Concept Selection

1
Concept Selection

• Chapter 7
• EIN 6392, Spring 2008
• Product Design for Manufacturability and
  Automation

2
Product Design and Development

• 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

3
Concept Development Process
Mission Statement
Development Plan
Identify Customer Needs
Establish Target Specifications
Generate Product Concepts
Select Product Concept(s)
Set Final Specifications
Plan Downstream Development
Test Product Concept(s)
Perform Economic Analysis
Benchmark Competitive Products
Build and Test Models and Prototypes
4
Outline

• Concept selection approaches
• Concept selection process
• Concept screening
• Concept scoring
• Caveats

5
Definition

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

6
Concept selection approaches

• External decision
• Product champion
• Intuition
• Pros and cons
• Prototype and test
• Decision matrices

7
Concept Selection Process

• Prepare the Matrix
• Criteria
• Reference Concept
• Weighing
• Rate Concepts
• Scale (//0) or (15)
• Compare to Reference Concept or Values
• Rank Concepts
• Sum Weighted Scores
• Combine and Improve
• Remove Bad Features
• Combine Good Qualities
• Select Best Concept
• May Be More than One
• Beware of Average Concepts
• Reflect on the Process
• Continuous Improvement

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Concept Development Funnel
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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!

10
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 criterion

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Concept screening steps

• Prepare a selection matrix based on the selection
  criteria
• Rate the concepts
• Rank the concepts
• Combine and improve concepts
• 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 products manufacturability
• Reduce lead time
• Encourage more and effective participation from
  the design team members
• Have better documentation of the decision
  process.

13
Concept scoring method

• where
• wi the weight for the ith criterion
• rij raw rating of concept j for the ith
  criterion

14
Issues in the decision process

• It assumes that the selection criteria reflect
  customers 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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Example Concept Screening
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Example Concept Scoring
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Concept Selection ExerciseMechanical Pencils
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Mechanical Pencils Customer Needs
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Mechanical PencilsConcept 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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Summary Caution

• Difficult to decompose the concept of quality
• Subjective criteria
• Systematically document concepts attributes that
  can facilitate improving concepts.
• Where to include cost
• Use of standard product configurations to
  evaluate concepts at component levels
• Repeat use of concept selection process as the
  design process proceeds to more detailed levels.