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THE TECHNICAL PAPER PRESENTATION ON Rapid prototyping Submitted by


Under the guidance of




Presentation at :

Govt. College of Engg., Jalgaon. 2000-2001

Rapid Prototyping

ACKNOWLEDGEMENTIt 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. KSHIRSAGARIII Year B.E. Prod. College of Engg. & Tech. ,Akola


Rapid Prototyping


ParticularIntroduction 1 What is Prototyping Rapid prototyping differs by

Page No.

2. 3. 4. 5. 6.

The principle Advantages Need for Prototype Development Case Study for Rapid Prototyping Basic Process Stereolithography LOM 3D Plotting

2 2 3 3 8

7. 8. 9.

Materials for Rapid Prototyping Conclusion Bibliography

12 13 14


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


Rapid Prototypingthe 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 PrototypeIt 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


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.)

DevelopmentThe 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 PrototypingThe 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.


Rapid PrototypingRapid 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


Rapid PrototypingConsumer 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 Logitechs team returned with a functional SLA prototype. The customers 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 SoonerThe 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 products 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


Rapid Prototypingbetter are its prospects for obtaining and retaining a large share of the market For each month cut from a products 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 QualityThe 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 RangeTodays 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.


Rapid PrototypingClearly, 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 FailureIt 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.


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)


Rapid Prototyping

TypesThere 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.


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.


Rapid PrototypingUsed 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.


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.


Rapid Prototyping

ConclusionTodays 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.


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.


Rapid Prototyping

x Head nozzle y


Plat form

Process Chamber


Fused deposition


Rapid Prototyping

Scanner Laser

Laser sinking

Elevation Support Surface of resin Platform Vat Resin



Rapid Prototyping

Cross hatching by laser

Laminated Object Manufacturing (LOM)