Recent Advancement of Rapid Prototyping in Aerospace Industry- A Review

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Recent Advancement of Rapid Prototyping in

Aerospace Industry- A review Mahendrakumar Ramamoorthy, Department of Industrial and systems engineering,

The State University of New York at Buffalo, Buffalo, United States of America

[email protected]

December 2013

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Abstract:

Today the industrial sector is highly competitive and increasingly companies are attaching

greater importance to the need to differentiate their product and service offerings in order to remain

profitable. Typically, firms are adding new technologies to their products to differentiate, forming

alliances with their customers, adding service features to their manufactured product offerings,

reducing time to market for new products, reducing the number of suppliers and forming longer-

term relationships and alliances with those that remain, expanding their product range, and

reducing their cost base to become the lowest cost producer. Rapid prototyping technologies have

the potential to contribute something to the achievement of most, if not all these actions.

Though Rapid Prototyping Techniques find vast areas of application, we confine our paper

only within aerospace sector. This review paper deals with different types of Rapid Prototyping

methods used particularly in aerospace industry, their advantages and limitations. The scope of

this paper is extended to their current achievements and future of RP in aerospace sector.

Keywords: Rapid Prototyping, Stereo lithography, Selective Laser sintering, 3D printing, Fused

Deposit Modelling, Laminated Object Manufacturing

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1. Introduction:

The nature of the aerospace industry demand that all parts are as reliable as they possibly

can be. No corners can be cut when it comes to the design and manufacture of aerospace parts

which is why the best processes available need to be implemented. The complexities involved with

aerospace design make additive manufacturing the obvious choice as other forms of machining

simply cannot meet the required standards. Rapid prototyping has emerged as a key enabling

technology with its ability to shorten product development and manufacturing process that

produces a physical prototype from a 3D cad model layer by layer which is also called as layer

manufacturing.

It aims to produce prototype relatively quickly for visual inspection, ergonomic evaluation,

and form fit analysis and as master pattern for product. The application of R.P to the product

manufacturing process has shown a 60% decrease in lead time over traditional method with the

various advantages that R.P technology promise R.P has begun to make its way in to the

aeronautical industry and is set to have profound implication. The Northron Grunman global hawk,

it is just one of many vehicles which depend on R.P for its development. Some of the desirable

features which fits the RP into aerospace sector are its capability to test new materials, ability to

build geometrically complex structures, and elimination of higher tool cost of low volume

production. Here we will discuss the different types of RP techniques available in market and its

achievements.

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2. Rapid Prototyping (RP):

Rapid Prototyping can be defined as a group of techniques used to quickly fabricate a scale

model of a part or assembly using three-dimensional computer aided design (CAD) data. Additive

Layer Manufacturing or 3D printing is usually labored for fabrication or assembly. A scanning

device is used to create 2D slice geometry or 3D models are created using the CAD workstations.

This form the first step in RP. For RP this data must represent a valid geometric model; namely,

one whose boundary surfaces enclose a finite volume, contain no holes exposing the interior, and

do not fold back on themselves.

CAD post-processors will approximate the application vendors’ internal CAD geometric

forms (e.g., B-splines) with a simplified mathematical form, which in turn is expressed in a

specified data format which is a common feature in Additive Manufacturing: STL (stereo

lithography) a de facto standard for transferring solid geometric models to SFF machines. To

obtain the necessary motion control trajectories to drive the actual SFF, Rapid Prototyping, 3D

Printing or Additive Manufacturing mechanism, the prepared geometric model is typically sliced

into layers, and the slices are scanned into lines [producing a "2D drawing" used to generate

trajectory as in CNC`s tool path], mimicking in reverse the layer-to-layer physical building

process.

The professional literature in RP contains different ways of classifying RP processes.

