Fmea

Failure Mode Effects Analysis(FMEA)

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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.

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Guided by Customer Requirements Customers are internal Customers are external

Focus is on risk reduction with Design Manufacturing

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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.

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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.

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FMEA Process

Team Selection

CalculateRisk Numbers

Define Process

DetailFailure Mode

CausesEffects

BuildPareto Chart

DevelopRecommended

Actions

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FMEA Process

Team Selection


Define Process

DetailFailure Mode

CausesEffects

BuildPareto Chart

DevelopRecommended

Actions

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FMEA Process

Team Selection

Cross Functional and Multilevel Operators, Mechanics, Engineers, Leaders Team Leader Designated Must be Empowered to implement actions

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FMEA Process

Team Selection


Define Process

DetailFailure Mode

CausesEffects

BuildPareto Chart

DevelopRecommended

Actions

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FMEA Process

Define Process

Develop a Process Flow diagram that is representative of the process as it truly is.

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FMEA Process

Team Selection


Define Process

DetailFailure Mode

CausesEffects

BuildPareto Chart

DevelopRecommended

Actions

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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. Detemine how often failure modes occur. Determine current controls ability to detect.

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FMEA Process

Team Selection


Define Process

DetailFailure Mode

CausesEffects

BuildPareto Chart

DevelopRecommended

Actions

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FMEA Process


Calculate Risk Priority Number (RPN) for each failure mode.

RPN = Worst severity x most frequent occurrence x worst ability to detect.

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FMEA Process

Team Selection


Define Process

DetailFailure Mode

CausesEffects

BuildPareto Chart

DevelopRecommended

Actions

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FMEA Process

BuildPareto Chart

Build Pareto’s One for Severity One for Severity x Occurrence One for RPN

Identify “Vital Few” Failure Modes

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FMEA Process

Team Selection


Define Process

DetailFailure Mode

CausesEffects

BuildPareto Chart

DevelopRecommended

Actions

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FMEA Process

DevelopRecommended

Actions

Develop and implement actions on “Vital Few” Failure Modes

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FMEA Process

Team Selection


Define Process

DetailFailure Mode

CausesEffects

BuildPareto Chart

DevelopRecommended

Actions

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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.


DetailFailure Mode

CausesEffects

BuildPareto Chart

DevelopRecommended

Actions

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FMEA Format

Process Function

Potential Failure Mode

Potential Effect(s) of

Failure

Sev

Class

Potential cause(s) of

Failure

Occ

Current Controls

Prevention

Current control detectio

n

Det

RPN

Recommended Action(s)

Area/Individual Responsible & Completion

Date

Actions Taken sev

occ

det

RPN

Item Process Responsibility Page 1 of 1 Model / year / vehicle FMEA Kay Date Prepared by Core team FMEA Number FMEA Date (Orig.) (Rev.)

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Severity Rating

Severity

Severity is a rating corresponding to the seriousness of an effect of a potential failure mode.

No Effect 1 No Visible effect Very Slight Effect 2 Customer will probably not notice the failure. Slight Effect 3 Slight effect on output performance. Customer slightly annoyed. Minor Effect 4 Minor effect on output or process performance. Slight deterioration. Moderate Effect 5 Moderate effect on performance. Customer dissatisfied. Significant Effect 6 Performance degraded but safe. Discomfort. Repair required. 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.

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Occurrence

Occurrence is a rating corresponding to the rate at which a failure mode occurs before any detecting measures are applied. Occurrence Rating Cpk Failure Rate Notes Almost Impossible

1 Cpk 1.67 5.0 <0.01 per 1000

Failure unlikely. Similar processes or products show no failure.

Remote 2 Cpk 1.50 4.5 0.1 per 1000 Remote number of failures likely. Very Slight 3 Cpk 1.33 4.0 0.5 per 1000 Very few failures likely. Slight 4 Cpk 1.17 3.5 1 per 1000 Few failures likely. Low 5 Cpk 1.00 3.0 2 per 1000 Occasional failure. Medium 6 Cpk 0.83 2.5 5 per 1000 Moderate number of failures likely. Moderately High

7 Cpk 0.67 2.0 10 per 1000 Frequent failures likely.

High 8 Cpk 0.51 1.5 20 per 1000 High number of failures likely. Very High 9 Cpk 0.33 1.0 50 per 1000 Very high number of failures likely. Almost Certain

10 Cpk0.33 1.0

> 100 per 1000

Failures almost certain to occur. Similar processes/products show failures.

Occurrence Rating

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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

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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

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Severity * Occurrence

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30

32

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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

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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)

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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

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FMEA Summary

Identify PotentialFailure Mode

Actions leadingto ContinuousImprovement

DetermineSeverity

Effect

Determine Occurrence

Cause

IdentifyCurrent Controls

DetermineDetectability

Calculate RiskPriority Number

Documents

Fmea