Prototyping

Teaching materials to accompany:Product Design and Development

Chapter 14Karl T. Ulrich and Steven D. Eppinger5th Edition, Irwin McGraw-Hill, 2012.

Product Design and DevelopmentKarl T. Ulrich and Steven D. Eppinger5th edition, Irwin McGraw-Hill, 2012.

Chapter Table of Contents:1.Introduction2.Development Processes and Organizations3.Opportunity Identification4.Product Planning5.Identifying Customer Needs6.Product Specifications7.Concept Generation8.Concept Selection9.Concept Testing10.Product Architecture11.Industrial Design12.Design for Environment13.Design for Manufacturing14.Prototyping15.Robust Design16.Patents and Intellectual Property17.Product Development Economics18.Managing Projects

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.

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

Prototyping Example:Apple PowerBook Duo Trackball

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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

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 team’s schedule– e.g., first testable hardware

Types of Prototypes

ComprehensiveFocused

Physical

Analytical

finalproduct

betaprototype

alphaprototype

ballsupport

prototype

simulationof trackball

circuits

equationsmodeling ball

supports

trackball mechanismlinked to circuit

simulation

notgenerallyfeasible

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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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Prototype decision (technical risk vs. 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

Physical vs. Analytical PrototypesPhysical 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.

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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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

Boeing 777 TestingBrakes 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?

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?).

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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Prototype technologies• Traditional prototyping methods• 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

Traditional Prototyping Methods

• CNC machining

• Rubber molding + urethane casting

• Materials: wood, foam, plastics, etc.

• Model making requires special skills.

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...

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...

BMW Virtual Crash Test

From: Scientific American, March 1999

Other Images

Prototyping

Chapter 12

EIN 6392, Product Design

summer 2012

04/18/23 43

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)