prototyping chapter 12 ein 6392, product design summer 2012
TRANSCRIPT
Prototyping
Chapter 12EIN 6392, Product Design
summer 2012
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Product Design and DevelopmentKarl T. Ulrich and Steven D. EppingerChapter Table of Contents 1. Introduction2. Development Processes and Organizations3. Product Planning4. Identifying Customer Needs5. Product Specifications6. Concept Generation7. Concept Selection8. Concept Testing9. Product Architecture10. Industrial Design11. Design for Manufacturing12. Prototyping13. Product Development Economics 14. Managing Projects
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Concept Development Process
Perform Economic Analysis
Benchmark Competitive Products
Build and Test Models and Prototypes
IdentifyCustomer
Needs
EstablishTarget
Specifications
GenerateProduct
Concepts
SelectProduct
Concept(s)
Set Final
Specifications
PlanDownstreamDevelopment
MissionStatement Test
ProductConcept(s)
DevelopmentPlan
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PlanningPlanning
Product Development Process
ConceptDevelopment
ConceptDevelopment
System-LevelDesign
System-LevelDesign
DetailDesign
DetailDesign
Testing andRefinement
Testing andRefinement
ProductionRamp-Up
ProductionRamp-Up
Prototyping is done throughout the development process.
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Outline Definition Steps in prototyping decisions Purposes of prototypes Principles for choosing a prototype
type
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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
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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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Types of Prototypes
ComprehensiveFocused
Physical
Analytical
finalproduct
betaprototype
alphaprototype
Physical models of components
Simulation modelsof product components
equationsmodeling components
Components linked to other components or
models
notgenerallyfeasible
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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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Purposes vs. prototype types Focused analytical
Learning Focused physical
Learning and communication Comprehensive physical
Learning, communication, integration, and milestones.
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Technical risk vs. comprehensive prototype cost Low risk- low cost (e.g., printed matters)
No need for comprehensive prototypes Low risk – high cost (ships, buildings)
Can’t afford comprehensive prototype. High risk – low cost (software)
Many comprehensive prototypes High risk high cost (airplanes, satellites)
Use analytical models extensively Carefully planned comprehensive prototypes Sell the first unit
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Physical vs. Analytical PrototypesPhysical Prototypes Tangible approximation
of the product. May exhibit un-modeled
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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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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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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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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Prototyping Example:Apple PowerBook Duo Trackball
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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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Comprehensive Prototypes
Cost of Comprehensive PrototypeHighLow
Tec
hn
ical
or
Mar
ket
Ris
k
Hig
hL
ow
One prototype may be used for verification.
Few or no comprehensiveprototypes are built.
Many comprehensiveprototypes are built.
Some comprehensiveprototypes build (and sold?).
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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 sufficient time to learn from prototype cycles.
Avoid the “hardware swamp”.
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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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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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BMW Virtual Crash Test
From: Scientific American, March 1999
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Traditional Prototyping Methods
CNC machining Rubber molding + urethane casting
Materials: wood, foam, plastics, etc. Model making requires special skills.