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Session B6
Paper 59
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 be 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
3D PRINTING INTO THE FUTURE: LASER METAL DEPOSITION IN THE
AEROSPACE INDUSTRY
Caleb Foglio, [email protected], Vidic 2:00, Nathan Bretscher, [email protected], Lora 3:00
Abstract — The recent development of Laser Metal
Deposition (LMD) technology in the field of metallic 3D
printing offers greater manufacturing flexibility than
traditional machining techniques. LMD is an additive
manufacturing process that utilizes a high intensity laser to
fuse metallic power with itself and/or an existing surface,
building up a new object layer by layer.
Since most LMD printers build structures using five axis
rotation which allows the printer to simultaneously move
along five different axes, LMD shines when it comes to
manufacturing complex geometric structures that otherwise
would be costly and time consuming to produce using
traditional machining methods. This makes LMD suitable for
rapid prototyping and product development, however
components produced by LMD are also strong enough to
serve as fully functional parts. Because LMD can be adapted
for a wide variety of shapes and structures on the spot, making
it ideal for producing complex aircraft components such as
turbines and engine parts within the aerospace industry.
Companies such as Boeing, for instance, are already building
functional metal parts such as turbines for their commercial
planes using this technology to save both time and resources.
Key Words — 3D Printing, Additive Manufacturing,
Aerospace, Direct Metal Deposition, Laser Metal Deposition,
Metallic Printing
intensity lasers to melt metallic powder into the desired shape,
and EBAM uses an electron beam to melt the powder [1, 2].
All of these printers have their strengths and weaknesses
but currently LMD appears to be the most well-rounded and
practical additive manufacturing method. LMD is fast,
resource efficient, and excels when it comes to producing,
coating, and repairing complex components. LMD may be
applicable in a variety of fields, but it is most notably
advantageous within the aerospace industry where
geometrically complicated components such as turbines,
rotors, and housings are expensive and time consuming to
produce with traditional manufacturing processes.
HOW LMD WORKS
LMD is a 3D printing process that utilizes a high
intensity laser beam and a fine metallic powder. The metal
that is used in a LMD printer must be in a fine powder form
in order for the machine to use it [1]. As seen in Figure 1
below, powder is fed through a nozzle located directly
beneath the laser onto a platform. The laser is focused on the
object’s surface and creates a melt pool which allows the
powder to melt and form a deposit that is fusion bonded to the
underlying surface. This process is repeated, and new material
is built up upon itself layer by layer until the product is
complete [3].
WHAT IS METAL 3D PRINTING?
A 3-dimensional (3D) printer is a type of printer that
creates 3D objects instead of 2-dimensional pictures as
traditional printers do. When 3D printers were initially
invented, they were limited to using only plastics and
polymers to create 3D shapes. 3D printers have since been
improved to create more complicated structures, but the
printers could not print using any other material types until
recently. Over the past few years, innovations in 3D printing
have allowed it to be possible to create 3D structures and
shapes using metal. Rather than using liquefied plastic
material, metal 3D printers use metallic powder to create
metal 3D objects. There are a few different types of metal 3D
printing such as Direct Metal Laser Sintering (DMLS),
Electron Beam Additive Manufacturing (EBAM), and Laser
Metal Deposition (LMD). Both DMLS and LMD use high
University of Pittsburgh, Swanson School of Engineering 1
3.3.2017
FIGURE 1 [4]
Diagram of an LMD Printer
Caleb Foglio
Nathan Bretscher
The powder can be virtually any metal or metal alloy of
the manufacturer’s choice such as nickel, cobalt, stainless
steel, or titanium as long as it is in powder form [2]. In most
LMD printers, the laser and nozzle are housed together in a
single unit that moves concurrently. Depending on the exact
LMD printer, either the laser and nozzle, the base platform, or
both can be rotated on multiple axes to form new objects of
different shapes.
mills machine in exactly the same way as traditional mills,
except receive precise inputs from a computer. The connected
computer usually runs a type of Computer Aided Design
(CAD) program where the user digitally designs the desired
output ahead of time. This allows the mill to cut, drill, and slot
more precisely and more repeatedly than by manually
controlling the milling cutter [7].
