2. FAILURE MODE AND EFFECT ANALYSIS(FMEA)
Failure modes and effects analysis (FMEA) is a step-by-step
approach for identifying all possible failures in a design, a
manufacturing or assembly process, or a product or service.
Failure mode - the way in which something might fail
Effects analysis – studying the consequences of the various
failure modes to determine their severity to the customer.
3. Failure Mode
The way in which the product or process
could fail to perform its intended function.
Failure modes may be the result of
upstream operations or inputs, or may
cause downstream operations or outputs
to fail.
Failure Effects
The outcome of the occurrence of the
failure mode on the system, product, or
process.
Failure effects define the impact on the
customer.
Ranking is translated into “Severity”
score
4. Failure Causes
Potential causes or reasons the
failure mode could occur
Likelihood of the cause creating the
failure mode is translated into an
“Occurrence” score
Current Controls
Mechanisms currently in place that
will detect or prevent the failure
mode from occurring
Ability to detect the failure before it
reaches the customer is translated
in “Delectability” score
5. FMEA-HISTORY
1940s - First developed by the US
military in 1949 to determine the
effect of system and equipment
failures
1960s - Adopted and refined by NASA
(used in the Apollo Space program)
1970s – Ford Motor Co. introduces
FMEA after the Pinto affair. Soon
adopted across automotive industry
Today – FMEA used in both
manufacturing and service industries
6. 1. Bottom-up qualitative dependability analysis method.
2. Suited to the study of materials, component and equipment
failures and their effects on the next functional system level.
3. Involves examining each items, considering how that item can
fail and then determining how will affect the operations.
4. FMEA- used to identify potential failures modes, determine
their effects on the operation of the product and identify
actions to minimize the failures.
5. FMEA is a tool used to prevent problems from occurring.
FMEA
7. FMEA Steps
1. Identifies Design or process related Failure Modes before they
happen.
2. Determines the Effect of each failure mode.
3. Classify the failures by its effects on the system or machine.
4. Determine the failure probability of occurrence.
5. Identify how the failure mode can de detected.
6. Identify any compensate provisions or design changes.
7. Calculate the Risk Priority Number (RPN).
8. Develop recommended action, Assign responsible person and
take actions.
9. Assign the predicted severity, occurrence and detection levels
and compare RPN’s.
10.Develops & documents Action Plans that will occur to reduce
risk.
8. Risk Priority Number
The Risk Priority Number (RPN) identifies the greatest
areas of concern.
RPN is the product of:
(1) Severity rating
(2) Occurrence rating
(3) Detection rating
9. FMEA Types
1. System Focuses
2. Design Focuses
3. Process focuses
4. Service focuses
10. FMEA Application
1. In Process stage:
Analyze the manufacturing and assembly processes.
2. Design Stage:
Analyze products before they are released for production.
3. Conceptualization stage:
Analyze systems, sub systems in the early design stage.
4. Equipment:
Analyze machine equipment design before they are purchased.
5. Service stage:
Analyze service industries processes before they are released
to impact the customer.
11. FMEA- TERMINOLOGY
Failure Modes: (Specific loss of a function) is a concise description of how a
part , system, or manufacturing process may potentially fail to perform its
functions.
Failure Mode "Effect”: A description of the consequence or Ramification of a
system or part failure. A typical failure mode may have several “effects”
depending on which customer you consider.
Severity Rating: (Seriousness of the Effect) Severity is the numerical rating of
the impact on customers.
Failure Mode "Causes”: A description of the design or process deficiency
(global cause or root level cause) that results in the failure mode
Occurrence Rating: Is an estimate number of frequencies or cumulative
number of failures (based on experience) that will occur (in our design
concept) for a given cause over the intended “life of the design”.
Failure Mode "Controls”: The mechanisms, methods, tests, procedures, or
controls that we have in place to PREVENT the Cause of the Failure Mode or
DETECT the Failure Mode or Cause should it occur .
12. FMEA-TERMINOLOGY
Detection Rating: A numerical rating of the probability that a given set
of controls WILL DISCOVER a specific Cause of Failure Mode to prevent
bad parts leaving the facility or getting to the ultimate customer.
Risk Priority Number (RPN): Is the product of Severity, Occurrence, &
Detection. Risk= RPN= S x O x D
Action Planning: A thoroughly thought out and well developed FMEA
With High Risk Patterns that is not followed with corrective actions has
little or no value, other than having a chart for an audit
13. Linking Causes to Effects
One to One, One to Many, Many to One, or Many to Many
Cause 1
Cause 2
Effect 1
Effect 2
Cause 1
Effect 1
Effect 2
Cause 1
Cause 2
Effect 1
1:1
1:M
M:1
14. FMEA Process
Start with the
process map
1 For each step,
brainstorm
potential failure
modes and effects
2
Determine the
potential causes to
each failure mode
3
Evaluate current
controls
4
Determine
severity
Determine
likelihood of
occurrence
Determine
detectability
Determine RPN
5
Identify actions
6
15. FMEA - BENEFITS
Identify potential and known failures
Reduce the number of engineering changes
Reduce product development time
Lower start-up costs
Greater customer satisfaction
Increased cooperation and teamwork between various functions
Continuous improvement
Reduced risk
Improve Quality, Reliability and safety
22. Example
Purchasing Dept.
Determine how likely
the controls in place
will detect or prevent
the failure mode from
occurring
Identify what controls
or measures are
currently in place
25. Example
Purchasing Dept.
Brainstorm
potential actions
that will lower the
RPN
Assign
specific
owners
FMEA owner &
team update
the document
as actions are
complete
Recalculate
the RPN after
actions are
complete
Occurrence Reduced from 4 to 3.
PRN cut in half.
26.
27. Ford workers were afraid to talk to Iacocca about the
safety defects
In Feb. 1978, Ford was sued for $128 million – more then
3 times the amount they had predicted
May 1978 – Department of Transportation announces
defects with the Ford Pinto – Ford recalls 1.5 million
Pintos
Mar. 1980 – Ford was charged with reckless homicide –
acquitted of charges, however they stopped all Pinto
production
What Happened