• Liquid-based RP systems – the initial form of material is in liquid state and, by a curing process,

the liquid is converted into solid state; the system includes: 3D Systems’ Stereo lithography (SLA),

Light Sculpting, Rapid Freeze and Two Laser Beams;

• solid-based RP systems – the initial form of material is in solid state, except for powders (wire,

roll, laminates, pellets); this system includes: Stratasys ‘Fused Deposition Modeling (FDM), 3D

Systems’, Multi-Jet Modeling System (MJM) and Pares lamination Technology (PLT);

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• Powder-based RP systems – the initial form of material is powder; the system includes: 3D

Systems’ Selective Laser Sintering (SLA), Precision Optical Manufacturing’s Direct Metal

Deposition (DMD) and Z Corporation’s Three Dimensional Printing (3DP).

However, one representation based on German standard of production processes classifies

RP processes according to state of aggregation of their original material and is given below.

3. Selection of Appropriate RP technology:

The first rapid prototyping technique stereo-lithography was developed by 3D system of

Valencia, California, USA in 1986 since then number of different R.P technique have been

developed till date. Over 20 different types of RP methods are available in market for parts

manufacturing. But not all the technologies are acceptable in aerospace industry and only few

methods are preferred here. Fraunhofer Institute for Manufacturing Engineering and Automation

(IPA) found that the quality function deployment (QFD) approach can be used for selecting the

most appropriate R.P technology. It begins by matching customer requirement, which on turn

match with necessary corresponding production requirement, and so on, to ensure that the

customer needs are satisfied. The key benefit of implementing QFD is that engineering knowledge

is retained in systematic manner so that it can be easily applied to future similar designs. The whole

QFD procedure uses a series of matrices called house to express the linkage between inputs and

outputs of different phases of development. Surveying the different layer based technology

platforms that are commercially available today, only the followings are practically applicable in

aerospace industry

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1. Stereo Lithography (SLA)

2. Selective Laser Sintering (SLS)

3. Fused deposition modelling (FDM)

4. Laminated Object Manufacturing(LOM)

5. Three Dimensional Printing(3DP)

Here we will discuss briefly about each technique’s process, their advantages and also the

limitations.

3.1. Stereo Lithography (SLA)

The Most accurate machine available among all other RP technique and the first

commercially accepted RP process is the Stereo Lithography. It was invented by Charles Hull in

1987 who worked for 3D systems. This additive process is based on selective polymerization of a

photosensitive liquid resin using ultraviolet light. The process begins with by filling a vat with

liquid photo curable resin acryl-ate and placing it in the elevator table. A UV Helium-Cadmium or

argon laser beam then traces a single layer cross section onto the surface of a vat of liquid polymer.

Due to the absorption and scattering of beam, the reaction only takes place near the surface and

voxels of solid polymeric resin are formed.

The photo polymerization Process happens (linking small molecules known as monomers

into chain-like larger molecules known as polymers) which causes the polymer to harden precisely

at the point where the ultraviolet light hits the surface. The Beam is positioned and moved in

horizontal X and Y directions of the pre-defined boundary and it is controlled by a galvanometer

driven mirrors. The laser scans the first layer and platform is then lowered equal to one slice

thickness (typically 0.05 mm to 0.15 mm (0.002" to 0.006")) and left for short time (dip-delay) so

that liquid polymer settles to a flat and even surface and inhibit bubble formation.

Then, a resin-filled blade sweeps across the part cross section which recoats it with fresh

material. On this new liquid surface, the subsequent layer pattern is traced; adhering to the previous

layer, in this way, the model is built layer by layer from bottom to top. When all layers are

completed, the prototype is about 95% cured. Once the complete part is deposited, it is removed

from the vat and then excess resin is drained. It may take long time due to high viscosity of liquid

resin. The green part is then post-cured in an UV oven after removing support structures.

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Capacity and Materials Used:

The vat which holds the liquid polymer determines the size limit of the prototype. The

Maximum dimension of a part that can be built is approximately 50×50×60 cm (20"×20"×24") but

some machines like Mammoth stereo lithography machine (which has a build platform of

210×70×80 cm), are capable of producing single parts of more than 2 m in length.

