apparent.
The aerospace industry already believes in its worth, but
others are catching on quickly, ultimately begging the
question of how long it will be before 3D printers are as
common as desktop computers.
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ACKNOWLEDGMENTS
Many thanks to the faculty, instructors, writing instructors,
and librarians who have aided in the writing of this
conference paper thus far. Specifically, thank you to Dr.
Karen Bursic, Katy Rank-Lev, and Nancy Koerbel for their
guidance during this writing process. Additionally, a very
special thanks is extended to Caroline Repola and Nicholas
Andes for their feedback and support.
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