Milling is most often used within the aerospace industry
when particularly tight tolerances are required. This might
include brackets, bearings, wheels, fittings, and more.
LMD COMPARED TO TRADITIONAL
MACHINING METHODS
CASTING
Casting is a fairly straightforward process used to
produce detailed metal goods. Casting begins by creating a
mold which is the negative shape of the desired finished
product. This requires a prototype made from another
manufacturing method with which to make the mold. Next the
manufacturer must heat up the desired metal or metal alloy
until it reaches its liquid form. Then the molten metal is
poured into the mold and allowed to cool until the material
returns to its solid form, thus obtaining a new desired shape
Casting is generally used when a manufacturer wants to
make a lot of identical products. The aerospace industry
generally uses casts to cheaply produce non-stressed interior
components such as pedals, vents, switches, knobs, and more.
LMD has many potential advantages over traditional
machining methods, such as ease of product redesign and a
wider range of applications. LMD can be extremely flexible
and requires little tool up time or cost. However, to better
understand these advantages it is first important to understand
some techniques currently employed within the aerospace
industry.
MILLING
One such traditional machining method is milling. The
milling process begins with a solid mass of a desired material
that is larger than the finished product. The process of milling
focuses on precisely removing unwanted material until the
desired shape is achieved. Most milling machines, as pictured
in Figure 2 below, operate using a revolving cutting head,
called a “milling cutter” to remove excess material.
FORGING
Another common manufacturing technique is forging
where metal is pressed, pounded, or squeezed under immense
pressure to form desired shapes. Unlike casting, metal used in
forging may be heated but never reaches the liquid form. This
process usually involves extremely large and powerful
industrial hammers that can pound out objects by the tons per
square inch.
FIGURE 2 [5]
Close up of a milling cutter machining a slot
These milling cutters can be interchanged with different
designs for different purposes. Swapping out milling cutters
for those of different materials allows users to change the
hardness of the tool head and therefore work more effectively
with different materials. Exchanging milling cutters for those
of different shapes also allows machinists to perform different
cuts, such as boring, slotting, or drilling [6].
Many manufacturers today use a special form of milling
called Computer Numerical Control (CNC) milling. CNC
FIGURE 3 [6]
An industrial forge towers over its workers
The extreme compression forces applied helps produce
finished products with very tough and durable physical
properties [9]. Aerospace manufacturers often used forged
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components in places where components are subjected to high
stress. Some examples include gears, rotors, shafts, shrouds,
and cases.
Forging produces some of the strongest components, as
the hammering process hardens the final product. However,
this process requires extremely large and expensive industrial
machinery, often making it uneconomical on the small scale
and still very expensive on the large scale. Just like milling,
forging too is a time and labor intensive process. Also, forging
has the potential to be very dangerous to the person or people
working with it if all the necessary precautions are not taken.
While forging, one is essentially working with very large
containers of extremely hot metal. If by chance something
gets thrown out to the forge tower and comes into contact with
someone who is not fully protected, it can lead to a serious
injury.
LMD and other metallic printers find themselves
somewhere in the middle between all these manufacturing
techniques. Metallic 3D printing allows manufacturers to
rapidly produce finished metal products that are a wide
variety of materials and structures. The designing is done in
CAD programs, and if a manufacturer chooses to alter the
design, the printer can correct immediately without further
retooling or redesigning. Manufacturers using metallic
printing therefore have greater freedom to produce
individualized, custom products at little extra cost [10].
Production with LMD printers also does not rise in cost
as a component becomes more geometrically complex. LMD
fuses new material wherever the laser head is pointed, so by
directing the laser and supplying the powder feed, LMD can
move its laser in any direction desired. The only difference in
the creation of more complex structures is a slight increase in
the amount of time it takes to complete. However, it is still
much faster than using traditional or other types of additive
manufacturing. This has the potential to dramatically lower
the cost to manufacture geometrically complex parts such as
turbines, nozzles, and fittings [11].
Disconnecting complexity from cost also provides
designers a faster, cheaper way to rapidly produce and test
prototypes. LMD is particularly useful during prototyping
also because LMD printed prototypes are fully functional.
