17 - rapid prototype

7/28/2019 17 - Rapid Prototype

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Ken Youssefi MAE dept, SJSU 1

(RP)


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The design teams should use two methods for

modeling and simulating a products performance.

Physical models (prototype)

Analytical (virtual, digital) models


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Analytical (Digital) models

Computer generated models (3D solid model) are used to

perform finite element analysis (stress, deflection, thermal, ),

drop test, flow analysis, kinematics (motion) analysis andoptimization.

Stress and

deflection

analysis

Thermal analysis


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Analytical (virtual) models

Flow analysisDrop test

Motion andForce analysis


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Analytical (digital) models

Analytical models cannot be expected to produce accurate

results if the underlying physics is not well understood.

A detailed model may require a long development time.

Unexpected phenomena and effects are most likely to be

discovered during the physical prototype testing

Advantages

The analytical model, due to theoretical limitation, may poorly

estimate the actual product behavior.

Disadvantages

Analytical models are more flexible than physical models. It

is much easier to change parameters and to study differentdesign scenarios.

Less expensive than a physical model.


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Physical models

There are two main considerations in the development of a

physical model; Cost and Cycle Time

It is not practical to build a prototype at every level of the

product development stages.

Due to competition, a new product has to enter the

market at a fast pace.

Improvement in solid modeling tools and design philosophy

(concurrent engineering) has reduced considerably the

number of physical prototypes needed to verify designparameters and configurations.

Analytical (digital) model should be used to study the range of

feasible parameters and then the physical model is used to

verify and fine tune the design.


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Physical PrototypeA physical prototype is build for the following reasons:

Verifying and Learning

Does the product work?

Does the product meet the design team

specification and requirements?

Does the product meet the customer needs?

Integration

Prototypes are used to ensure that different

subsystems interface correctly.

Communication

A physical prototype makes it easier for the

management, customers and vendors to visualize

the design and understand its function.


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Prototyping Processes

Through out the years, many different production

processes have been used to create prototypes (cast

metal molds, epoxy molds, silicon rubber molds, injection

molding, CNC machining ..). But in recent years, due tosophisticated computer software (3D parametric

modelers), Material Addition Rapid Prototyping hasemerged as the preferred process for many application.

Material Removal

Casting/Molding

Material Addition

Three major categories


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Rapid Prototyping (Direct Digital Manufacturing)


The popular commercial rapid prototyping processes can

be categorized as: Stereolithography (laser fusion), Fused-Deposition Modeling (FDM), Inkjet printing and Lamination.

Solid freeform fabrication involves constructing a three

dimensional object one cross sectional layer at a time,

depositing a material or by solidifying liquid or hardening

powder. The object is first created using a 3D parametric

modeler (Pro/E, Unigraphics, SolidWorks, ).

RapidPrototyping


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RP Starting Materials


Liquid polymers that are cured layer bylayer into solid polymers (plastics)

Powder that is bonded layer by layer intoa solid

Solid sheets that are laminated to form the

solid part

Solid polymer that is heated (melted) and

deposited layer by layer to form the solid


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Stereolithography (Liquid-Based)

Stereolithography (STL or SLA) was the first RP technology

dating back 25 years.

The process uses photosensitive liquid

polymer as the material.

A laser beam is used to cure (harden) theliquid. The beam hits the liquid according to

the path program generated by the CAD

The laser beam solidifies one layer at a timewhile the platform is lowered by the thickness

of each layer.


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The Stereolithography Process

You create a 3-D model of your object in a CAD program

and save it as an .stl file

A special software chops the CAD model up into thin

layers typically 5 to 10 layers/millimeter.

The 3-D printer's laser "paints" one of the layers,

exposing the liquid plastic in the tank and hardening it.

The platform drops down into the tank a fraction of a

millimeter and the laser paints the next layer.

This process repeats, layer by layer, until the model iscomplete. This is not a particularly quick process.

Depending on the part size and number of layers, a typical

run might take six to 12 hours. Runs over several days are

possible for large objects.


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Rapid Prototyping3D solid model of the object The part is divided into slices

Only 10% of the

slices are shown

Part is made onelayer at a time


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Prototyping ProcessesStereolithography

The process is based on hardening a liquid photopolymer into a

specific shape. Smallest tolerance that can be achieved is .0005


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The ultraviolet "oven"

used to cure completed

objects.

The platform at the end of a

print run, shown here with

several identical objects.

The platform in

the tank of

photopolymer at

the beginning of

a print run.

