Failure Mode Effects Analysis FMEA A systematic group of activities intended to: Recognize the potential failure(s) of a product or process and the severity of effect of that failure(s). Identify critical characteristics. Rank order potential design and process deficiencies. Identify actions that can eliminate or reduce the chance of the potential failure from occurring and reaching the customer. Document the process. A living document.
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Failure Mode Effects Analysis
FMEA A systematic group of activities intended to:
Recognize the potential failure(s) of a product or process and the severity of effect of that failure(s).
Identify critical characteristics. Rank order potential design and process deficiencies. Identify actions that can eliminate or reduce the chance of
the potential failure from occurring and reaching the customer.
Document the process. A living document.
Failure Mode Effects Analysis
Guided by Customer Requirements Customers are internal Customers are external
Focus is on risk reduction with Design Manufacturing
Failure Mode Effects Analysis
Ideally used before a failure mode is unknowingly designed into a product or process.
Is also very useful with existing processes and products. Intended to be an interactive process that never ends. (Living
Document) Requires a cross functional, multi-level team approach. Supports Duracell Planning for Quality (DPQ) phases II and III.
Failure Mode Effects Analysis
FMEA Types System
Focus is on functions and interactions among systems.
Design Focus is on potential failure modes of products due to
design deficiencies and errors.
Process Focus is on potential failure modes caused by process
deficiencies.
FMEA Process
Team Selection
CalculateRisk Numbers
Define Process
DetailFailure Mode
CausesEffects
BuildPareto Chart
DevelopRecommended
Actions
FMEA Process
Team Selection
CalculateRisk Numbers
Define Process
DetailFailure Mode
CausesEffects
BuildPareto Chart
DevelopRecommended
Actions
FMEA Process
Team Selection
Cross Functional and Multilevel Operators, Mechanics, Engineers, Leaders Team Leader Designated Must be Empowered to implement actions
FMEA Process
Team Selection
CalculateRisk Numbers
Define Process
DetailFailure Mode
CausesEffects
BuildPareto Chart
DevelopRecommended
Actions
FMEA Process
Define Process
Develop a Process Flow diagram that is representative of the process as it truly is.
FMEA Process
Team Selection
CalculateRisk Numbers
Define Process
DetailFailure Mode
CausesEffects
BuildPareto Chart
DevelopRecommended
Actions
FMEA Process
DetailFailure Mode
CausesEffects
Brainstorm failure modes. Select and define failure modes that impact
critical characteristics. Identify root causes. Define effects of failure mode. Determine how often failure modes occur. Determine current controls ability to detect.
FMEA Process
Team Selection
CalculateRisk Numbers
Define Process
DetailFailure Mode
CausesEffects
BuildPareto Chart
DevelopRecommended
Actions
FMEA Process
CalculateRisk Numbers
Calculate Risk Priority Number (RPN) for each failure mode.
RPN = Worst severity x most frequent occurrence x worst ability to detect.
FMEA Process
Team Selection
CalculateRisk Numbers
Define Process
DetailFailure Mode
CausesEffects
BuildPareto Chart
DevelopRecommended
Actions
FMEA Process
BuildPareto Chart
Build Pareto’s One for Severity One for Severity x Occurrence One for RPN
Identify “Vital Few” Failure Modes
FMEA Process
Team Selection
CalculateRisk Numbers
Define Process
DetailFailure Mode
CausesEffects
BuildPareto Chart
DevelopRecommended
Actions
FMEA Process
DevelopRecommended
Actions
Develop and implement actions on “Vital Few” Failure Modes
FMEA Process
Team Selection
CalculateRisk Numbers
Define Process
DetailFailure Mode
CausesEffects
BuildPareto Chart
DevelopRecommended
Actions
FMEA Process
Evaluate effect of actions taken on process in terms of severity, occurrence and detection.
Recalculate RPN and reassess risk number. Reprioritize and repeat.
CalculateRisk Numbers
DetailFailure Mode
CausesEffects
BuildPareto Chart
DevelopRecommended
Actions
FMEA Format
Process Process Responsibility Page 1 of 1Cell Size FMEA Due Date Prepared byCell Chemistry FMEA Number FMEA Date (Orig.) (Rev.)
Action ResultsProcessFunction
PotentialFailureMode
PotentialEffect(s) of
Failure
Sev
Class
Potentialcause(s) of
Failure
Occ
CurrentControls
Det
S*O
RPN
RecommendedAction(s)
Area/IndividualResponsible &
Completion DateActions Taken s
ev
occ
det
S*O
RPN
Process Process Responsibility Page 1 of 1Cell Size FMEA Due Date Prepared byCell Chemistry FMEA Number FMEA Date (Orig.) (Rev.)
