1. Chapter 12 EIN 6392, Product Design Fall 2009
Prototyping
Chapter 12
EIN 6392, Product Design
Fall 2009

2. Product Design and Development Karl T. Ulrich and Steven D
Product Design and Development Karl T. Ulrich and Steven D. Eppinger 2nd edition, Irwin McGraw-Hill, 2000.
Chapter Table of Contents
1. Introduction
2. Development Processes and Organizations
3. Product Planning
4. Identifying Customer Needs
5. Product Specifications
6. Concept Generation
7. Concept Selection
8. Concept Testing
9. Product Architecture
10. Industrial Design
11. Design for Manufacturing
12. Prototyping
13. Product Development Economics
14. Managing Projects
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3. Product Development Process
Planning
Concept
Development
System-Level
Design
Detail
Design
Testing and
Refinement
Production
Ramp-Up
Prototyping is done throughout the development process.
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4. Concept Development Process
Mission
Statement
Development
Plan
Identify
Customer
Needs
Establish
Target
Specifications
Generate
Product
Concepts
Select
Product
Concept(s)
Test
Product
Concept(s)
Set Final
Specifications
Plan
Downstream
Development
Perform Economic Analysis
Benchmark Competitive Products
Build and Test Models and Prototypes
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5. Outline Definition Steps in prototyping decisions
Purposes of prototypes
Principles for choosing a prototype type
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6. Definition
An approximation of the product along one or more dimensions of interest.
Physical prototypes vs. analytical prototypes
Comprehensive (with all the attributes of a product) vs. focused
See Exhibit 12-5 on page 250 for the types of prototypes
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7. Purposes of prototypes
Learning
Learn whether it will work and how well it will meet the customer needs
Communication
Communicate with top management, vendors, partners, extended team members, customers, and sources of financing.
Integration
Integrate into the product assembly to ensure that components or subsystems fit well into the product design.
Milestones
Establish milestones for demonstrating that the product has achieved a desired level of functionality.
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8. Types of Prototypes Physical Focused Comprehensive Analytical not
alpha
prototype
beta
prototype
ball
support
prototype
final
product
trackball mechanism
linked to circuit
simulation
Focused
Comprehensive
simulation
of trackball
circuits
not
generally
feasible
equations
modeling ball
supports
Analytical
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9. Principles for choosing a prototype type
Analytical prototypes are in general more flexible than physical prototypes
Physical prototypes are required to detect unanticipated phenomena
Prototypes may reduce the risk of costly iterations
Prototypes may expedite other development steps
Example: add a prototyping step in the part design-mold design-molding process
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10. Purposes vs. prototype types
Focused analytical
Learning
Focused physical
Learning and communication
Comprehensive physical
Learning, communication, integration, and milestones.
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11. Technical risk vs. comprehensive prototype cost
Low risk- low cost (printed matters)
Use one or no comprehensive prototypes
Low risk – high cost (ships, buildings)
Build no compre. prototype.
High risk – low cost (software)
Many comprehensive prototypes
High risk high cost (airplanes, satellites)
Use analytical models extensively
Carefully planned compre. Prototypes
Sell the first unit
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12. 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. (However, behavior is not always anticipated.
Some behavior may be an artifact of the analytical method.
Often allow more experimental freedom than physical models.
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13. 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.
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14. Prototype technologies
3D computer modeling
Free-form fabrication
Stereolithography
Using various materials including wax, resin, paper, ceramics, and metals.
Lamination
Using paper cut, lay by layer
Rapid prototyping
Laser curing (solidifying) soft materials such as resin, layer by layer
3D printing
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15. Steps Define the purpose of the prototype
Establish the level of approximation of the prototype
Outline an experimental plan
Create a schedule for procurement, construction, and test
Plan milestones for prototypes (alpha, beta, pre-production)
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16. Prototyping Example: Apple PowerBook Duo Trackball
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17. Boeing 777 Testing Brakes Test Minimum rotor thickness
Maximum takeoff weight
Maximum runway speed
Will the brakes ignite?
Wing Test
Maximum loading
When will it break?
Where will it break?
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18. Comprehensive Prototypes
Many comprehensive
prototypes are built.
Some comprehensive
prototypes build (and sold?).
High
Technical or Market Risk
One prototype may be
used for verification.
Few or no comprehensive
prototypes are built.
Low
Low
High
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Cost of Comprehensive Prototype

19. Prototyping Strategy Use prototypes to reduce uncertainty.
Make models with a defined purpose.
Consider multiple forms of prototypes.
Choose the timing of prototype cycles.
Many early models are used to validate concepts.
Relatively few comprehensive models are necessary to test integration.
Plan time to learn from prototype cycles.
Avoid the “hardware swamp”.
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20. Rapid Prototyping Methods
Most of these methods are additive, rather than subtractive, processes.
Build parts in layers based on CAD model.
SLA=Stereolithogrpahy Apparatus
SLS=Selective Laser Sintering
3D Printing
LOM=Laminated Object Manufacturing
Others every year...
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21. Virtual Prototyping 3D CAD models enable many kinds of analysis:
Fit and assembly
Manufacturability
Form and style
Kinematics
Finite element analysis (stress, thermal)
Crash testing
more every year...
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22. From: Scientific American, March 1999
BMW Virtual Crash Test
From: Scientific American, March 1999
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23. Traditional Prototyping Methods
CNC machining
Rubber molding + urethane casting
Materials: wood, foam, plastics, etc.
Model making requires special skills.
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