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THE TECHNICAL PAPER PRESENTATION
ON
“ Rapid prototyping ”
Submitted byMr. VILAS P. KSHIRSAGAR
Mr. TUSHAR V. KULKARNI Mr. SUNIL U. DHAKANE
Mr. SANTOSH D. SOLANKE Mr. SANJAY P. HINGANKAR
Under the guidance ofPROF. C.V. DESHMUKH
( H.O.D.)
PROF. S.K. PATIL PROF. D.V. SHIRBHATE
Presentation at :Govt. College of Engg., Jalgaon.
2000-2001
Rapid Prototyping
ACKNOWLEDGEMENT
It gives me great pleasure on bringing out the seminar entitled,
“RAPID PROTOTYPING ”
I wish to express my heart bound thanks to my guide Prof. C.V. Deshmukh (H.O.D.), Prof. D.V. Shirbhate & Prof. S.K. Patil for their guidance, encouragement and allowing to succeeding the project.
Last, not the least...., my cordial thanks to all those friends and well wishers, who contributed their bit in the successful completion of my task.
Mr. VILAS P. KSHIRSAGAR
III Year B.E. Prod. College of Engg. & Tech. ,Akola
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Rapid Prototyping
INDEX
Sr.No. Particular Page No.
1. Introduction 1
What is Prototyping
Rapid prototyping differs by
2. The principle Advantages 2
3. Need for Prototype 2
4. Development 3
5. Case Study for Rapid Prototyping 3
6. Basic Process 8
Stereolithography
LOM
3D Plotting
7. Materials for Rapid Prototyping 12
8. Conclusion 13
9. Bibliography 14
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Rapid Prototyping
An Introduction to Rapid PrototypingThe ability to rapidly produce accurate, tangible models of
products designed on a computer aided design system.
Rapid prototyping is a technology of producing a, 3
dimensional visual prototype or model direct from a CAD file. Rapid
prototyping is based on CAD computer aided design.
What is Rapid Prototyping?
The term "rapid prototyping" is a relatively new expression
for the generation of three-dimensional models manufactured without the need
for machining or tooling.
Production of models by machining has a number of limitations:-
1. Material removed during forming is difficult to reclaim.
2. Machining, in the form of drilling, turning, milling, spark erosion etc., is
limited by the shapes it can produce.
3. In the event of design change conventional tooling such as patterns, core
boxes, dies, jigs etc., become expensive to alter and, in many cases, may
require complete re-manufacture.
Rapid prototyping differs by:-
Adding material layer by layer until the desired shape is
achieved, immediately reducing or avoiding the loss of material. Cutting out
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Rapid Prototyping
the conventional draftsperson, patternmaker and in some situations even the
moulder, the system goes a long way towards reducing time taken and cost
and improving accuracy.
The principle advantages of using this technology are: -
1. Speed at which the solid model is generated.
2. The complexity of the model does not form any limitations to its production.
3. The early use of these models was to assist the designer in determining fit
and form. It also provided the sales team with a 3 dimensional object to
show to a prospective customer, this being far better than the traditional
orthographic drawing which many people find difficult to interpret.
4. Concept modeling
5. Aesthetic
6. To make an impossible object.
The Need for a Prototype
It is very difficult, and in many instances impossible, to
produce an article that will serve the purpose of use without making
modifications to the original shape or general design. There are many
examples of design failure that have been the cause of serious injury and
costly litigation.
Rapid Prototyping concentrates the mind on getting the product
Right First Time
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Rapid Prototyping
Other uses for RP models are:-
Discussion piece.
Design and fit.
Assembly capabilities.
Suitability of mechanical properties.
Manufacturing process capabilities (forging,
casting, pressing, fabrication etc.)
Development
The first rapid prototyping system was developed on to the
US model in 1988 and gave the Engg. the opportunity to produce 3
dimensional object from computer aided design (CAD) data.
The development of this technology has reach into many of traditional fields.
The Case for Rapid Prototyping
The prime concern of any management is to maintain and,
where possible, improve profitability. We are all aware that profits accrue when
income from sales exceed total cost and that profits can be increased by
improved sales or reduction in costs, or both.
Many technologies have been developed which have been
successful in reducing the labour content, which, in most cases is the major
cost.
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Rapid Prototyping
Rapid prototyping is only some ten years old and is
already proving to be a very cost-effective way of producing models/patterns.