Severity Rating
Severity
Severity is a rating corresponding to the seriousness of an effect of a potential failure mode.
No Effect 1 No effect on system or output performance or on subsequent processes. Very Slight Effect 2 Customer will probably not notice the failure. Nuisance Fault noticed. Slight Effect 3 Slight effect on output performance. Customer slightly annoyed. Nuisance
fault obvious. Minor Effect 4 Minor effect on output or process performance. Slight deterioration. Chronic
nuisance fault. Moderate Effect 5 Moderate effect on performance. Customer dissatisfied. Nuisance repair
required. Significant Effect 6 Performance degraded but safe. Discomfort. Repair required. Non-vital
part nonfunctional. Major Effect 7 Rework/Repairs necessary. Performance severely affected but safe.
Dissatisfied customer. Subsystem inoperable. Serious Effect 8 Equipment damaged. System inoperable but safe. Very dissatisfied
customer. Very Serious Effect
9 Potentially hazardous failure. Safety related but gradual failure.
Hazardous Effect 10 Hazardous failure. Safety related – sudden failure, Government regulation non-compliance.
Severity
Severity is a rating corresponding to the seriousness of an effect of a potential failure mode.
No Effect 1 No effect on system or output performance or on subsequent processes.Very Slight Effect 2 Customer will probably not notice the failure. Nuisance Fault noticed.Slight Effect 3 Slight effect on output performance. Customer slightly annoyed. Nuisance
fault obvious.Minor Effect 4 Minor effect on output or process performance. Slight deterioration. Chronic
nuisance fault.Moderate Effect 5 Moderate effect on performance. Customer dissatisfied. Nuisance repair
required.Significant Effect 6 Performance degraded but safe. Discomfort. Repair required. Non-vital
part nonfunctional.Major Effect 7 Rework/Repairs necessary. Performance severely affected but safe.
Dissatisfied customer. Subsystem inoperable.Serious Effect 8 Equipment damaged. System inoperable but safe. Very dissatisfied
customer.Very SeriousEffect
9 Potentially hazardous failure. Safety related but gradual failure.
Hazardous Effect 10 Hazardous failure. Safety related – sudden failure, Government regulationnon-compliance.
Severity Rating
Occurrence
Occurrence is a rating corresponding to the rate at which a failure mode occurs before anydetecting measures are applied.Occurrence Rating Cpk Failure Rate NotesAlmostImpossible
1 Cpk 1.67 5.0 1 in1,500,000
Failure unlikely. Similar processes orproducts show no failure.
Remote 2 Cpk 1.50 4.5 1 in 150,000 Remote number of failures likely.Very Slight 3 Cpk 1.33 4.0 1 in 15,000 Very few failures likely.Slight 4 Cpk 1.17 3.5 1 in 2000 Few failures likely.Low 5 Cpk 1.00 3.0 1 in 400 Occasional failure.Medium 6 Cpk 0.83 2.5 1 in 80 Moderate number of failures likely.ModeratelyHigh
7 Cpk 0.67 2.0 1 in 20 Frequent failures likely.
High 8 Cpk 0.51 1.5 1 in 7 High number of failures likely.Very High 9 Cpk 0.33 1.0 1 in 3 Very high number of failures likely.AlmostCertain
10 Cpk0.33 1.0
1 in 3 Failures almost certain to occur.Similar processes/products showfailures.
Occurrence Rating
DetectionDetection is a rating corresponding to the likelihood that the detection methods or currentcontrols will detect the failure.Almost Certain 1 Reliable detection controls are known with similar processes or
products. Controls are almost certain to detect the failure mode.Very High 2 History with similar processes available. Controls very likely to
detect the failure modeHigh 3 Controls highly likely to detect the failure mode.Moderately High 4 Controls likely to detect the failure mode.Medium 5 Controls might detect the failure mode.Low 6 Low likelihood that controls will detect the failure mode.Slight 7 Slight likelihood that controls will detect the failure mode.Very Slight 8 Very slight likelihood that controls will detect the failure mode.Remote 9 Remote likelihood that controls will detect the failure mode.AlmostImpossible
10 Almost certain that controls will not detect the failure mode. Noknown controls available to do so.
Detection Rating
PotentialFailure Mode and Effects Analysis
Process FMEASystem - 4/3A Li Ion Cell Process Responsibility - Sunil Dhage FMEA # 97-08-01
Subsystem - Laser Weld Pressure Plate toInterrupter
Key Date Page # 1
Component - Pressure Plate/Thermal Interrupter Prepared by: T. Pratt, Shawn Stone, Sunil DhageMaster Drawing # 364140 FMEA Date Orig. 8/5/97 (Rev)Core Team: Manufacturing Development FILE NAME - C:\data\fmea\ppintlsr.sam
ProcessFunction /Reqs.