When the powder enters the melt pool beneath the laser, the
deposit is fusion-bonded to the substrate, meaning that the
product can no longer differentiate where new material meets
old material [3]. This amalgamation process between existing
material and new material is where LMD products get their
strength. By extension, this means LMD printers can alternate
seamlessly from prototyping to production, back to
prototyping, then production again, and so forth.
By reducing the time both to produce complex
components and redesign them, LMD offers aerospace
companies a more cost sustainable way to develop and
manufacture increasingly complex aircraft and spacecraft
components. Lowering the cost to produce these components
should also lower the cost of the final product. Especially
given the rising interest in space tourism, lowering the cost of
aircraft and spacecraft makes them more accessible to people
and companies who otherwise would never be able to afford
them.
ADVANTAGES OF LMD OVER
TRADITIONAL MANUFACTURING
The previously described techniques display certain
strengths within their respective areas, but LMD and metallic
3D printing in general offer a greater amount of flexibility and
efficiency than any of the traditional processes have on their
own.
While milling—specifically CNC aided milling—can
be a very precisely controlled process, it is also very time
consuming and involves a large amount of waste material.
Milling requires manufacturing to begin with a blank piece of
metal larger than the finished product, and if that product is
irregularly shaped, there can be a lot of excess waste material.
This material can often be recycled, but it requires an
additional time and energy expenditure. The time required to
mill products one by one also makes it a very expensive
process. The more geometrically complex the component, the
more expensive it becomes to machine.
As a result of the high cost and material expenditure,
milled components are generally reserved for high end
products. The inherent cost of milling drives up the cost of the
finished product and therefore often makes the process
unsustainable in the market of affordable products. In
industries such as aerospace where close tolerances are a
necessity, companies often continue using milling techniques
anyway. The resulting product, in this case an aircraft, ends
up being rather costly for the consumer.
Considering the time and cost of milling, many
manufacturers opt to cast their products instead, allowing
them to make as many products at a time as they have molds.
This, however, poses its own difficulties. For starters, all
castings require a mold to begin, which cannot be made
without first producing a prototype of the desired shape using
some other manufacturing method. Once this mold is made,
any changes to the desired product require making an entirely
new mold—an often time consuming process. In addition,
casted products are often not as strong as products produced
using other manufacturing processes, particularly when
compared to their forged counterparts. Lastly, it is difficult to
control metallurgical defects in the finished product such as
gas porosity and other inconsistencies.
The low cost of cast part often makes them ideal for
mass production. However, casting’s inflexibility when
making changes to the product coupled with the time required
to remold an updated product makes casting unsustainable
throughout research and development cycles within the
aerospace industry. Given that aerospace companies are
regularly updating and reengineering both existing and new
aircraft, casting becomes less than ideal large parts of the
aerospace industry.
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Lastly, LMD is not limited to strict manufacturing but
instead can also be used to coat and repair existing products.
LMD prints out of a mobile laser and nozzle head that can be
oriented in virtually any direction, allowing them to fuse
material to existing structures even if the surface is not flat.
As a result, LMD can be used on existing parts to refill cracks,
coat in a new material, or rebuild sheared off components
[12]. This becomes extremely useful for extending the service
lives of already expensive aircraft components and reducing
the amount of replacement parts needed. It also offers a costeffective way to add additional mechanical characteristics to
existing components. There many potential uses for LMD
printers regarding resurfacing and repair that will be
discussed with greater detail in a later section.
DMLS is the most widely used type of 3D printer, often
making it the most assessable. The majority of aerospace
companies such as Boeing and NASA that are beginning to
incorporate metal 3D printing into their products are currently
using this type of printer. This process can be very precise,
but often is not very efficient. DMLS printers generally leave
behind large amounts of excess powder. Even though the
excess powder can be recycled, it requires additional time and
energy to do so. Each time the printer finishes creating an
object, the printer must be prepared once again for the next
object by removing all the excess powder [15]. The use of a
powder bed as feeding material during DMLS also limits
these printers to printing in with individual cross sections
along a single axis. This can be problematic with more
complex and irregular shapes that often require users to build
in additional support structures while printing that must be
machined off later. Lastly, DMLS products are often rather
porous and lack the physical strength that LMD products
offer.
