This document provides guidance on conducting a Design Failure Mode and Effects Analysis (DFMEA). It begins with defining the purpose of a FMEA and what it involves. It then discusses current DFMEA practices and concerns. The remainder of the document offers detailed instructions on performing a DFMEA, including how to construct a process flow diagram, interface matrix, evaluate potential failure modes and their effects/severity, occurrence, detection, and risk priority numbers. It provides examples and criteria for properly analyzing risk and prioritizing corrective actions. The overall summary is that the document aims to refine the approach to DFMEAs by outlining the full process and key considerations for effectively conducting a thorough design risk assessment.

1. DFMEA

2. Purpose
To deepen understanding and refine
your current approach to Design
FMEA’s.

3. Definition of FMEA
A Failure Mode and Effect Analysis uses a
disciplined technique to identify and help eliminate
product and process potential failure modes.
o By ID of potential failures
o Assessing the risks caused by failure modes and Identify
corrective actions
o Prioritizing corrective actions
o Carry out corrective actions

4. Design FMEA's

5. Current practices/concerns?

7. DFMEA/PFMEA Information
Interrelationships
DFMEA
Design FMEA
Process Flow
Diagram
PFMEA
Process FMEA
Boundary (Block)
Diagram, P- Diagram,
Etc.
Design Verification
Plan & Report
(DVP&R)
Process Control
Plan

8. Potential Key Product Characteristics
Development
DetectPrevent
R
P
N
D
E
T
O
C
C
S
E
V
Action
Taken
Action Results
Response &
Target
Complete
Date
Recommended
Actions
R
P
N
D
e
t
e
c
Current
Controls
O
c
c
u
r
Potential
Cause(s)/
Mechanism(s)
Of Failure
C
l
a
s
s
S
e
v
Potential
Effect(s) of
Failure
Potential
Failure
Mode
Item /
Process
Step
DetectPrevent
R
P
N
D
E
T
O
C
C
S
E
V
Action
Taken
Action Results
Response &
Target
Complete
Date
Recommended
Actions
R
P
N
D
e
t
e
c
Current
Design
Controls
O
c
c
u
r
Potential
Cause(s)/
Mechanism(s)
Of Failure
C
l
a
s
s
S
e
v
Potential
Effect(s) of
Failure
Potential
Failure
Mode
Item /
Process
Step
Function
DFMEA
Requirements Documents
!
•Regulatory
•Dimensional
•Cosmetic
!
Req. Spec. Document
Drawings
Warranty History
Robustness Tools
!
Boundary Diagram
P-Diagram
Interface Matrix
10
9
8
7
6
5
4
3
2
1
1 2 3 4 5 6 7 8 9 10
S
E
V
E
R
I
T
Y
O C C U R R E N C E
POTENTIAL CRITICAL CHARACTERISTICS
Safety/Regulatory
POTENTIAL
SIGNIFICANT
CHARACTERISTICS
Customer Dissatisfaction
Special Characteristics Matrix
ANOYANCE
ZONE
ALL OTHER CHARACTERISTICS
Appropriate actions /
controls already in place
Cascade Technical
Requirements Into Special
Product Characteristics

9. Example analysis

10. Pencil Assembly

11. Block-Diagram

12. Step 2 P-diagram

13. Step 2 P-diagram

14. P-Diagram (Parameter diagram)
Example of a P-DIAGRAM

15. Interface matrix

16. Interface matrix

17. Functional requirements

18. Function and Mode

19. Function and Mode

20. Function and Mode

21. Effects and severity

23. Effects and severity

24. Severity Column
DetectPrevent
R
P
N
D
E
T
O
C
C
S
E
V
Action
Taken
Action Results
Response &
Traget
Complete
Date
Recommended
Actions
R
P
N
D
e
t
e
c
Current
Process
Controls
O
c
c
u
r
Potential
Cause(s)/
Mechanism(s)
Of Failure
C
l
a
s
s
S
e
v
Potential
Effect(s) of
Failure
Potential
Failure
Mode
Item /
Process
Step
DetectPrevent
R
P
N
D
E
T
O
C
C
S
E
V
Action
Taken
Action Results
Response &
Traget
Complete
Date
Recommended
Actions
R
P
N
D
e
t
e
c
Current
Process
Controls
O
c
c
u
r
Potential
Cause(s)/
Mechanism(s)
Of Failure
C
l
a
s
s
S
e
v
Potential
Effect(s) of
Failure
Potential
Failure
Mode
Item /
Process
Step
Function
Severity
Column