The accuracy achieved is about 0.1% of the overall dimension and deteriorates with larger

sizes but no more than 0.5%. The layer thickness is between 0.004 and 0.03 in.

Some of the commercially available polymers for SLA process are Accura 60 Plastic,

Accura 55 Plastic, Accura 50 Plastic, Somos 11122 Transparent Plastic, SL5240 Polypropylene-

like resin, SL7520 high strength resin, SL7870 Polycarbonate-like resin, Somos Raven 7620.

Advantages:

Stereo lithography is the ideal choice for Form and Fit testing of new designs, Functional

parts for special projects , Architectural models and one-offs, Form and Fit testing of new

designs ,Testing of new designs or reverse engineered parts, Investment Casting patterns

for Quick Turn cast metal parts ,Limited run production parts.

Achieving High accuracy in industrial standard.

Bluestone parts resist deformation even under heavy loads and Resists temperatures up to

250°C, making it suitable for tooling or other demanding applications.

Suitable for thin-walled parts that require the stiffness of high performance engineering

parts

Improves/enhance demanding applications: wind tunnel, soft tooling and injection mold

tooling.

Consistent mechanical properties, even on long builds

Good Surface Finish

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Limitations:

Support structures always needed. Removal of support structures can be difficult.

Requires post-curing.

Limited materials (Photo polymers).

Some war page, shrinkage and curl due to phase change.

3.2. Selective Laser Sintering (SLS)

Selective Laser Sintering (SLS) was developed and patented by Dr. Carl Deckard and

academic adviser, Dr. Joe Beaman at the University of Texas at Austin in the mid-1980s, under

sponsorship of DARPA. It serves as an alternative additive manufacturing process for the liquid

curing system. SLS uses a high power laser beam (for example, carbon dioxide laser) to sinter

successive layers of powder spread on a layer instead of liquid. The powder is metered in precise

amounts and is spread by a counter-rotating roller on the table. A laser beam is used to fuse the

powder (by preheating the powder to a temperature just below its melting point) within the section

boundary through a cross-hatching motion. The table is lowered through a distance corresponding

to the layer thickness (usually 0.01 mm) before the roller spreads the next layer of powder on the

previously built layer. The un-sintered powder serves as the support for overhanging portions, if

any in the subsequent layers.

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Capacity and Materials Used:

SLS models can be built up to: 22" x 22" x 18" (550mm x 550mm x 460mm). Larger

models of virtually any size, can be sectioned and assembled upon completion.

Layer Thickness: 0.004" - 0.006" and SLS & LS: Accuracy: +/- .005" for the first 5 inches,

+/- .001" inch per inch thereafter.

SLS can make use of relatively wide range of commercially available powder

materials such as nylon(Dura Form, Dura Form PA Nylon) or polystyrene(Dura Form), metals

including steel, titanium, alloy mixtures, and composites(Wind Form XT) and green sand.

Advantages:

Selective Laser Sintering (SLS) is the ideal choice for Prototypes that require material

properties that closely replicate injection-molded parts. Depending on the material, up to

100% density can be achieved with material properties comparable to those from

conventional manufacturing methods.

The main advantage is that the fabricated prototypes are porous (typically 60% of the

density of molded parts), thus impairing their strength and surface finish.

No post curing required.

Variety of materials. Mechanical properties of Nylon & Polycarbonate parts are used and

hence Excel in load bearing applications at higher temperatures.

Fast build times. Eliminate painting by using black color.

Unlike some other additive manufacturing processes SLS does not require support

structures due to the fact that the part being constructed is surrounded by un-sintered

powder at all times, this allows for the construction of previously impossible geometries.

Compatible with autoclaves, low-temperature furnaces, and vacuum plaster casting

methods.

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Limitations:

Rough surface finish.

Mechanical properties below those achieved in injection molding process for same

material.

Material changeover difficult compared to FDM & SLA.

Many build variables, complex operation.

