IDENTIFY
OPPORTUNITY
GATHER
INFO
DEFINE
PROBLEM
GENERATE
CONCEPTS
SCREEN
CONCEPTS
IMPLEMENT
ME 4054W:
DESIGN PROJECTS
Week 6 – Tuesday
Concept Selection
Reference: Ulirich & Eppinger, Chapter 7
HANDOFF
Class Agenda
• Methods of Concept Screening
• Concept Screening (Pugh) Matrix
• Concept Scoring (Decision) Matrix
2
Concept Selection
• While concept generation is easy (and fun),
concept selection is difficult (and fun)
• You never have enough information; you must
make informed decisions nonetheless
• You will likely use estimation, analysis, and
some prototyping to complete the selection
process
• Weed out bad (vs. picking “best”)
• Look for new concepts and synergies during
the process
3
Concept Selection
• Start with a Product Design Specification
(PDS) that is finalized
• Examine ALL concepts at the same time
Documenting the selection process
is nearly as important as the result
(and must be included in your design report)
4
Concept Selection - Pictorially
Controlled
convergence
5
Exhibit 7-4
“Product Design and Development” by Ulrich and Eppinger
WRONG WAYS TO DO SCREENING
• Gut feel
• Boss says, “Do it this way”
• Single customer decides
• One team member is strong champion
• Influence of experienced designer
6
BETTER WAYS TO SCREEN CONCEPTS
• Multi-voting
– Each team member votes for several concepts.
The concept with the most votes is selected.
• Pros and cons
– The team lists the strengths and weaknesses of
each concepts. The group then selects the best
concept based on group opinion.
• Prototype and test
– Prototypes of each concept are built and tested;
the test data is used to make the selection
7
PREFERRED Concept Selection Process
• Decision Matrices
– Start with a Product Design Specification
– Examine ALL concepts at the same time
– Can be weighted or unweighted
Decision matrices are
a required method
in this course
8
Selection Criteria
Concepts
A
(reference)
B
C
D
E
1
0
+
-
0
-
2
0
+
+
-
-
3
0
-
0
+
0
4
0
+
0
0
+
Benefits of a Structured Concept
Selection Method
• A customer-focused product
• A competitive design
• Better product-process coordination
• Reduced time to product introduction
• Effective group decision making
• Documentation of the decision process
9
Two Stages of Concept Selection
1. Concept screening
• Reduce the many product concept ideas
generated to a relative few that will get
additional refinement and analysis
2. Concept scoring
• Use objective methods to select to your
consensus final concept selection
10
Concept Screening
1. Prepare the selection/screening matrix
• Selection criteria must relate to key customer needs
2. Rate the concepts
• + = “better than”
• 0 = “same as”
• − = “worse than”
3. Rank the concepts
• As objectively as possible using the concept rating
11
Concept Screening
4. Combine and improve the concepts
• Is there a generally good concept that is downgraded
by one feature?
• Can two concepts be combined to preserve the
“better than” features while simultaneously removing
any “worse than” features?
5. Select one or more concepts for further
refinement and analysis
6. Reflect on the results and process
• Are all team members “comfortable” with the
decisions? If not, what needs to be resolved?
12
Concept Screening Matrix Example
Exhibit 7-5
“Product Design and Development”
By Ulrich and Eppinger
13
Stage 2: Concept Scoring
1. Prepare the selection matrix
•
•
An optimized version of the concept screening matrix
Determine % weighting for each selection criteria
2. Rate the concepts
14
Page 135
“Product Design and Development”
By Ulrich and Eppinger
Concept Scoring
3. Rank the concepts
15
Page 136
“Product Design and Development”
By Ulrich and Eppinger
Concept Scoring
4. Combine and improve the concepts
5. Select one or more concepts for
further refinement and analysis
•
•
Sensitivity analysis
Build and test prototypes
6. Reflect on the results and process
•
16
Down-select to the consensus final concept
selection
Concept Scoring Example
Sensitivity analysis on criteria
weighting can provide insight
17
Exhibit 7-7
“Product Design and Development”
By Ulrich and Eppinger
Project Example:
Heated Veneer Press, Spring 2000
• Specifications taken from the product design specification
• If a specification does not differentiate one implementation
over another, remove it from the selection chart
• Limit specifications to 10 or less of the most important
• New specifications may arise associated with
manufacturability, etc. Add them to your PDS!
18
PDS (Abbreviated):
Veneer Press
19
Need #'s
Metric
Importance
Units
Marginal Value
Ideal Value
5
Surface flatness
5
mm/m
< 2.0
< 1.0
10
Cost
3
US $
< 800
400
4
Laminating
pressure
5
kPa
50-60
50-100
12
Pressure
variation over
panel surface
4
kPa
< 40
< 20
9
Duration of
pressure
application
3
hours
0-2
0-24
8
Set-up time
2
min
< 30
< 10
7
Loading time
3
minutes
< 10
<1
Concept Scoring Matrix:
Veneer Press
Criteria
Weighting
Factor
Roller
Clamp
Dead Weight
Vacuum
Surface flatness
25
2
5
5
2
Pressure variation over
panel surface
20
2
5
5
4
Duration of pressure
application
20
1
5
5
5
Loading time
15
3
5
4
3
Set-up time
10
5
4
4
3
Cost
10
5
3
4
2
Total score
100
255
470
465
325
4
1
2
3
Rank
If the total scores of two or more concepts are close
(as above), you can add selection criteria from your
PDS, do a sensitivity analysis or do both.
20
Concept Selection Exercise
• Review your PDS
• Identify specs to include on concept
selection matrices
• If time allows, begin creating a concept
screening matrix
– Most promising concepts across the top
– Most important specs on the side
(5 minutes)
21
Commons Pitfalls in Concept Selection
•
•
•
•
•
•
•
•
•
22
Not doing it
Running with the first idea
Forgetting the customer
Selection chart criteria don't correspond to PDS
Letting an "experienced" designer make the
choices
Going by gut feel
Letting a manager decide
Not buying into the process as a team
Ignoring cost
Congratulations!
IDENTIFY
OPPORTUNITY
GATHER
INFORMATION
DEFINE
PROBLEM
GENERATE
CONCEPTS
SCREEN
CONCEPTS
IMPLEMENT
• After following the structured process, you are
now ready to implement a design solution that
addresses the customer’s needs (PDS).
• Implementation includes, but is not limited to:
–
–
–
–
–
23
Design and analysis
Fabrication of prototype(s)
Testing
Optimization
Documenting the design and design process
HANDOFF