Under the guidance of Mr. Ankit Bajpai, Sohan Kumar submitted a report on rapid prototyping techniques. The report defines rapid prototyping as a group of manufacturing processes that create a 3D physical object directly from a 3D CAD model. It discusses the basic rapid prototyping process of converting CAD models to STL format and building the model layer-by-layer. Major rapid prototyping techniques covered include stereolithography, laminated object manufacturing, selective laser sintering, and fused deposition modeling. The report concludes with applications of rapid prototyping in engineering, medicine, arts, and rapid tooling.

1. UNDER GUIDANCE OF
1. MR ANKIT BAJPAI
Department of MECHANICAL Engg., DBIT, DEHRADUN
SUBMITTED BY
Sohan kumar
B. Tech(6 th sem)
Mechanical Engg.
(2012-16)
DEV BHOOMI INSTITUTE OF TECHNOLOGY
DEHRADUN , UTTRAKHAND- 248007

2.  .Introduction
 .Need for prototyping
 .Difference b/w Rapid prototyping and Traditional Fabrication
 Basics of Rapid prototyping(RP)
 .Rapid prototyping techniques
 Material Used in RP
 .Applications of RP

3. Introduction
 Rapid Prototyping Technology is a group
of manufacturing processes that enable
the direct physical realization of 3D
computer models.
 This technology converts the 3D
computer data provided by a dedicated
file format directly to a physical model,
layer by layer with a high degree of
accuracy.
 The presentation gives an overview on
existing major RP techniques and their
applications in engineering fields
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Fig 1: Flying sculpture called “the little shining man”
created using rapid prototyping technique.

4.  RPT and Rapid Manufacturing (RM)
offers great potential for producing
models and parts.
 By this reliability of product can be
increased, investment of time and money
is less risky.
 RPT can automatically construct
physical models CAD data.
 Rapid prototyping is an "additive"
process, combining layers of paper, wax,
or plastic to create a solid object.
 In contrast, most machining processes
are "subtractive" processes that remove
material from a solid block.
 Most prototypes require from one to
seventy-two hours.
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Fig 2: Rotors made using rapid prototyping techniques

5. 08-10-2013 5
Design & Manufacturing, NIT Silchar

6. 08-10-2013 6
Design & Manufacturing, NIT Silchar

7. The Basic Process
 Create a CAD model of the design
# Object to be built is modelled using CAD software.
# Solid modellers like ProE yield better results.
# Existing CAD file may also be used
 Convert the CAD model to STL (Standard Tessellation Language)
format
# STL format is the standard of rapid prototyping industry.
# This format represent 3D surface as an assembly of planar triangles and
describes only surface geometry. (without any representation of colour,
texture etc.)
 Slice the STL file into thin cross-sectional layers
# Several programmes are available for this.
# STL models are sliced into a number of layers (.01mm to .7mm).
# Orientation size and location are adjusted using the software.
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department of
mechanical,DBIT,DEHRADUN

8.  Construct the model one layer atop another
# RP machine builds one layer at a time from polymers, paper, or powdered
metal.
# Fairly autonomous needing little human intervention.
 Clean and finish the model
# Post processing step.
# Prototype may require minor cleaning and surface treatment.
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9. Rapid Prototyping Techniques
Most commercially available rapid prototyping machines use one
of the five techniques
 Stereolithography (SL or SLA)
 Laminated object manufacturing
 Selective Laser Sintering
 Fused deposition modeling
 Solid Ground Curing
 3D ink jet printing
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Fig 3: SL Machine

10. Stereolithography (SL or SLA)
 Builds 3D model from liquid photo sensitive polymers when exposed to UV rays.
 Model is built upon a platform situated just below the surface of liquid epoxy or
acrylate resin.
 A low power highly focused UV laser traces out the first layer, solidifying model
cross section.
 An elevator incrementally lowers the platform into the liquid polymer.
 Process is repeated until prototype is complete.
 Model is the placed in an UV oven for complete curing.
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Fig 4: Stereolithography

