Rapid Prototyping VACUUM CASTING1_2

7/29/2019 Rapid Prototyping VACUUM CASTING1_2

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RAPID PROTOTYPING

Anoop M Kuriyan

Roll no: 05S-7 Mechanical


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What is Rapid Prototyping ?

The termRapid prototyping(RP) refers to a class oftechnologies that can automatically construct

physical models from Computer-Aided Design

(CAD) data.

It is a free form fabrication technique by which a

total object of prescribed shape, dimension and

finish can be directly generated from the CAD based

geometrical model stored in a computer,with littlehuman intervention.


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The Basic Process

Although several rapid prototyping techniques

exist, all employ the same basic five-step

process. The steps are:1. Create a CAD model of the design

2. Convert the CAD model to STL format

3. Slice the STL file into thin cross-sectional layers4. Construct the model one layer atop another

5. Clean and finish the model


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Rapid prototyping Techniques

Most commercially available rapid prototypingmachines use one of seven techniques

Stereolithography

Laminated Object Manufacturing

Selective Laser Sintering

Fused Deposition Modeling

Solid Ground Curing 3-D Ink-Jet Printing


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Stereolithography

Patented in 1986

The model built on a platform

A low-power highly focused

UV laser traces the first layer.

An elevator incrementally

lowers the platform into the

liquid polymer

Sweeper re-coats the solidifiedlayer with liquid.

This process is repeated until

the prototype is complete.


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Laminated object manufacturing

Developed by Helisys of

Torrance, CA,

Layers of adhesive-coated sheet

material bonded together to

form a prototype.

Feeder/collector mechanismadvances the sheet over the

build platform .

Heated roller applies pressure to

bond the paper. Focused laser cuts the outline of

the first layer into the paper and

then cross-hatches the excess

area.


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Selective Laser sintering

Developed by Carl Deckard and

was patented in 1989. Uses a laser beam to

selectively fuse powderedmaterials, into a solid object.

Parts built upon a platform. A laser traces the pattern of

the first layer, sintering ittogether.

Platform lowered by theheight of the next layer and

powder is reapplied.

Process continues until part is

complete.


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Fusion Deposition Modeling Filaments of heated

thermoplastic extrudedfrom tip.

Controlled extrusion head

deposits very thin beads of

material . Platform maintained at

lower temperature and the

thermoplastic hardens .

The platform lowers, theextrusion head deposits a

second layer upon the first .


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Solid Ground Curing

Developed by Cubital, America

Inc. of Troy Michigan .

The Basic Steps : -

Spray The resin on the build

platform.

Develop photomask of the layer

built.

Expose the mask to UV light.

Vacuums up the excess resin.

Spray Wax in its place.

Top surface milled flat.


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3-D Ink-Jet Printing

Developed by MIT and

licensed to Soilgen. Parts are build upon

platform .

Ink jet printing head

deposits binder to fusepowder together .

Unbound powder supportspart .

Platform lowered,powderadded,leveled and processrepeated .

Finished parts infiltratedwith Wax or sealants.


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Applications of Rapid Prototyping

1. Engineering


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2. Architecture

Opera house in Sydney


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3.Medical Applications

Hearing aid


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4. Arts and ArcheologyDuplicating the statue


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5. Rapid Tooling

Tooling is one of the slowest and most expensive steps in

the manufacturing process, because of the extremely high

quality required. Tools often have complex geometries, yet

must be dimensionally accurate to within a hundredth of a

millimeter. In addition, tools must be hard, wear-resistant,

and have very low surface roughness (about 0.5

micrometers root mean square). To meet these

requirements, manufacturers would like to incorporate

rapid prototyping techniques .


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RPTvs. conventional technologies


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Advantages of Rapid Prototyping

Strength, Elasticity and Temperature Resistance.

Typical quantities

Standard accuracy

Time Savings

Surface structure

Cost

Use any type of model


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Future developments

.

increased speed

improved accuracy and surface finish

Wider range of materials increased size capacity

Distance Manufacturing on Demand


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Conclusion

Finally, the rise of rapid prototyping has spurred progressin traditional subtractive methods as well. Advances in

computerized path planning, numeric control, and

machine dynamics are increasing the speed and accuracy

of machining. Modern CNC machining centers can havespindle speeds of up to 100,000 RPM, with

correspondingly fast feed rates. 34 Such high material

removal rates translate into short build times. For certain

applications, particularly metals, machining will continue

to be a useful manufacturing process. Rapid prototyping

will not make machining obsolete, but rather complement

it.


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THANK YOU

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Rapid Prototyping VACUUM CASTING1_2