Prototyping an introduction The need. The basic methods. Low tech vs. high tech vs. virtual.

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Prototypingan introductionThe need.The basic
methods.Low tech vs. high tech vs. virtual.

• Dr. Lou Reifschneider
• TEC 316

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Development Time vs. Development Costsfor
Product Lifetime of 5 Years
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Trends in Product Design Cycle
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Prototyping ExampleApple PowerBook Duo Trackball
Product Design and DevelopmentChapter 12 Karl T.
Ulrich and Steven D. Eppinger2nd Edition, Irwin
McGraw-Hill, 2000
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Types of Prototypes
Physical
beta prototype
alpha prototype
ball support prototype
final product
trackball mechanism linked to circuit simulation
Comprehensive
Focused
Product Design and DevelopmentChapter 12 Karl T.
Ulrich and Steven D. Eppinger2nd Edition, Irwin
McGraw-Hill, 2000
simulation of trackball circuits
not generally feasible
equations modeling ball supports
Analytical
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Four Uses of Prototypes

• Learning
• answering questions about performance or
  feasibility
• e.g., proof-of-concept model
• Communication
• demonstration of product for feedback
• e.g., 3D physical models of style or function
• Integration
• combination of sub-systems into system model
• e.g., alpha or beta test models
• Milestones
• goal for development teams schedule
• e.g., first testable hardware

Product Design and DevelopmentChapter 12 Karl T.
Ulrich and Steven D. Eppinger2nd Edition, Irwin
McGraw-Hill, 2000
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Physical vs. Analytical Prototypes

• Physical Prototypes
• Tangible approximation of the product.
• May exhibit unmodeled behavior.
• Some behavior may be an artifact of the
  approximation.
• Often best for communication.

• Analytical Prototypes
• Mathematical model of the product.
• Can only exhibit behavior arising from explicitly
  modeled phenomena.
• Some behavior may be an artifact of the
  analytical method.
• Often allow more experimental freedom than
  physical models.

Product Design and DevelopmentChapter 12 Karl T.
Ulrich and Steven D. Eppinger2nd Edition, Irwin
McGraw-Hill, 2000
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Focused vs. Comprehensive Prototypes

• Focused Prototypes
• Implement one or a few attributes of the product.
• Answer specific questions about the product
  design.
• Generally several are required.

• Comprehensive Prototypes
• Implement many or all attributes of the product.
• Offer opportunities for rigorous testing.
• Often best for milestones and integration.

Product Design and DevelopmentChapter 12 Karl T.
Ulrich and Steven D. Eppinger2nd Edition, Irwin
McGraw-Hill, 2000
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Physical Prototyping Options (1/2)

• Low Tech high skill
• clay, foam core - panels, wood, styrofoam
• High Tech (CAD via .stl)
• stereo lithography (SLA by 3-D Systems)
  (photosensitive resin)
• fused deposition (FDM by Stratasys) (extruded ABS
  resin)
• laminated object manufacturing (LOM) (glued
  sheets of paper)
• selective laser sintering (SLS) (sintered
  powdered metal

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FDM
SLA
SLS
SLS
Rapid Prototyping Center Milwaukee School of
Engineering
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Schematic of Stereo Lithography (SLA)
Malloy, Plastic Part Design for Injection
Molding, Fig. 5.10
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SLA can make objects that are virtually
impossible to manufacture.
Rapid Prototyping Center Milwaukee School of
Engineering
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Schematic of Fused Deposition Modeling (FDM)
Malloy, Plastic Part Design for Injection
Molding, Fig. 5.16
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Schematic of Laminated Object Manufacturing (LOM
by Helisys)
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Laminated Object Manufacturing (LOM) is cheaper
than SLS and can make prototypes for casting.
Rapid Prototyping Center Milwaukee School of
Engineering
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Schematic of Selective Laser Sintering (SLS)
Malloy, Plastic Part Design for Injection
Molding, Fig. 5.15
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Selective Laser Sintering (SLS) can be used for
injection molding tooling
Rapid Prototyping Center Milwaukee School of
Engineering
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Prototyping Options (2/2)

• Virtual
• stress analysis with finite element modeling,
• mold filling analysis with .stl mesh
• kinematic simulation (CAD)
• CNC Machining
• machine block of plastic for part, or
• machine simple aluminum mold for Morgan
• RTV Casting
• use SLA as pattern for room temperature
  vulcanizing rubber split mold

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Schematic of RTV Mold Casting (with SLA pattern)
SLA Pattern of Part to be copied with RTV mold
Cast (mold) parts with very real mechanical
properties to actual moldings.
Malloy, Plastic Part Design for Injection
Molding, Fig. 5.18
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Rapid Prototyping Costs / Quality

• Costs FDM lt LOM lt SLA lt SLS
• Quality LOM lt FDM lt SLA SLS
• Depending on part complexity CNC fabrication
  can compete with rapid prototyping.

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Prototyping Methods Summary

• Low Tech (requires skill to make)
• Foam blocks, clay
• RAPID (CAD via .stl)
• FDM (fused deposition modeling)
• LOM, SLA, SLS
• Durable prototypes
• CNC blocks to make parts
• RTV rubber molds to cast parts
• Virtual prototypes
• Stress analysis UG Stress Wizard
• Mold filling simulation (weld lines, tonnage)

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Questions?