3.3. Fused Deposition Modeling (FDM)

Another famous additive manufacturing technology in market is Fused Deposition

Modelling (FDM).It was developed by S. Scott Crump in the late 1980s and this process was first

commercialized by Stratasys in 1990. The FDM machine use a CAD model to produce a physical

prototypes by taking the STL file created by the CAD model and first converting it into an SML

file which generate a tool-path to maneuver for each layer or slice to deposit material. The slice

thickness can be set manually to anywhere between 0.172 to 0.356 mm (0.005 to 0.014 in)

depending on the needs of the models. The fused deposition modelling (FDM) process creates

parts by extruding material (normally a thermoplastic polymer, ABS - engineering and medical

grade - plastic, Polycarbonate and investment casting wax) in a cross-hatching fashion. The

Machine consist of a heating chamber which is a 90-degree curved elbow wrapped in a heating

element, which serves as a melting area for the material and to change the direction of the filament

flow so that material is extruded vertically downward. The head is moved in the horizontal X and

Y directions for producing each layer through zigzag movements. The material solidifies in 0.1s

as it is directed on to the workplace. Once a layer is complete the supporting table is moved in the

Z Direction for building the next layer. The FDM process does not need support to produce part

in most cases as head forms a precision horizontal support in mid-air as it solidifies. But for

overhanging parts, a support may still be required, which can be manual or, water soluble supports

to reduce part distortion.

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Capacity and Materials Used:

ABS models can be built up to: 36" x 24" x 36" (914mm x 610mm x 914mm). Larger

models of virtually any size, can be sectioned and assembled upon completion. ULTEM 9085,

PC and PC/ABS models can be built up to: 36" x 24" x 36" (914mm x 610mm x 914mm).

Larger models of virtually any size, can be sectioned and assembled upon completion. The

FDM systems have evolved through several models, beginning with the original 3D Modeler,

a floor unit, and progressing through the various "desktop units", including the 1500, 1600,

1650, 2000, 8000, and Quantum.

Accuracy: +/- .005" for first 5 inches, +/- .0005" inch per inch thereafter (ABS). Same part

repeatability (ABS) +/- .001". In standard res mode, minimum recommended wall thickness is

0.032", in high res mode 0.020". High Speed Slice: 0.013" (900mc builds only), Standard

Layer Slice: 0.010" (default build style), High Resolution Slice: 0.007"

Commonly used FDM materials are ABS, ABS/F1, BS/PC Blend, polycarbonate, Ultem

9085. All the materials are non-toxic and can be in different colors. There is minimum material

wastage in the method.

Advantages:

No post curing.

Variety of materials. Easy material changeover.

Office environment friendly. Low end, economical machines.

The advantage of FDM is the material capacity to handle heat and other demanding product

tests. It is a feasible option for both rapid prototyping and rapid manufacturing, producing

parts that are both accurate and durable.

It is able to fabricate fully functional parts that have 85% of the strength of the actual

molded part, because of this reason it is highly applicable for Aerospace and Aviation

industries.

Limitations:

Not good for small features, details and thin walls.

Surface finish.

Supports required on some materials / geometries.

Support design / integration / removal is difficult.

Weak Z-axis.

Slow on large / dense parts.

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3.4. Laminated Object Manufacturing (LOM)

The first commercial Laminated Object Manufacturing (LOM) system was developed by

Helisys of Torrance, CA in 1991. A manufacturing process that uses a carbon-dioxide laser to

create successive cross-sections of a three-dimensional object from layers of paper with a

polyethylene coating on the backside. The first step is to create a base on which the paper can

attach itself to. This is done by placing a special tape down onto the platform. A sheet of paper is

fed through with the aid of small rollers. As the paper is fed through, a heated roller is used to melt

the coating on the paper so that each new layer will adhere to the previous layer. The carbon-

dioxide laser then cuts the outline of the cross-sectional pattern into the top layer of paper. Once

the laser is done cutting the pattern, it creates a border around the build that contains the desired

part. This enables the part to stay intact as each new layer is created. Once the border has been cut,

the laser then proceeds to create hatch marks, or cubes that surround the pattern within the border.