25. AUTOMOTIVE EXAMPLE SEVERITY EVALUATION CRITERIA
Hazardous-
with
warning
Very High
High
Very high severity ranking when a potential failure mode affects safe vehicle
operation and/or involves noncompliance with government regulation without
warning
Low
Very Low
Minor
Very Minor
None
Very high severity ranking when a potential failure mode affects safe vehicle
operation and/or involves noncompliance with government regulation with
warning
Vehicle/item inoperable (loss of primary function).
Vehicle/item operable but at a reduced level of performance. Customer very
dissatisfied.
Vehicle/item operable but Comfort/Convenience item(s) inoperable.
Customer dissatisfied.
Vehicle/item operable but Comfort/Convenience item(s) operable at a
reduced level of performance. Customer somewhat dissatisfied.
Fit & Finish/Squeak & Rattle item does not conform. Defect noticed by most
customers (greater than 75%).
Fit & Finish/Squeak & Rattle item does not conform. Defect noticed by 50%
of customers.
Fit & Finish/Squeak & Rattle item does not conform. Defect noticed by
discriminating customers (less than 25%).
No discernable effect.
10
8
7
6
3
2
1
Hazardous-
without
warning
Moderate
4
5
EFFECT CRITERIA: Severity of Effect
RNK.
SEVERITY EVALUATION CRITERIA
9

26. FMEA General
● For High Severity 9/10

29. Occurrence Column
DetectPrevent
R
P
N
D
E
T
O
C
C
S
E
V
Action
Taken
Action Results
Response &
Traget
Complete
Date
Recommended
Actions
R
P
N
D
e
t
e
c
Current
Process
Controls
O
c
c
u
r
Potential
Cause(s)/
Mechanism(s)
Of Failure
C
l
a
s
s
S
e
v
Potential
Effect(s) of
Failure
Potential
Failure
Mode
Item /
Process
Step
DetectPrevent
R
P
N
D
E
T
O
C
C
S
E
V
Action
Taken
Action Results
Response &
Traget
Complete
Date
Recommended
Actions
R
P
N
D
e
t
e
c
Current
Process
Controls
O
c
c
u
r
Potential
Cause(s)/
Mechanism(s)
Of Failure
C
l
a
s
s
S
e
v
Potential
Effect(s) of
Failure
Potential
Failure
Mode
Item /
Process
Step
Function
Occurrence
Column

30. Occurrence Evaluation Criteria
*Note: Zero (0) rankings for Severity, Occurrence or Detection are not allowed
Probability of Likely Failure Rates Over Design Life Ranking
Failure
SUGGESTED OCCURRENCE EVALUATION CRITERIA
Very High: Persistent failures
High: Frequent failures
Moderate: Occasional failures
Low: Relatively few failures
Remote: Failure is unlikely
≥ 100 per thousand vehicles/items
50 per thousand vehicles/items
20 per thousand vehicles/items
10 per thousand vehicles/items
5 per thousand vehicles/items
2 per thousand vehicles/items
1 per thousand vehicles/items
0.5 per thousand vehicles/items
0.1 per thousand vehicles/items
≤ 0.01 per thousand vehicles/items
10
9
8
7
6
5
4
3
2
1

31. Example of Significant/ Critical Threshold
*Used by permission of Ford Motor Company
10
9
8
7
6
5
4
3
2
1
1 2 3 4 5 6 7 8 9 10
S
E
V
E
R
I
T
Y
O C C U R R E N C E
POTENTIAL CRITICAL
CHARACTERISTICS Safety/Regulatory
POTENTIAL
SIGNIFICANT
CHARACTERISTICS
Customer Dissatisfaction
ALL OTHER CHARACTERISTICS
Appropriate actions /
controls already in place
Special Characteristics Matrix
ANOYANCE
ZONE

32. Design Verification (Current Design Controls)
▪ Think of Design Control in two ways; Prevention and
Detection. List them separately.
▪ To save time, add any new (untried) prevention/
detection ideas to the document under Recommended
Actions column.
o Prevention is specifically related to reduction or elimination of a
cause.
o Detection is how well the test or series of tests may find the
design flaw
– Causes
– Failure Mode

35. Detection Rating
Absolute
Uncertainty
Very Remote
Remote
Very Low
Low
Moderate
Moderately
High
High
Very High
Almost
Certain
10
9
8
7
6
5
4
3
2
1
Design Control will not and/or cannot detect a potential cause/ mechanism and
subsequent failure mode; or there is no
Design Control.
Very Remote chance the Design Control will detect a potential cause/
mechanism and subsequent failure mode.
Remote chance the Design Control will detect a potential cause/ mechanism
and subsequent failure mode.
Very Low chance the Design Control will detect a potential cause/mechanism
and subsequent failure mode.
Low chance the Design Control will detect a potential cause/mechanism and
subsequent failure mode.
Moderate chance the Design Control will detect a potential cause/ mechanism
and subsequent failure mode.
Moderately High chance the Design Control will detect a potential cause/
mechanism and subsequent failure mode.
Very High chance the Design Control will detect a potential cause/ mechanism
and subsequent failure mode.
High chance the Design Control will detect a potential cause/ mechanism and
subsequent failure mode.
Design Controls will almost certainly detect a potential cause/ mechanism and
subsequent failure mode.
DETECTION
SUGGESTED DETECTION EVALATION CRITERIA
CRITERIA RNK.