11. Laminated Object Manufacturing
 Layer of adhesive coated sheet materials are bonded to form a prototype.
 Paper laminated with heat activated glue is rolled up on spools.
 Heated roller applies pressure to bond the paper to the base.
 Feeder/collector mechanism advances paper.
 Laser cuts the outline of first layer.
 Platform is lowered and fresh material is advanced.
 Process is repeated and a roller bonds the layers.
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Fig 5: Laminated Object Manufacturing

12. Selective Laser Sintering
 Uses laser beam to selectively fuse powdered materials such as nylon,
elastomer or metal into a solid object.
 Parts are built on a platform which sits below the surface in a bin of heat
fusible powder.
 Laser traces the pattern of first layer, sintering it together.
 Then platform is lowered, powder is reapplied and process is repeated.
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Fig 6: Selective Laser Sintering

13. Fused Deposition Modelling
 Filaments of heated thermoplastics are extruded from a tip that moves in the
platform to form the first layer.
 The platform is maintained at a lower temperature, so that the thermoplastic
quickly hardens.
 After the platform lowers, the extrusion head deposits a second layer upon
the first.
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Fig 7: Fused Deposition Modelling

14. Solid Ground Curing (SGC)
 Similar to stereolithography in that both use ultraviolet light to selectively
harden photosensitive polymers. Unlike SLA, SGC cures an entire layer at a
time.
 First, photosensitive resin is sprayed on the build platform.
 The machine develops a photo mask (like a stencil) of the layer to be built. This
photo mask is printed on a glass plate above the build platform using an
electrostatic process.
 The mask is then exposed to UV light, which only passes through the
transparent portions of the mask to selectively harden the shape of the current
layer.
 After the layer is cured, the machine vacuums up the excess liquid resin.
 The top surface is milled flat, and then the process repeats to build the next
layer.
 When the part is complete, it must be de-waxed by immersing it in a solvent
bath.
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Fig 8: Solid Ground Curing
12/02/2015
Dbit,dehradun

16. 3-D Ink Jet Printing
 Parts are built upon a platform situated in a
bin full of powder material.
 An ink-jet printing head selectively
deposits or "prints" a binder fluid to fuse
the powder together in the desired areas.
 Unbound powder remains to support the
part.
 The platform is lowered, more powder
added and levelled, and the process
repeated.
 Finished parts can be infiltrated with wax,
glue, or other sealants to improve durability
and surface finish.
 Typical layer thicknesses are on the order of
0.1 mm.
 This process is very fast, and produces parts
with a slightly grainy surface.
 There are also other different types of 3D
printing available in the market which gives
very good accuracy.
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Fig 9: 3-D Ink Jet Printing

17.  Almost all materials can be manufactured
through rapid prototyping operation, but
polymer are the work piece most commonly
used today,because they are less expensive.
 .Poly carbonate
 .ABS
 .Metals
 .Ceramics
 and many mores
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18. Applications of Rapid Prototyping
Engineering
 Made use in space stations and space shuttles.
 Planning to install an RP machine in ISS for making spare parts.
 Functional parts in F1 racing cars and fighter jets like F-18.
Medical Applications
 Custom-fit, clear plastic aligners (braces) can be produced.
 Used in hearing aids to make custom fit shells.
Arts and Archaeology
 Selective Laser Sintering with marble powders can help to restore or duplicate
ancient statues.
Rapid Tooling
 Tools are made by CNC-machining, electro-discharge machining, or by hand.
 All are expensive and time consuming.
 Manufacturers would like to incorporate rapid prototyping techniques to speed the
process. 18

20. Conclusion
 Modern CNC machines have high removal rates which helps in fast
machining.
 For certain applications machining will continue to be a useful
manufacturing process.
 One should regard RPT as one more option in the toolkit for
manufacturing parts.
 Rapid prototyping will not make machining obsolete, but rather
complement it.
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References
 en.wikipedia.org/wiki/Rapid_prototyping
 www.protosystech.com/rapid-prototyping.h
 P.M. Pandey, N.V Reddy, S. G. Dhande, ‘Slicing
procedure in layer manufacturing’, Rapid prototyping
journal 9(5), 2003, page 274 to 288.

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