Though DMLS printers are more inexpensive as
compared to LMD, the inefficacy of the printing process
outweighs the lower price. The large amount of waste
material produced, coupled with the limitations of the strength
and the single axis, makes this type of 3D printing
unsustainable. These disadvantages can be particularly
impactful to the aerospace industry. One of the most
important qualities of an aircraft, especially in airplanes, is its
strength to withstand the unpredictable weather that pilots
encounter during flight. This lack of physical strength can
lead to many complications to many types of aircraft.
ALTERNATIVE METAL 3D PRINTERS
COMPARED TO LMD
Metallic 3D printing has been a rising interest of many
researchers over the last decade or so. As a result, there are a
few different methods to 3D print metals in addition to LMD.
Each one functions a little differently.
DIRECT METAL LASER SINTERING
One type of 3D printing process is called Direct Metal
Laser Sintering (DMLS), or sometimes referred to as
Selective Laser Melting (SLM). DMLS utilizes an entire bed
of fine metallic powder, which is struck by a high intensity
laser. The target area is then fused together to form an
extremely thin, solid 2D panel as seen in Figure 4 below.
Then, a new layer of powder is swept over the existing bed of
powder, and the laser repeats the process. Slowly, the
machine builds up the metal object layer by layer until it is
completed.
ELECTRON BEAM MELTING
Electron Beam Melting (EBM) is an additive
manufacturing process very similar to DMLS, but it uses a
focused electron beam to perform the fusing process rather
than a high intensity laser [15]. The electron beam fuses parts
of the powder bed into a continuous 2D shape and the object
is built up cross-section by cross-section. The electron beam
can be up to four times more energy efficient than the laser
used on DMLS printers, and it is possible have multiple
electron beams that work simultaneously on DMLS printers
to decrease the time needed to create the 3D objects [16].
EBM is another great alternative of 3D printing;
however it too has its limitations. This process is very similar
to DMLS, but by using electron beams to fuse material, it is
much more energy efficient. However, it suffers from many
of the same faults as DMLS such as excess powder waste and
is under the same limitations when bound to printing with a
powder bed. As a result, this printing process is also not very
sustainable in terms of reducing waste. LMD utilizes its
powder reservoirs more efficiently than either of these two
printers and boasts the ability to print along any axis and on
non-flat surfaces.
FIGURE 4 [13]
Key components within a DMLS printer
Once it is completed, there is often some final machining
needed to finish the metal object [14].
ELECTRON BEAM ADDITIVE MANUFACTURING
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XWB-97 engine front bearing housing stretching one and a
half meters in diameter and includes forty-eight aero-foil
subcomponents [18]. The aero-foil blades form the inner
turbine component as pictured in the photo below.
One last common 3D printing process is Electron Beam
Additive Manufacturing (EBAM). Like LMD, EBAM uses a
high intensity laser to fuse the metal together, and it doesn’t
need an entire bed of powder to fuse the metal together. The
main differentiating factor is that it uses one, or sometimes
two, solid metal wires rather than metal powder that are fed
out of the nozzle. The nozzle on EBAM printers are located
beside the laser, rather than being attached to the laser itself
[17].
EBAM remains a more advanced form of additive
manufacturing than either DMLS or EBM since it is not
bound by a powder bed. EBAM excels at being rather fast as
well, compared to DMLS and EBM. However, using metal
wire instead of powder as its feeding system leaves some
precision to be desired. It is rather difficult to control the rate
at which molten metal from the wires flows and binds, often
causing overflow, streaks, and drips. EBAM products exert
some of the same strong physical properties as LMD but
generally requires the most final machining out of any of these
processes. EBAM is still rather new on the market, and
perhaps will be further refined in the future. However, at the
moment, since it still requires significantly more final
processing than LMD, it is much less time and cost efficient
[15].