The cubes behave as supports for the part to ensure that no shifting or movement takes place during

the entire build. When the build is completed, the part, attached to the platform, needs to be

removed from the LOM. Depending on the size of the part, the block to be removed may take more

than one person to remove the build from the LOM. After the part has been successfully removed

from the LOM, it must then be removed for the actual platform. Again this may take the work of

more than one individual. A wire is used and placed between the part and the platform to "cut" the

part away from the metal platform.

The border, or frame of the part is then removed. The next step involves removing the

supports. Often times the supports can be removed from simple shaking the part; other times it is

necessary to use a chisel to pry the cubes away from the part. When all of the cubes have been

removed, the unfinished part is sanded down and a lacquer is used to seal the part. Being that LOM

parts are made for paper, humidity and temperature affect the structure and composure of the part

if it is not coated; hence, the lacquer serves as a protective measure. The LOM is very useful in

manufacturing large parts quickly.

Capacity and Materials Used:

There are currently two sizes of LOM’s available LOM 1015 – 10”x15”x14” (build area)

and LOM 2030 – 20”x30”x24”.

A precise X-Y positioning table is used to guide the laser beam resulting in production of

accurate parts. Accuracy of 0.010" is easily achieved regardless of the size of the part.

Variety of Materials like Paper, plastics, composites, and ceramics can be used in the LOM

systems. Commercial availability of various sheet materials allow the users to vary the type and

thickness of the manufacturing material for their specific applications. Paper is the simplest and

least expensive material, and it produces rigid and durable parts which have properties similar to

plywood. Plastic films are more expensive and they result in parts which are more flexible.

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Advantages:

Speed--The LOM process does not convert liquid polymers to solid plastics nor does it

convert plastic powders into sintered objects, but instead it uses existing solid sheet

materials which are glued using a hot roller and cut with a laser beam.

Unlike competitive technologies such as Stereo lithography and Selective Laser Sintering,

the laser in the LOM process does not have to scan the entire surface area of each cross-

section, rather it only has to outline its periphery. Therefore, parts with thick walls are

produced just as fast as those with thin walls.

The LOM process is especially advantageous for production of large and bulky parts which

are often encountered in the aerospace and automotive industries. The reason for this

unique advantage is the fact that the core manufacturing material does not need to be

formed since the laser merely determines the geometrical shape by removing excess

material.

Simplicity--The simplicity of the LOM process and systems allow them to be practical

extensions to many manufacturing and design environments. LOM machines can be

thought of as peripheral devices to a CAD workstation, allowing any designer to output

any design directly to an LOM system. The need to create additional support structures is

completely eliminated with the process; something which is essential for competitive stereo

lithography systems.

The LOM process is quite straightforward and the user does not need to have any specific

knowledge of chemistry, physics, mechanics or electronics in order to operate the machine.

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The systems are designed using standard electromechanical components which makes

them easy to maintain and troubleshoot.

Limitations:

Need for decubing, which requires a lot of labor

Emission of smoke or fumes

Can be a fire hazard

Finish, accuracy and stability of paper objects not as good as materials used with other RP

methods

3.5. Three Dimensional Printing (3DP):

Three Dimensional Printing (3DP) technology was developed at the Massachusetts

Institute of Technology and licensed to several corporations. The process is similar to the Selective

Laser Sintering (SLS) process, but instead of using a laser to sinter the material, an ink-jet printing

head deposits a liquid adhesive that binds the material. The 3D printing process begins with the

powder supply being raised by a piston and a leveling roller distributing a thin layer of powder to

the top of the build chamber. A multi-channel ink-jet print head then deposits a liquid adhesive to

targeted regions of the powder bed. These regions of powder are bonded together by the adhesive

and form one layer of the part. The remaining free standing powder supports the part during the

build. After a layer is built, the build platform is lowered and a new layer of powder added, leveled,

and the printing repeated. After the part is completed, the loose supporting powder can be brushed

away and the part removed. 3D printed parts are typically infiltrated with a sealant to improve

strength and surface finish.

