Rapid prototyping

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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