A key role in sustainability is achieving efficiency in
time. As compared to LMD, EBAM fails to do so. This
additional process of heating the metal wire into an almost
liquid form leads to an increase of time as it takes to produce
3D structures. Also, the lack of precision with using metal
wires as opposed to powder can lead to an increase time since
final machining may be needed to finish the structures to the
manufacturer’s standards. As a result, this excess time can
cause companies within the aerospace industry to lose money
if they cannot produce enough products to meet demand.
FIGURE 5 [19]
Trent XWB-97 Aircraft Engine
These aero-foil subcomponents were manufactured
using a combination of LMD as well as EBAM 3D printing
methods. Currently, these components are still considered
prototypes and are not yet present on production engines but
Rolls Royce stated that tests with these components would
provide insight into the possibility of integrating additive
manufacturing methods in the future [19].
GE BEGINS PRODUCTION OF FUEL NOZZLES
Rolls Royce is not the only company currently utilizing
metallic 3D printers though. In 2016, GE opened a new
assembly plant in Indiana designed to manufacture the
world’s first passenger jet engines fitted with 3D printed fuel
nozzles as pictured below.
CURRENT APPLICATIONS WITHIN THE
AEROSPACE INDUSTRY
Aircraft, such as planes and rockets, today are an
amalgamation of parts made from a wide variety of materials
to perform a wide variety of functions. Consequently,
manufacturing many of these components with the necessary
quality and precision is often a costly process in both time and
resources. Naturally, companies manufacturing aircraft
component have been searching for more efficient ways to
produce geometrically complex components and, for some,
LMD has been the solution.
ROLLS ROYCE GOES BIG
One such company to recently adopt LMD
manufacturing processes is the aerospace division of Rolls
Royce. In late 2015, Rolls Royce flew an Airbus A380 with
the largest 3D printed aero-engine component ever, a Trent
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commercial aircraft production programmes” [18]. Though
this particular statement does not specify how many of these
parts are metal printed versus printed with polymers, the
company’s growing acquisition of metallic 3D printers
suggest that a fair number of these parts could be metallic 3D
printed.
NASA EXPLORES METALLIC 3D-PRINTING AS
WELL
Currently, NASA’s primary method of metal
manufacturing consist entirely of mills, lathes, welding
equipment, and sheet metal equipment. Using these current
methods, NASA has to manually perform physical alterations
to the different types of metal they use. They have many
machines that help aid the workers, but it is a very hands-on
process that includes rolling, cutting, and forming the metal
into its desired shape and size [23]. This process can be very
effective, but it is very time-consuming.
Recently, however, NASA has been experimenting with
various types of 3D metal printing. In particular, they have
used Selective Laser Melting (SLM), an additive
manufacturing process very similar to DMLS, to create
individual parts to build a fully functional engine. Throughout
various tests, the engine was capable of producing up to
20,000 pounds of thrust [24]. Specifically, NASA created one
of the most complex engine parts ever made with a 3D printer:
a turbopump as shown in Figure 7.
FIGURE 6 [20]
3D printed fuel nozzle present in GE’s LEAP engine
These engines using 3D printed fuel nozzles, named
“LEAP”, are present on the Airbus A320neo and already
became GE’s best-selling engine with six thousand confirmed
orders from twenty different countries [20]. Boeing has also
designed two additional versions of the LEAP engine for the
Boeing 737 MAX and COMAC C919. Currently however,
these production lines appear to be using mainly DMLS
printers to produce the fuel nozzles, but GE claims to be using
the new facility as a testbed for many additive manufacturing
processes including LMD [21].
BOEING EXPERIMENTS WITH METAL 3D
PRINTING
In a recent statement, Boeing announced that they, too,
are developing new production facilities to exploit additive
manufacturing. As stated by Leo Christodoulou, Boeing’s
Additive Manufacturing Strategy Leader, “We are currently
working with machine providers and putting building blocks
in place to enter into full scale production by the fourth
quarter 2017” [22].
According to the statement, Boeing has yet to finalize
which additive manufacturing techniques they would
implement into full scale production. However,
Christodoulou emphasized that Boeing was evaluating “all
categories of additive metals” including Direct Metal
Deposition systems (another term for LMD) [22].