36. Analysis Of Risk
▪ RPN / RISK PRIORITY NUMBER
▪ What Is Risk?
▪ Probability of danger
▪ Severity/Occurrence/Cause

37. Evaluation by RPN Only
▪ Case 1
o S=5 O=5 D=2 RPN = 50
▪ Case 2
o S=3 O=3 D=6 RPN = 54
▪ Case 3
o S=2 O=10, D=10 = 200
▪ Case 4
o S=9 O=2 D=3 = 54
WHICH ONE
IS WORSE?

38. Example
▪ Extreme Safety/Regulatory Risk
o =9 & 10 Severity
▪ High Risk to Customer Satisfaction
o Sev. > or = to 5 and Occ > or = 4
▪ Consider Detection only as a measure of Test
Capability.

39. Example of Significant/ Critical Threshold
*Used by permission of Ford Motor Company
10
9
8
7
6
5
4
3
2
1
1 2 3 4 5 6 7 8 9 10
S
E
V
E
R
I
T
Y
O C C U R R E N C E
POTENTIAL CRITICAL
CHARACTERISTICS Safety/Regulatory
POTENTIAL
SIGNIFICANT
CHARACTERISTICS
Customer Dissatisfaction
ALL OTHER CHARACTERISTICS
Appropriate actions /
controls already in place
Special Characteristics Matrix
ANOYANCE
ZONE

40. Actions
Item
Function
System
Subsystem
Component:
Model Year/Vehicle (s):
Core Team:
Your Company Name Here Potential
Failure Mode and Effects Analysis
(Design FMEA)
Design Responsibility:
Key Date:
FMEA Number:
Page of
Prepared by:
FMEA Date (Orig.): (Rev.):
Potential
Failure
Mode
Potential
Effect (s) of
Failure
s
e
v
c
l
a
s
s
Potential
Cause (s)/
Mechanism (s)
Failure
o
c
c
u
r
Current
Design
Controls
D
e
t
e
c
R.
P.
N.
Recommended
Action(s)
Responsibility
& Target
Completion
Date
Actions
Taken
s
e
v
o
c
c
D
e
t
R.
P.
N.
A c t i o n R e s u l t s

41. Actions
EXAMPLE:
Project: Date Of
Meeting:
Issue
Number
Issue Status/
Open Date
Issue
Champion
Action
Number
Action
Date
Action Person Resp.
Team
Completion
Date
143

42. Re-rating RPN After Actions Have Occurred
Item
Function
System
Subsystem
Component:
Model Year/Vehicle (s):
Core Team:
Your Company Name Here Potential
Failure Mode and Effects Analysis
(Design FMEA)
Design Responsibility:
Key Date:
FMEA Number:
Page of
Prepared by:
FMEA Date (Orig.): (Rev.):
Potential
Failure
Mode
Potential
Effect (s) of
Failure
S
e
v
C
l
a
s
s
Potential
Cause (s)/
Mechanism (s)
Failure
O
c
c
u
r
Current
Design
Controls
D
e
t
e
c
R.
P.
N.
Recommended
Action(s)
Responsibility
& Target
Completion
Date
Actions
Taken
S
e
v
O
c
c
D
e
t
R.
P.
N.
A c t i o n R e s u l t s

43. Re-rating RPN After Actions Have Occurred
▪ Severity typically stays the same.
▪ Occurrence is the primary item to reduce / focus on.
▪ Detection is reduced only as a last resort.
▪ Do not plan to REDUCE RPN with detection actions!!!
o 100% inspection is only 80% effective!
o Reducing RPN with detection does not eliminate failure mode,
or reduce probability of causes
o Detection of 10 is not bad if occurrence is 1

44. FMEA in a continuous flow process
●Steel Making example:
!
▪ Design FMEA was performed on a Crankshaft to
determine the best material for the product being
considered. This was a critical application.
!
▪ Key features such as Geometry, Strength, Duty Cycle,
were described to the Steel producer.