FMEA

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Failure Modes and Effects AnalysisFailure Modes and Effects Analysis(FMEA)(FMEA)

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OutlineOutline What is FMEA?What is FMEA? History History BenefitsBenefits ApplicationsApplications ProcedureProcedure ExerciseExercise SummarySummary


What is FMEA?What is FMEA?

FMEA is an acronym that stands for Failure Modes and Effects FMEA is an acronym that stands for Failure Modes and Effects AnalysisAnalysis

Methodology of FMEA:Methodology of FMEA: Identify the potential failure of a system and its effectsIdentify the potential failure of a system and its effects Assess the failures to determine actions that would eliminate Assess the failures to determine actions that would eliminate

the chance of occurrencethe chance of occurrence Document the potential failuresDocument the potential failures


Failure is ALWAYS a Design Failure is ALWAYS a Design Requirement/CriteriaRequirement/Criteria

All Products fail!All Products fail!

Determining Determining howhow they fail, they fail, whenwhen they will fail, and they will fail, and whywhy they they are failing will allow a designer to incorporate failure as an are failing will allow a designer to incorporate failure as an acceptable design constraint. acceptable design constraint.

Failure as an acceptable design constraint = Customer Failure as an acceptable design constraint = Customer Satisfaction = Design QualitySatisfaction = Design Quality


History of FMEAHistory of FMEA

Created by the aerospace industry in the 1960s.Created by the aerospace industry in the 1960s. Ford began using FMEA in 1972.Ford began using FMEA in 1972. Incorporated by the “Big Three” in 1988.Incorporated by the “Big Three” in 1988. Automotive Industry Action Group and American Society for Automotive Industry Action Group and American Society for

Quality Control copyright standards in 1993.Quality Control copyright standards in 1993.


From: “Inviting Disaster – Lessons From the Edge of Technology”By James R. Chiles

Regarding the continuing failure of rear cargo door on a DC-10:

“ The design was originally going to use hydraulics, but underpressure from its client, American Airlines, to simplify and lighten the DC-10 equipment; McDonnell Douglas shifted to an electric door closer instead. This worried engineers working for the builder of the door assembly, Convair Division of General Dynamics. Convair engineers even sent McDonnell Douglas a formal document, called a “failure modes effects analysis,” describing the problem and the disastrous consequences.


What are the Benefits?What are the Benefits?

Improvements in:Improvements in: SafetySafety QualityQuality ReliabilityReliability


Benefits cont.Benefits cont.

What other potential benefits can be identified?What other potential benefits can be identified? Company imageCompany image User satisfactionUser satisfaction Lower development costsLower development costs Presence of a historical recordPresence of a historical record


ApplicationsApplications

ConceptConcept DesignDesign ProcessProcess ServiceService EquipmentEquipment


FMEA ProcedureFMEA Procedure

Assign a label to each system componentAssign a label to each system component Describe the functions of each partDescribe the functions of each part Identify potential failures for each functionIdentify potential failures for each function


When the Design Fail?When the Design Fail?

Design failure is acceptable if customers perceive it as Design failure is acceptable if customers perceive it as acceptableacceptable.. Design Failure has a direct effect on Customer Design Failure has a direct effect on Customer perceptions of Product Quality.perceptions of Product Quality.

Periodic Maintenance (oil changes)Periodic Maintenance (oil changes) Periodic Replacements (change tires)Periodic Replacements (change tires) Acceptable End of Life (customer expectations – car replacement Acceptable End of Life (customer expectations – car replacement

every 8-10 years)every 8-10 years)


Reliability CurveReliability Curve

Time

Failure Frequency

Chance Infant Mortality

Wear out

Useful Life

Assuming a part/product is designed correctly, statistically it should follow a standard bath-tub curve

Infant Mortality – failures don’t usually affect the customer, except DOAUseful life – failures here are problemsWear Out – failures here are acceptable


Causes of Reliability Curve FailureCauses of Reliability Curve Failure

Early Failure (Infant Mortality)

Chance Failure Wear Out Failure

- Poor Quality Control

- Poor workmanship

- Insufficient Burn In

- Substandard Materials

- Contamination

- Human Error

- Incorrect Packaging

- Design Errors

- Insufficient Safety Margins

- Undetected Defects

- Misapplication

- Abuse of Equipment

- Lack of Preventive Maintenance

- Acts of God

- Stress Concentration

- Corrosion

- Fatigue

- Creep

- Abrasive Wear

- Wrong Environment

- Poor Maintenance


Procedure continuedProcedure continued

Determine the effects of the failuresDetermine the effects of the failures Estimate the severity of the failureEstimate the severity of the failure Estimate the probability of occurrenceEstimate the probability of occurrence


Procedure continuedProcedure continued

Determine the likelihood of detecting the failureDetermine the likelihood of detecting the failure Determine which risks take priorityDetermine which risks take priority Address the highest risksAddress the highest risks

Assign a Risk Priority NumberAssign a Risk Priority Number Update the FMEA as action is takenUpdate the FMEA as action is taken


Design FMEA AnalysisDesign FMEA AnalysisItem and Function

Potential Failure Mode

Potential Effects of

Failure

SEV

Potential Cause(s) of Failure

OCC

Detection Method &

Quality Controls

DET

RPN

Recommended Actions

List Part Name, Number and Function

List the possible modes of failure

List the consequences of failure on part function and on the next higher assembly

List those such as: inadequate design, improper materials, etc.

List these measures available to detect failures before they reach the customer

List them for each of the failure modes identified as being significant by the RPN

= Critical characteristic which may effect safety, compliance with Gov. regulations, or require special controls.

SEV = Severity rating (1 to 10)

OCC = Occurrence frequency (1 to 10)

DET = Detection Rating (1 to 10)

RPN = Risk Priority Number (1 to 1000)


FMEA Flow ChartFMEA Flow Chart

Assign a label to each process or system component

List the function of each component

List potential failure modes

Describe effects of the failures

Determine failure severity

Determine probability of failure

Determine detection rate of failure

Assign RPN

Take action to reduce the highest risk


ExerciseExercise

You are the owner of a lawn mowing service. You are the owner of a lawn mowing service. Use FMEA to analyze the failure modes associated with Use FMEA to analyze the failure modes associated with

mowing a lawn.mowing a lawn.


Exercise cont.Exercise cont.

Brainstorm for possible failures that can occur while Brainstorm for possible failures that can occur while mowing a lawnmowing a lawn

Determine the effects of the failureDetermine the effects of the failure Assign rankings to each failure Assign rankings to each failure Determine the RPNDetermine the RPN



List the current controls over the process of lawn mowingList the current controls over the process of lawn mowing List the recommended actions to reduce severity, List the recommended actions to reduce severity,

detection, and occurrencedetection, and occurrence Assign responsibility and completion dates for each actionAssign responsibility and completion dates for each action



List actions takenList actions taken After actions have been taken, estimate the new rankings After actions have been taken, estimate the new rankings

and calculate the new RPNand calculate the new RPN


SummarySummary

FMEA is a procedure designed to identify and prevent FMEA is a procedure designed to identify and prevent potential failurespotential failures

Provides cost savings and quality enhancing benefitsProvides cost savings and quality enhancing benefits Should be used for all business aspects in both Should be used for all business aspects in both

manufacturing and servicesmanufacturing and services

FMEA

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