Concept Selection Chapter 7 EIN 6392, Summer 2012 Product Design for Manufacturability and...

Concept Selection

Chapter 7

EIN 6392, Summer 2012

Product Design for Manufacturability and Automation

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Product Design and Development

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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Outline

• Introduction to product concept selection

• Commonly dysfunctions in product development

• Product concept selection process

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Definition

• Product concept selection is a decision process, in which the design team selects one or a few product concept for further development

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Concept Selection Approaches• External decision

– By use of an external group of customers, clients, etc.

• Product champion & intuition

– By an influential member of the development team

• Multi-voting

– Asking each member to pick a number of concepts and pick the one with most votes.

• Pros and cons

– The team list the strengths and weakness of each concept.

• Prototype and test

– Build and test prototype for each concept and select based on the test data.

• Decision matrices

– The team rates each concept against selection criteria with varying importance/weights.

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Two stages of concept selection

• Concept screening (the Pugh concept selection method)– To quickly narrow the number of concepts and to

improve the concepts

• Concept scoring– weighs the relative importance of the selection

criteria– focus on more refined comparisons with respect to

each criteria

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Concept Selection Process1. Prepare the Matrix

– Criteria– Reference Concept– Weightings

2. Rate Concepts– Scale (– 0 +) or (1–5)– Compare to Reference Concept or Values

3. Rank Concepts– Sum Weighted Scores

4. Combine and Improve– Remove Bad Features– Combine Good Qualities

5. Select the Best Concept– May Be More than One– Beware of Average Concepts

6. Reflect on the Process– Continuous Improvement

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Concept Development Funnel

concept generation

concept screening

concept scoring

concept testing

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Remember…

The goal of concept selection is not to• Select the best concept.

The goal of concept selection is to• Develop the best concept.

So remember to combine and refine the concepts to develop better ones!

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Concept screening steps

1. Prepare a selection matrix based on the selection criteria

2. Rate the concepts

3. Rank the concepts

4. Combine and improve concepts

5. select one or more concepts

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Concept screening principles

• Be focused on customer needs• Match or exceed competitors’ performance along key

dimensions• Improve the product’s manufacturability• Reduce lead time• Encourage more and effective participation from the

design team members• Have better documentation of the decision process.

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Concept Scoring Method

– where

• wi = the weight for the ith criterion

• rij = raw rating of concept j for the ith criterion

i

n

iijj wrS

1

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Issues in the decision process• It assumes that the selection criteria reflect customer’s needs

• It assumes that the selection criteria are independent

• Manufacturing costs and manufacturability are not included in the decision

• It is better to directly evaluate those independent, simpler concepts underpinning the design concepts, if they constitute all the product concepts.

• The process of concept selection can be applied to throughout the development process.

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Concept Selection Example: Reusable Syringe

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Mission Statement

• Product description:– Reusable syringe with precision dosage

control for outpatient use.

• Primary market– Elderly

• Major features:– Accuracy of dose metering– Inexpensive

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Need analysis

• Ease of handling

• Ease of use

• Readability of dose settings

• Accuracy of dose metering

• Durability

• Ease of manufacture

• Portability

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Challenges

• How to choose the best concept of abstraction?

• How to embrace all inputs (likings and concerns) from the whole team in the decision process?

• How to make use of good attributes of otherwise weak concept designs?

• How to document the decision process?

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Example: Concept Screening

CONCEPT VARIANTS

SELECTIONCRITERIA A B C D E F G REF.

Ease of Handling 0 0 – 0 0 – – 0Ease of Use 0 – – 0 0 + 0 0Number Readability 0 0 + 0 + 0 + 0Dose Metering + + + + + 0 + 0Load Handling 0 0 0 0 0 + 0 0Manufacturing Ease + – – 0 0 – 0 0Portability + + – – 0 – – 0

PLUSES 3 2 2 1 2 2 2SAMES 4 3 1 5 5 2 3

MINUSES 0 2 4 1 0 3 2

NET 3 0 –2 0 2 –1 0RANK 1 3 7 5 2 6 4

CONTINUE? Yes Yes No No Yes No Yes

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Scale for Rating the Concepts

1: much worse than the reference

2: worse than the reference

3: same as the reference

4: better than the reference

5: much better than the reference

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Example: Concept ScoringConcepts

A DF E G+

Master Cylinder Lever Stop Swash Ring Dial Screw+

Selection Criteria Weight RatingWeighted

Score RatingWeighted

Score RatingWeighted

Score RatingWeighted

Score

Ease of Handling 5% 3 0.15 3 0.15 4 0.2 4 0.2

Ease of Use 15% 3 0.45 4 0.6 4 0.6 3 0.45

Readability of Settings 10% 2 0.2 3 0.3 5 0.5 5 0.5

Dose Metering Accuracy 25% 3 0.75 3 0.75 2 0.5 3 0.75

Durability 15% 2 0.3 5 0.75 4 0.6 3 0.45

Ease of Manufacture 20% 3 0.6 3 0.6 2 0.4 2 0.4

Portability 10% 3 0.3 3 0.3 3 0.3 3 0.3

Total Score

Rank

Continue? No Develop No No

(reference)

2.75

4

3.45

1

3.10

2

3.05

3

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Concept Selection Exercise:Mechanical Pencils

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Mechanical Pencils: Customer Needs

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Mechanical Pencils:Concept Selection Matrix

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Retail Prices of Five Pencils

• Classic $2.75

• Quick Click $2.58

• Twist Erase $2.08

• Zézé $0.90

• Bic $0.33

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Caveats

• Beware of the best "average" product.• Perform concept selection for each different

customer group and compare results.• Check sensitivity of selection to the

importance weightings and ratings.• May want to use all of detailed requirements in

final stages of selection.• Note features which can be applied to other

concepts.