common processes in RP. like SLA,SLS,3DP,LOM,FDM and the uses and common steps in the rapid prototyping process.

1. RAPID PROTOTYPING
Outline:
 Definition
 Layered Manufacturing Concept
 Basic Methodology for all RP Techniques
 Sterio Lithography
 Selective Laser Sintering
 3-d Printing
 Solider Process
 Fused deposition Modelling
 Laminated Object Manufacturing
 Uses of Rapid Prototyping
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2. DEFINITION
Physical model that directly represents the component
is much better than pure computer visualization.
Rapid prototyping is a means through which the
product geometry as modeled in the earlier stages is
directly utilized to get the physical shape of the
component.
 RP refers to a variety of specialized equipment,
software and material capable by using 3D CAD design
data input to directly fabricate geometrically complex
objects.
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3. LAYERED MANUFACTURING CONCEPT
 In this method , a 3D model of the object in CAD is
first decomposed into cross –sectional layer
representations of very small thickness . The system
then generates trajectories for the material to be
added in each layer by the RP machine. The sacrificial
supporting layers are also simultaneously generated to
keep the unconnected layers in proper position.
 There are number of ways the data can be
represented. STL (STANDARD TRIANGULAR
LANGUAGE) is most common . Each physical layer
from above is then deposited and fused to the previous
layer using one of the many available deposition and
fusion technologies.
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4. Basic methodology for all RP techniques
A CAD model is constructed and then converted to STL
(STANDARD TRIANGULAR LANGUAGE) format.
The RP device processes the STL file by creating sliced layers of
the model. The resolution of future model directly depends on
quantity of the layers or, since all layers must have identical
thickness, on the layer’s thickness.
The first layer of the physical model is created , the model is
then lowered by the one layer thickness, and the process is
repeated until completion of the model.
The model and any supports are removed ; the surface of the
model is then finished and cleaned . Machining also can be
considered as rapid prototyping, though it requires custom
fixturing and has inherent geometric limitation. 4

5. Steps in Rapid Prototyping
CAD SOFTWARE
RP SOFTWARE
RP MACHINE
Tightly
Integrated
system
Designer
Sliced data
STL file
Parts/ Tools/ Assemblies
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6. Principle Of Rapid Prototyping
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7. Technologies : Stereo lithography
 The most commonly used process for RP is the stereo
lithography or photo lithography. These systems build
shapes using light to selectively solidify photo curable
resins.
 Also convert 3- dimensional CAD data of physical
objects into vertical stacks of slices. A low-power
ultraviolet laser beam is then carefully traced across a
vat of photo curable liquid polymer ,producing a single
layer of solidified resin- the first slice of the object
under construction.
 The laser beam is guided across the surface (by servo
controlled galvanometer mirrors), drawing a cross-
sectional pattern in the x-y plane to form a solid
section. The initial layer is then lowered incrementally
by the height of the next slice ,whereupon the layer is
recoated with resin and another is traced on top of it
.this procedure is repeated until entire part is
fabricated.
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8. Schematic of Stereo lithography Device
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9. Disadvantages
 It is very expensive.
 It is limited to the photo-curable plastics material
only.
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10. Sample Parts 10

11. SELECTIVE LASER SINTERING
 In this a modulated laser beam follows the shape of a
slice of a CAD –generated object ;it traces the object
across a bin of special heat-fusible powders, heating
the particles so they fuse or sinter together.
 In SLS a layer of powdered material is spread out and
leveled in the plane .
 A CO2 laser then selectively traces the layer to fuse
those areas defined by the geometry of the cross-
section along with fusing to the bottom layer.
 The powders can be joined by melting or surface
bonding. The unfused material remains in place as the
support structure. After the initial layer is formed
,powder is reapplied, and the laser processes the next
layer.
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12. Schematic of Selective Laser Sintering Device
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13. Applications
 Because of the use of the metal powders, this process
is greatly used in application such as direct tooling
applications for investment and die casting
applications.
 Some of the materials used are plastics, waxes and
low- melting- temperature metal alloys.
MATERIAL USED
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14. 3-D PRINTING
 It can be compared to SLS, the difference is that
instead of laser beam ,liquid binder is applied to bond
the powder particles. A 3D Printer is operated in the
following sequence. The printer spreads a layer of
powder from the feed box to cover the surface onto the
loose powder, forming the first cross-section of the
part. Where the binder is printed , the powder’s
particles are glued together. The remaining powder is
loose and supports the part as it is being printed.
 When the cross- section is complete , the build
platform is lowered slightly, and a new layer of
powder is spread over its surface. The process is
repeated until the whole model is completed. The
build platform is raised and the loose powder is
vacuumed away, revealing the completed part.
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15. Schematic drawing
Schematic of 3-D Printing Device 15

16. 3-D Printing Process
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17. SOLIDER PROCESS
 Solider RP machines are large , tool –like units that
make models using light –curable photopolymers and
a photo masking technique analogous to that used to
manufacture printed circuit boards.
 Instead of a laser solidifying a photopolymer into
slices , an ultraviolet lamp hardens the material en
masse.
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18. FUSED DEPOSITION MODELLING
 In this process a plastic filament is unwounded from a
coil and supplies material to an extrusion nozzle.
 The nozzle is heated to melt the plastic and has a
mechanism, which can be moved in both horizontal
and vertical directions.
 As the nozzle is moved over the table in required
geometry, it deposits a thin bead of extruded plastic
to form each layer.
 The plastic hardens immediately after being squirted
from the nozzle and bonds to the layer below.
 Several materials are available for the process
including investments – casting wax.
 Some FDM systems utilize two extrusion nozzles: one
for deposition of a build material, and second for
deposition of washable material to make support
environment.
 Several FDM materials are in the engineering –
development stage, including polycarbonate,
polypropylene, PMMA (polymethyl methacrylate ),
and various polyesters.
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19. Schematic drawing
Schematic of Fused Deposition Modelling Machine 19

20. Sample FDM Parts
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21. LAMINATED OBJECT MANUFACTURING
 Laminated Object Manufacturing (LOM) machine works by
actually cutting the “slices” of the object out of a sheet of
paper foil and then bonding them together.
 The foil comes off the material supply roll and the laser
then cuts around the outline of the layer, it also hatches
the foil around the edge so that this can be easily broken
away when all of the layers have been bonded together.
 After the laser has cut out the top layer, a heated roller
moves over the top of foil to bond the layer to the rest of the
object.
 A sensor is used to measure the thickness of the foil as this
can vary and the machine will automatically adjust the
dimensions of the layer being cut to account for any
variation .
 The result is a part that like laminated wood.
 The further development of the concept of layering
manufacturing has resulted in creation of systems utilizing
metal sheets as a building material. 21

22. Schematic drawing
Schematic of Laminated Object Manufacturing Device
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23. USES OF RAPID PROTOTYPING
 Check the feasibility of new design concepts.
 Conduct market tests/evaluation.
 Asses the fit of complex mechanisms.
 Make many exact copies simultaneously.
 Make moulds for wax cores in castings.
 Use as a master for silicon and epoxy moulds.
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