There are over 500 SLA machines installed world wide (approximately 20 in
the UK) to famous companies such as :-
Ford, General Motors, Rover, Rolls Royce, IBM, Boeing, BAe.
These companies have recognised the power of this
technology to boost their profits and competitiveness. Whilst most companies
are, understandably, reluctant to reveal the extent to which the technology
contributes to their profitability, BAe. claims that one of its systems paid for
itself within 5 months. Rover, who bought the largest system available, is
already considering the purchase of other system.
Of the 500 systems sold world-wide, about 15% are being
used by RP bureaux, operating on a sub-contract basis. In the UK this number
is significantly higher at 50%.
All the companies are exploiting the power of RP to increase their profits as
discussed below.
Increasing Sales by:-
* Producing visual models for market research, publicity, packaging etc.,
* Getting to market sooner.
* Generating customer goodwill through improved quality.
* Expanding the product range.
* Reducing the cost and fear of failure.
* Visual Models
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Rapid Prototyping
Consumer product manufacturers find value in having
tangible models of their proposed products to show to customers.
IBM used SLA to produce operating display units of its
ThinkPad tablet computer for the annual COMDEX show.
Key Tronics, who manufacture computer keyboards, create
physical parts for customer approval.
Logitech, the worlds largest manufacturer of pointing
devices, was asked, by a "blue chip computer company" to quote on a unique
two-button mouse; in less than two weeks from the initial request Logitech’s
team returned with a functional SLA prototype. The customer’s reaction was
one of ‘disbelief '. Part quality was so superior that the computer giant
awarded the contract on the spot. It is thought that this single order paid for
the SLA system.
Coca-Cola used RP to design the nostalgic (coke bottle) curves into a
contemporary 20 ounce plastic Coke bottle.
Getting to Market Sooner
The phrase "Time to Market" is first thought to have been
used in a classic 1983 article by McKinsey & Co on product development that
stated:
"Six months of delay can reduce a product’s life cycle profits by 33%".
The author of that article has since written: "The first product to market has a
100% share of that market in the beginning. The earlier a product appears, the
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Rapid Prototyping
better are its prospects for obtaining and retaining a large share of the
market… For each month cut from a product’s development cycle a month can
be added to its sales life, representing an extra month of revenue and profit…
It gains more customer loyalty due to the cost of switching to another
product… A third benefit is higher profit margins. If a new product appears
before there is competition, the company will enjoy more pricing freedom,
making higher profit margins…"
DePuy, the surgical implant manufacturers, state: The
major goals are decreasing the time to develop a product, while allowing
manufacturing to launch the product quickly, resulting in a larger return on
investment… The return from launching a single product several months early
pays for the entire technology investment."
Generating Customer Goodwill through Improved Quality
The end result has been less re-design, improved products
and most importantly, greater customer satisfaction. This has lead to many
companies in the USA producing a RP model with every quote.
Expanding Product Range
Today’s market place is characterised by more frequent
introductions of more product variants each having a life cycle than the
previous one. In addition, lead-times demanded are shorter than ever before.
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Rapid Prototyping
Clearly, RP makes a positive contribution here, by compressing development
times, thus making it possible to respond to the demands of the niche markets
and to introduce new products more frequently.
Reducing the Cost and Fear of Failure
It takes a very confident person to allocate / sanction large
amounts of money and resources on tooling for a product that might not make
it on the market. This will inevitably make people cautious and restrict their
design flair to those tried and tested shapes and systems. Where a relatively
cheap model can be produced quickly it reduces the fear that traditional
methods attract allowing the designer to be more adventurous.
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Rapid Prototyping
Rapid Prototyping, the basic processRP machines process CAD data by slicing the computer
model into layers, each layer being typically 0.1 - 0.25mm thick. The machine
then uses this data to construct the model layer by layer, each layer being
bonded to the previous until a solid object is formed. Due to this laminated
method of construction a stepped surface is developed on curved faces, the
removal of which is essential if maximum advantage of the process is to be
realised
The models are built in a build envelope or tank, and so do
not have mould cavity walls or patterns to rest on during construction. As a
result a support structure is also built along with the model itself. Once the
model is complete, and the remaining powder or liquid in the build tank is
expunged, and the support structure must be removed. This is similar to the
removal of risers and channels in traditional casting processes. Most models
can then be subjected to post production methods (e.g. sanding).
The lamination and the support structure is designed by
the software used to drive the process. This translates a conventional 3D CAD
drawing into the STL format used by the Rapid Prototyping machines (see
Software)
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Rapid Prototyping
Types
There are three major types of Rapid Prototyping. They are
1. Photopolymer (Stereolithography),
2. Laminated object modeling,
3. 3D Plotting.
