Rapid Prototyping (RP) 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.
OR
Rapid prototyping is the fabrication of parts from CAD data
sources.
There is a multitude of experimental RP methodologies either in
development or used by small groups of individuals. This section
will focus on RP techniques that are currently commercially
available, including Stereo lithography (SLA), Selective Laser
Sintering (SLS), Laminated Object Manufacturing (LOM), Fused
Deposition Modeling (FDM), Solid Ground Curing (SGC), and Ink Jet
printing techniques.
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The reasons of Rapid Prototyping are
 To increase effective communication.
 To decrease development time.
 To decrease costly mistakes.
 To minimize sustaining engineering changes.
 To extend product lifetime by adding necessary features and
eliminating redundant features early in the design.
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The basic methodology for all current rapid prototyping techniques
can be summarized as follows:
1.A CAD model is constructed, then converted to STL format. The
resolution can be set to minimize stair stepping.
2.The RP machine processes the .STL file by creating sliced layers of
the model.
3.The first layer of the physical model is created. The model is then
lowered by the thickness of the next layer, and the process is
repeated until completion of the model.
4.The model and any supports are removed. The surface of the
model is then finished and cleaned.
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• Stereo lithography
• 3-Dimensional Printing
• Fused Deposition Modeling
• Laminated Object Manufacturing
• Selective Laser Sintering
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A stereolithography machine uses a computer controlled laser to
cure a photo-sensitive resin, layer by layer, to create the 3D part.
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In this method roller is to distribute and compress the powder
evenly in the fabrication chamber. The multi-channel jetting
head then creates a layer of liquid adhesive in the geometry of
the part in the bed of powder. A layer of the part geometry is
created when the powder that containing liquid adhesive bonds
and hardens.
When a layer is completed, the fabrication piston will move down
in increments. These increments are specified to determine the
layer thickness. Additional layers are formed to create the entire
part geometry. Once the part is completed, the fabrication
piston is raised to expose the part. With the part exposed, the
access powder can be brushed away.
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In this process, a strand of filament is unwound
from the coil and fed into an extrusion nozzle. The
plastic is melted and controlled by the nozzle. The
nozzle is able to move in the X and Y directions and
is mounted to a stage system. Layers are formed
by very small beads of plastic being deposited from
the nozzle in the shape of the part geometry. The
plastic beads begin harden immediately after being
extruded from the nozzle in addition to bonding
with the layer beneath
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The LOM process produces prototypes by utilizing layer building
concepts. During the LOM process, a laser is used to cut
individual layers of paper to form a prototype.
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SLS process produces parts directly from 3D CAD model; layer by
layer similar to SLA but rather than liquid resin powder is used.
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 Rapid Prototyping can provide with concept proof that would be
required for attracting funds.
 The Prototype gives the user a fair idea about the final look of the
product.
 Rapid prototyping can enhance the early visibility.
 It is easier to find the design flaws in the early developmental stages.
 Active participation among the users and producer is encouraged by
rapid prototyping.
 As the development costs are reduced, Rapid prototyping proves to
be cost effective.
 The user can get a higher output.
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 Some people are of the opinion that rapid prototyping is not
effective because, in actual, it fails in replication of the real
product or system.
 disadvantage of rapid prototyping is that it may not be suitable
for large sized applications.
 The user may have very high expectations about the prototype’s
performance and the designer is unable to deliver these.
 The system could be left unfinished due to various reasons or
the system may be implemented before it is completely ready.
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 Design
 CAD model Verification
 Visualizing object
 Proof of concept
 Engineering, Analysis and planning
 Form and fit models
 Flow analysis
 Stress distribution
 Mock-up
 Diagnostic and surgical operation planning
 Design and fabrication of custom prosthesis and
 implant
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