Boeing is no newcomer to additive manufacturing
though. They have been researching and developing 3D
printers as early as 1997 and claiming that they already have
approximately 50,000 3D printed parts installed on their
aerospace products [22]. Boeing also boasts that, “these
include 3D-printed parts on 10 different military and
FIGURE 7 [25]
NASA’s 90,0000 rpm capable turbopump
According to NASA, “The turbopump is a critical rocket
engine component with a turbine that spins and generates
more than 2,000 horsepower--twice the horsepower of a
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NASCAR engine.” Additionally, the turbopump was able to
reach up to 90,000 rotations per minute (rpm) throughout a
series of tests performed on it [24, 25].
with the help of NASA, wants to use this rocket to eventually
transport people into space [28]. Following the success of
their first implementation of 3D printed parts, SpaceX is
interested in exploring the different types of additive
manufacturing such as LMD for use in other future products
[27].
SPACEX TAKES 3D PRINTING TO ANOTHER
LEVEL
Over at SpaceX, Elon Musk, the company’s founder and
CEO, really likes to push technology forward. Particularly, on
January 6, 2014, SpaceX had successfully launched a rocket
with a 3D printed Main Oxidizer Valve (MOV) as seen in
Figure 5 below.
FUTURE APPLICATIONS OF LMD WITHIN
THE AEROSPACE INDUSTRY
One of the great advantages of using LMD is that it can
build upon whatever surface is already present. Powder bed
printers, such as DMLS and EBAM for example, must print
along flat cross sections. An LMD printer, though, can deposit
material on any type of surface such as a round surface. This
becomes extremely useful when trying to repair metal
components such as turbines and fuel nozzles. LMD printers
are perfectly capable of starting with a broken component, no
matter what shape, and build up newly deposited material
layer by layer until the desired fix is achieved. Deposit layers
may range between .005 to .04 inches thick and can be used
to perform repairs such as filling cracks, coating components,
or even rebuild entire missing structures [29].
This ability would be extremely useful within the
aerospace industry, particularly because aerospace
components are so often complex and expensive to
manufacture. For example, metal parts such as turbines and
engine parts and encasings can take a lot of time creating and
shaping with traditional manufacturing methods. It would
therefore be more economical to repair parts and extend their
service life, rather than procuring new parts since doing so is
expensive time consuming. In many cases, particularly with
older aircraft, the original equipment manufacturer may no
longer be needed, making replacement parts no longer an
option. LMD repair would therefore offer a cost alternative to
restore parts to their original functionality.
In addition, LMD only involves a small heat affected
zone, where powder is deposited in the melt pool beneath the
laser. Conventional welding processes, often used to repair
metal components, involve rather large and deep heat affected
zones around the weld. This stress can cause distortions or
alter the physical properties of the component, posing new
weaknesses such as brittleness in the component. LMD’s
small heat affected zone minimizes this stress, maintaining
the integrity of the foundation object [30]. New material laid
down by an LMD printer exhibits virtually the same physical
characteristics as the existing material, making LMD repairs
strong and durable
Lastly, LMD can also be used to coat components. This
can be used simply to repair worn down finishes or add
entirely new finishes as means of imbuing new physical
properties to the surface of an object [2]. This is also
extremely helpful within the aerospace industry, given the
immense stress many parts are subjected to and the cost of
many refinishing procedures. Turbines within a jet engine, for
FIGURE 8 [26]
The Space X MOV
In flight, the MOV performed flawlessly, even while
handling high pressure liquid oxygen, extreme temperatures,
high vibration. The MOV is an essential part of the rocket’s
engine. In an engine, liquid oxygen must travel to the main
combustion chamber for the engine to function properly, and
the MOV controls this process. A valve can lead to
catastrophic damage if it malfunctions during flight [27].
Using a metal 3D printer similar to DMLS, Musk and
SpaceX were about to create the MOV body in less than 2
days. Normally, using traditional manufacturing such as
casting, it would take months to build the same part [26]. In
addition, Space X reports that the 3D printed valve body had
superior strength, ductility, and fracture resistance than a
traditionally cast part. Therefore, going into the future
SpaceX has approved the printed MOV to be used
interchangeable with cast parts on all future Falcon 9 flights.