As Rapid Prototyping technology develops, the number of methods which can
be used to produce prototypes increase, these are some of them.
1. Rapid Prototyping - Fused Deposition Manufacture
(FDM)
Materials used include:-
ABS
Medical ABS
Investment casting wax
Elastomers similar to low and high density
Polyethylene
Polypropylene.
A thermo-polymer is extruded from a travelling head
having a single, fine nozzle. The head travels in the X axis while the table or
platform travels in the Y axis and descends at predetermined increments in the
Z axis. On leaving the nozzle the thermo- polymer adheres and hardens to the
previous layer.
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Rapid Prototyping
2. Rapid Prototyping - Laminated Object Manufacturing
(LOM)
LOM was developed by Michael Feygin of Helysis.
As the name implies the process laminates thin sheets of
film (paper or plastic), the laser has only to cut/scan the periphery of each
layer and not the whole surface as in SLA.
The build material (paper with a thermo-setting resin glue
on its under side) is stretched from a supply roller across an anvil or platform
to a take- up roller on the other side. A heated roller passes over the paper
bonding it to the platform or previous layer. A laser, focused to penetrate
through one thickness of paper cuts the profile of that layer. The excess paper
around and inside the model is etched into small squares to facilitate its
removal. Meanwhile, this surplus material provides support for the developing
model during the build process. The process of gluing and cutting continuous
layer by layer until the model is complete.
To reduce the build time, double or even triple layers are
cut at one time which increases the size of the steps on curved surfaces and
the post processing necessary to smooth those surfaces.
Applications of LOM objects:
LOM objects are durable, multilayered structures which can be machined,
sanded, polished, coated and painted.
Used as precise patterns for secondary tooling processes such as rubber
moulding, sand casting and direct investment casting.
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Rapid Prototyping
Used for limited testing.
Used as visual models.
NASA have used the LOM to produce 12 ‘Hot’ gas manifold for the shuttle
main engine.
3. SLA Process. ( Stereolithography )
SLA system builds shapes using light to selectively solidify liquid photocurable
resins.
Principle :
Laser SLA crates acrylic or epoxy parts directly from a vat
of liquid photocurable polymer by selectively solidifying the polymer with a
scanning laser beam.
Building -up Technique
1. Building - up parts on an elevator platform.
2. The platform is lowered into the vat by the distance of the layer thickness.
3. Guiding a laser beam using servo-controlled galvanometer mirror and
drawing a cross -sectional layer in the x-y plane to form a solid section.
4. The platform is then lowered into the vat and the next layer is drawn and
adhered to the previous layer.
5. These steps are repeated, layer-by-layer until the complete part is built up.
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Rapid Prototyping
Materials for R.P.There is a clear need to improve the mechanical properties
of the stereolithography resins and plastics currently being used.
Wax -like material that can be used for investment casting of metal parts.
Polystyrene for selective laser sintering.
Polyamide (nylon) is generally used for parts requiring higher strength and/ or
toughness.
ABS that is, with ductility to test snap fit, flexible hinges and other functional
properties of a design.
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Rapid Prototyping
ConclusionToday’s market is customer market. R & D is the heart of any progressing,
developing industry because R&D can only word of new blood in industry, so
that no obsolance stage will covered in the life of industry.
R & D Engg. developing new shapes, size, design, type of various component
for the establishing machine or product but hurdle is to produce the part
according to design immediately for getting immediate solution to the problem
which they want to rid off.
Now the time has come where, the design egg. Just can imagine the new
design, reproduce on the paper and within the few minute the product will be
ready with this technology ( prototyping) because the time has come where
this technology is capable to give the product manufactured within few minutes
if product details are fed to computer as data.
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Rapid Prototyping
Bibliography1. “ R.P. Systems” Mech. Engg., April. 1991, PP 34-43
2. Jacobs. Paul F. “ R.P. & Manufacturing” , Society of manufacturing Engg.,
Dearborn 1992.
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Rapid Prototyping
x
y
Z
17
Plat form
Process Chamber
Fig. Fused deposition
Head nozzle
Rapid Prototyping
18
Laser
Scanner Laser sinking
Elevation
Surface of resin
Platform
ResinVat
Support
Stereolithography
Rapid Prototyping
19
Laminated Object Manufacturing (LOM)
Cross hatching by laser
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