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Capacity and Materials Used:

Max part size of 59.00 x 29.50 x 27.60 in and in feature size of 0.008 in can be built with

3DP with a Min layer thickness 0.0020 in and Tolerance of 0.0040 in.

Ferrous metals such as Stainless steel; Non-ferrous metals such as Bronze; Elastomers;

Composites; Ceramics.

Advantages:

Cost effective solution for small to medium size parts in shortest lead time

Parts have little flexibility, makes them suitable for limited snap features or thin wall

flexible features

Environmental exposure do not alter the size of the part or its features.

Ideal for general purpose parts exposed to temperature, water and many chemicals.

High level of finish can be achieved by sanding and other post processing techniques.

These parts can be further machined, polished or painted.

Limitations:

3DP parts have a ribbed and little rough appearance due to layering beads of plastic.

Not suitable for extensive functional testing

Could be a slow process for large build volume parts.

4. Factors specific to Aerospace Industry:

Aerodynamic structure stability is the important criteria when any part is developed in

aerospace industry. For an air born structure like the aircraft the basic load which is continuously

acting on it is the lift and drag force and they directly affect the internal structure of an aircraft.

Lift, L = Ci * 0.5(ρv2s)

Drag, D = Cd * 0.5(ρv2s)

When the velocity, density, surface area and co-efficient of lift are higher the lift and drag

forces tends to be higher and thus the amount of force which the aircraft has to withstand is very

large from material point of view. But we cannot expect a higher values for above said properties

for the parts manufactured using he rapid prototyping technology as it is at its early stage. It cannot

replace the traditional aircraft manufacturing process as of now. The table below show the different

material properties used in R.P technology.

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5. Recent improvements & achievements of RP in Aerospace Industry:

Considerable improvements have been made in using Rapid Prototyping for aerospace part

manufacturing. Layer-build technology was successfully implemented on the F/A-18 by the US

Navy. Using Nylon11 by SLS for a low rate production application, similarly a series of parts that

formed the ductwork were built on a Vanguard SLS machine to check the flightworthiness by BAe

(British aerospace). After a series of testing, re-building of parts with different machine build

parameters and implementing post processing techniques, the parts were eventually certified as

flightworthy. Design Verification of an Airline Electrical Generator, Engine Components for

Fanjet Engine, and Prototyping Air Inlet Housing for Gas Turbine Engine Fabrication of Flight-

Certified Production Castings were also done successfully.

Companies have an increasing number of printing techniques to choose from, such as

electron-beam melting, which, like SLS, makes production-grade aerospace parts. They can also

print with many materials, including titanium, ceramic, and resin. Arcam, a 3-D–printer

manufacturer in Sweden, is working with select labs to develop new materials and substantially

expand its portfolio. As a result, companies are now using 3-D printing to create working parts,

not just prototypes.

For now, those parts aren't critical aircraft components. For example, the new Boeing 787

Dreamliner includes 30 or so printed components—a record—but most of them are air ducts or

hinges. That, too, could change. In November, NASA started printing parts to test for its next

heavy-lift rocket. One company, DIY Rockets, went even further: It launched a contest to develop

an open-source, 3-D–printable rocket engine. Last fall, students at the University of Virginia

printed almost all the components of an operational UAV, including the 6.5-foot wingspan, and

flew it around an airfield.