The rocket, named Falcon 9, is one of the 2 stage rockets
designed to transport satellites into space. Musk ultimately,
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example, are subjected to incredible temperatures and are
under great force. Consequently, these turbines must be
replaced whenever they fall out of specification. Being
geometrically complex, they are expensive to manufacture.
However, LMD would allow companies to coat and recoat
turbines with titanium or any desired allow to protect turbines
from wear and exhibit whichever thermochemical properties
are desired.
component repair, surface coating, and more. Traditional
manufacturing processes may do one or a few of these things
well, but fall short when it comes to the others. Milling, for
instance, is great at prototyping but slow when it comes to full
time production. Casting on the other hand is slow to tool up,
but once the molds are made it is one of the fastest
manufacturing methods. LMD is perhaps to best of both
worlds, fast to develop prototypes with and efficient to
manufacture. This allows for a quicker and more efficient
production of metal parts used on different types of aircraft.
This can be especially more time-efficient for creating metal
parts such as turbines that can be very time-consuming to
produce due its complex structure.
These of course are traits of additive manufacturing in
general, yet LMD still retains notable advantages over
alternative metal printers. It does not produce nearly the same
amount of waste powder as powder bed style printers such as
DMLS and EBM. But at the same time, it also prints in more
flexible directions than said powder bed style printers while
being more precise than wire fed systems like EBAM. These
many advantages over other types of manufacturing and
additive manufacturing is what makes LMD an incredibly
sustainable process.
With all these traits combined, LMD finds a natural
home within the aerospace industry. Multidirectional printing
allows LMD to be much more efficient at making complicated
components such as turbines, valves, and other oddly shaped
parts often found within aerospace projects. At the same time,
LMD’s same characteristics also make it well suited for the
prototyping and development side of aerospace development.
Nonetheless, LMD has some ways to go before becoming
anything close to an aerospace industry standard. Yet the
future is ever evolving and it would not at all be a surprise if
LMD moves to the forefront of additive manufacturing.
SUMMARY OF LMD
The invention of the plastic 3D printer revolutionized
prototyping in many industries. Now the development of the
metal 3D printer poses to revolutionize prototyping again in
addition to manufacturing as a whole. Specifically, in
aerospace engineering, 3D printing with metal opens many
new doors. LMD is a very efficient process in both time and
money. It prints in multiple axis to finish the job quicker, and
it uses powder which aids in its precision and resource
management throughout the printing process.
There are a wide variety of uses available for LMD. But
by having this technology at their disposal, aerospace
companies such as Boeing and NASA can replace many of
the manufacturing processes that are currently in use. LMD
allows them to be able to produce and repair metal
components without the need of using older manufacturing
techniques such as milling, casting, and forging.
LMD is also superior when compared to other additive
manufacturing techniques. When compared to other
techniques such as DMLS, EBM, and EBAM, it is much more
efficient and stronger. Although DMLS and EBM can rival
LMD in precision, the extra time needed for final processing,
machining, and cleaning up excess waste material makes
LMD the more sustainable option overall. LMD offers a more
cost efficient manufacturing process and will likely decrease
the cost of expensive aircraft and spacecraft in the future.
Decreasing the cost of such complex machines would make
them more available to a larger market. In addition, decreased
energy and material consumption may lessen the impact of
manufacturers on the environment. Currently however, total
aerospace manufacturing is a relatively small fraction of
manufacturing worldwide so this environmental impact may
be difficult to identify. That being said, LMD will likely be
applied outside of the aerospace industry as well and has the
potential to transform many fields of manufacturing into more
cost effective, resource efficient, and therefore more
sustainable processes.
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LMD is still a newcomer to the field of additive
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8
Caleb Foglio
Nathan Bretscher
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ACKLNOWLEDGEMENTS
We would like to thank Kelly Larson for giving us
advice while writing this paper. We would also like to thank
our writing instructor, Nancy Koerbel, for providing us with
comments on how to improve our paper. Lastly, thank you for
taking the time to read our conference paper.
10

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