Potential FailureMode
Potential Effect(s) ofFailure
Sev
Class
Potential Cause(s) /Mechanismsof Failure
Occur
Current Process Controls Detect
RPN
Recommended Action Responsibility andtarget complete date
ActionTaken
Sev
Occ
Detect
RPN
Laser WeldPressure Plateto ThermalInterrupter
Completely fails toweld. (presumesautomatedequipment in use)
scrap 8 Poor placement ofcomponents in tooling
4 Vision systemImpedance checkOCV check
1 32
Contamination onparts
3 Incoming InspectionOperator Inspection
1 24
Parts not sitting flat 3 Height CheckOperator Inspection
1 24
Machine set up wrong 2 Operator InspectionSPC
1 16
Components out oftolerance
4 Incoming Inspection 1 32
Welder fails to cycle 2 Operator InspectionImpedance CheckOCV Check
1 16
Burn Through loss of hermeticitydamage to devicesafety issuesleakage
10 Incorrect settings 3 Vision systemVisual check after thermaltreatment cycle
4 120
non conforming parts 3 Incoming Inspection 4 120
Example FMEA
PotentialFailure Mode and Effects Analysis
Process FMEASystem - 4/3A Li Ion Cell Process Responsibility - Sunil Dhage FMEA # 97-08-01Subsystem - Laser Weld Pressure Plate toInterrupter
Key Date Page # 2
Component - Pressure Plate/Thermal Interrupter Prepared by: T. Pratt, Shawn Stone, Sunil DhageMaster Drawing # 364140 FMEA Date Orig. 8/5/97 (Rev)Core Team: Manufacturing Development FILE NAME - C:\data\fmea\ppintlsr.sam
ProcessFunction /Reqs.
Potential FailureMode
Potential Effect(s) ofFailure
Sev
Class
Potential Cause(s) /Mechanismsof Failure
OCCUR
Current Process Controls DETECT
RPN
Recommended Action Responsibility andtarget complete date
ActionTaken
Sev
Occ
Detect
RPN
Laser WeldPressure Plateto Interrupter
Partial failure toweldDetected prior toshipment
scrap 8 Poor placement ofcomponents in tooling
4 Vision systemPull TestOperator Inspection
4 128
Contamination onparts
3 Incoming InspectionOperator Inspection
5 120
Parts not sitting flat 3 Height CheckOperator Inspection
5 120
Machine set up wrong 2 Operator InspectionPull Test
4 64
Non conformingcomponents
4 Incoming Inspection 2 64
Damage on surface ofparts
3 Operator InspectionIncoming Inspection
5 120
Partial failure toweld-Undetectedprior to shipment
Cell failure in field 8 Incorrect settings 2 Operator ChecksPull test
8 128
non conforming parts 3 Incoming Inspection 4 120Contaminated parts 3 Incoming Inspection 8 192Damaged parts 4 Visual Inspection
Incoming Inspection8 256
Non conformingcomponents
4 Incoming Inspection 2 64
Poor placement ofcomponents in tooling
4 Pull testVision System
4 128
Example FMEA cont’d
Severity Pareto
0
5
10
15
Failure Mode
Sco
re
Score 10 8 8 8
Burn ThroughPartial Fail to Weld -
UndetectedPartial Fail to Weld -
DetectedFails to Weld
Pareto by Severity
Severity * Occurrence
28
30
32
34
Failure Mode
Sco
re
Score 30 32 32 32
Burn Through Partial Fail to Weld - Partial Fail to Weld - Fails to Weld
Pareto by Severity x Occurrence
Pareto by Risk Priority Number
0
100
200
300
Failure Mode
Sc
ore
Score 120 256 128 32
Burn Through P artial Fail to Weld - P artial Fail to Weld - Fails to Weld
Pareto by Risk Priority Number(Severity x Occurrence x Detection)
Pareto of Partial Fail to Weld Causes by RPN
0
50
100
150
200
250
300
Causes
Sco
re
Score 256 192 128 128 64
Damaged PartsContaminated
PartsIncorrect Settings
Poor Part Location in
Non Conforming Parts
Pareto of Top Failure Mode
FMEA Summary
Identify PotentialFailure Mode
Actions leadingto ContinuousImprovement
DetermineSeverity
Effect
Determine Occurrence
Cause
IdentifyCurrent Controls
DetermineDetectability
Calculate RiskPriority Number
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