Property

Method

Materials

Used

Tensile

Strength

(Psi)

Tensile

Modulus

(Ksi)

Elongati

on at

Break

(%)

Flexur

al

Strengt

h

(Psi)

Flexura

l

Modulu

s

(Ksi)

Impact

Strengt

h

(Ft-

lb/in)

Hardne

ss(Shor

e D)

SLA

(SL5170) Polymer 8700 575 12 15600 429 0.6 85

SLS

(Protoform

)

Ceramic,

Wax and

Alloy 7100 408 6 _ 625 1.25 _

FDM

(ABS)

Wax and

Polymer 5000 360 50 9500 380 2 105

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Similar achievements is the wind tunnel model of the European tilt rotor realized by the

Rapid Prototyping Department of CRP Technology during the first months of the 2007. Wind

tunnel Testing is one of the major part in the engine rotor design in any aerospace sector and this

achievement helped the industry in realizing the worthiness of RP. It proved that the RP models

can withstand in high profile testing environment. The wind tunnel model of the European tilt rotor

realized by the RP department of CRP technology by using wind form material. The model was

completed and tested in a very short interval of time with excellent result and high performing

mechanical and aerodynamic properties. Thus Layer-build technology is successfully

implemented for a low rate production application and early design criteria .The benefits, which

included design flexibility, no tooling and just-in-time delivery, all contributed to the end customer

accepting and allowing this technology to be implemented in aerospace industry.

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6. Future of RP Technology in Aerospace Industry:

Even though the RP technology find vast area in the aerospace industry, its application is

limited primarily due to the following three factors.

I. Materials used for parts production

II. Geometric Limitation of the equipment

III. Parameters related to process

The very first limitation of RP in Aerospace industry is the lack of an appropriate range of

materials for its application. This made authorities to impose very stringent quality measures for

the usage of materials in real time parts manufacturing in aerospace industry. Currently low

volume application products are produced with acceptable materials like epoxy resin, composite

materials and sintered nylon and those products are often good enough for

Evaluation of components by visualization

Evaluation of design variations

Estimation of the surface quality of the aircraft model

Evaluation of the aircraft interior

Ergonomic valuation with the aid of virtual reality.

Materials like flame retardant nylon, exotic metal such as titanium and high order engineering

grade materials are under R&D and they can innovate the future of R.P in Aerospace industry. All

vehicle programmes – manned, unmanned, civil and military could benefit from rapid prototyping.

All system builders – large and small - can use rapid prototyping to reduce their exposure to risk

considerably.

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7. Conclusion:

Rapid Prototyping is proving to be a successful method starting from early design phase to

the final part manufacturing in aerospace industry. Cost savings and model design/fabrication time

reductions greater than a factor of 4 have been realized for RP techniques as compared to current

standard model design/fabrication practices. Compared to its metal counterparts RP products are

short of strength and accuracy. But still they can be accepted in the preliminary stages of design

where full metal fabrication and machining processes consumes lot of money and time. Scaled

down model of the components and their final assembly with lesser accuracy are acceptable for

the initial design testing. The use of RP models will provide a rapid capability in the determination

of the aerodynamic characteristics of preliminary designs over a large Mach range. This range

covers the transonic regime, a regime in which analytical and empirical capabilities sometimes fall

short. However the industry with very high standard for safety and place for no deviations like the

aerospace sector cannot replace the proved machining processes or metal parts with the rapid

prototyping. Considerable research over the new kind of materials for fabrication and increasing

the capacity like size and strength of the current RP models can lead the aerospace sector into

greater heights.

8. Reference: 1. Advancement of rapid prototyping in aerospace industry -a review Vineet Kumar

vashistha, Rahul Makade, neeraj Mehla, Department of Mechanical Engineering,

NIT,Hmaripur, India.

2. Rapid Prototyping Industrial Analysis, Trevor Boehm, Maria-Isabel Carnasciali , M.

Elizabeth Douglas, Marco Gero Fernandez ,Christopher Williams

3. Rapid prototyping technologies, applications and part deposition planning Pulak M.

Pandey, Department of Mechanical Engineering, IIT,Delhi, India.

4. "Rapid Prototyping is Coming of Age," Steven Ashley, Mechanical Engineering, vol.

117, no. 7, July 1995, pp. 62-68.

5. Wikipedia.org

6. http://www.hk3dprinting.co.uk/aerospace-rapid-prototyping.html

7. http://www.proto3000.com