SLA

Video
http://www.youtube.com/watch?v=nwQ5HA8sE-khttp://www.youtube.com/watch?v=nwQ5HA8sE-k


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Ken Youssefi MAE dept, SJSU 16The wrench


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Prototyping Processes

Fused-Deposition Modeling (FDM) starting material is solid

polymer

A thermoplastic filament

is extruded through a

small orifice of a heated

die. Layer thickness is

between .01 to .02 inch,

best achievable

tolerance in vertical

direction, tolerance of

.001 inch is attainable inxy plane.


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FDM

Ken Youssefi MAE dept, SJSU 18The jet plane


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mechanism



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uPrint machine



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Affordable 3D printer (ABS)



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Prototyping Processes - ZPrint

Binder

Powder

storage

Roller spreads

a layer of

powder material

Feed Build

Standard inkjetprinthead

Piston lowersmaking room for

new layer

Color

printer


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Inkjet Printing (powder 650 model)



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Working wrench



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ZPrint - examples

Concept Modeling

Size: 21 x 33 x 20 cm

Printing Time: 12 hours

Consumer Products

Size: 8 x 18 x 5 cmPrinting Time: 2 hours

Medical

Size: 25 x 20 x 10 cm

Printing Time: 5.5 hours

Footwear

Size: 10 x 30 x 5 cm


AutomotiveSize: 25 x 28 x 11 cm



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http://money.cnn.com/video/technology/201

1/01/21/t_tt_3d_food_printer.cnnmoney/

3D dessert printer

http://ccinsider.comedycentral.com/2011/08/04

/3d-printer-creates-stephen-colbert-bust/

3D model of Steven Colbert

http://www.pcworld.com/article/229927/makerbot_3d_prints_

stephen_colberts_head_stephen_has_wings_and_tentacles

who_knew.html
http://money.cnn.com/video/technology/2011/01/21/t_tt_3d_food_printer.cnnmoney/http://money.cnn.com/video/technology/2011/01/21/t_tt_3d_food_printer.cnnmoney/http://ccinsider.comedycentral.com/2011/08/04/3d-printer-creates-stephen-colbert-bust/http://ccinsider.comedycentral.com/2011/08/04/3d-printer-creates-stephen-colbert-bust/http://www.pcworld.com/article/229927/makerbot_3d_prints_stephen_colberts_head_stephen_has_wings_and_tentacleswho_knew.htmlhttp://www.pcworld.com/article/229927/makerbot_3d_prints_stephen_colberts_head_stephen_has_wings_and_tentacleswho_knew.htmlhttp://www.pcworld.com/article/229927/makerbot_3d_prints_stephen_colberts_head_stephen_has_wings_and_tentacleswho_knew.htmlhttp://www.pcworld.com/article/229927/makerbot_3d_prints_stephen_colberts_head_stephen_has_wings_and_tentacleswho_knew.htmlhttp://www.pcworld.com/article/229927/makerbot_3d_prints_stephen_colberts_head_stephen_has_wings_and_tentacleswho_knew.htmlhttp://www.pcworld.com/article/229927/makerbot_3d_prints_stephen_colberts_head_stephen_has_wings_and_tentacleswho_knew.htmlhttp://ccinsider.comedycentral.com/2011/08/04/3d-printer-creates-stephen-colbert-bust/http://ccinsider.comedycentral.com/2011/08/04/3d-printer-creates-stephen-colbert-bust/http://ccinsider.comedycentral.com/2011/08/04/3d-printer-creates-stephen-colbert-bust/http://ccinsider.comedycentral.com/2011/08/04/3d-printer-creates-stephen-colbert-bust/http://ccinsider.comedycentral.com/2011/08/04/3d-printer-creates-stephen-colbert-bust/http://ccinsider.comedycentral.com/2011/08/04/3d-printer-creates-stephen-colbert-bust/http://ccinsider.comedycentral.com/2011/08/04/3d-printer-creates-stephen-colbert-bust/http://ccinsider.comedycentral.com/2011/08/04/3d-printer-creates-stephen-colbert-bust/http://ccinsider.comedycentral.com/2011/08/04/3d-printer-creates-stephen-colbert-bust/http://ccinsider.comedycentral.com/2011/08/04/3d-printer-creates-stephen-colbert-bust/http://ccinsider.comedycentral.com/2011/08/04/3d-printer-creates-stephen-colbert-bust/http://ccinsider.comedycentral.com/2011/08/04/3d-printer-creates-stephen-colbert-bust/http://money.cnn.com/video/technology/2011/01/21/t_tt_3d_food_printer.cnnmoney/http://money.cnn.com/video/technology/2011/01/21/t_tt_3d_food_printer.cnnmoney/


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3D Metal Printing



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Bioprinting Organs The Future


17 - rapid prototype

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