Failure Mode and Effect Analysis

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Failure Mode and Effect Failure Mode and Effect AnalysisAnalysis

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Learning ObjectivesLearning Objectives

Provide familiarization with FMEA principles and techniques.

Summarize the concepts, definitions, application options and relationships with other tools.

Learn how to integrate FMEA into your Company SOPs

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Definition of FMEADefinition of FMEA

1. recognize and evaluate the potential failure modes and causes associated with the designing and manufacturing of a new product or a change to an existing product,

2. identify actions which could eliminate or reduce the chance of the potential failure occurring,

3. document the process.

FMEA is a systematic design evaluation procedure

whose purpose is to:

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FMEA is Function-drivenFMEA is Function-drivenFMEA begins with a definition of the FUNCTIONS an item is supposed to perform. The inputs must come from several sources to be effective:

ManufacturingEngineer

SupplierQuality Reliability

EngineerDesign

Engineer

ProgramManagement

Production

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BackgroundBackgroundDeveloped in early 60’s by NASA to “fail-proof” Apollo missions.

Adopted in early 70’s by US Navy .

By late 80’s, automotive industry had implemented FMEA and began requiring suppliers do the same. Liability costs were the main driving force.

Used sporadically throughout industry during 1980’s.

Adopted by Seagate in 1996. Initial application in design centers. Now it’s time to apply FMEA to process applications in Seagate. Six Sigma is the catalyst.

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NASA used FMEA to identify Single Point Failures on Apollo project (SPF = no redundancy & loss of mission). How many did they find?

420and we thought we had No problems!

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Types of FMEA’sTypes of FMEA’s

SYSTEM

DESIGN

PROCESS

System FMEA is used to analyze systems and subsystems in the early concept and design stages.

System FMEA is used to analyze systems and subsystems in the early concept and design stages.

Design FMEA is used to analyze products before they are released to production

Design FMEA is used to analyze products before they are released to production

Process FMEA is used to analyze manufacturing, assembly and administrative processes

Process FMEA is used to analyze manufacturing, assembly and administrative processes

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When Is the FMEA Started?When Is the FMEA Started?

Do the best you can with what you have.

AS EARLY AS POSSIBLEGuideline:

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When to StartWhen to Start When new systems, products and

processes are being designed When existing designs and

processes are being changed When carry-over designs or

processes will be used in new applications or environments

After completing a Problem Solving Study, to prevent recurrence of a problem

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Process FMEA FormProcess FMEA FormPRODUCT: FMEA NO.

PROCESS FMEA PROCESS/OPERATION: PAGE OF

PLANNING REFERENCE: DATE: BY:

Oklahoma City

PROCESS DESCRIPTION POTENTIAL POTENTIAL S POTENTIAL O CURRENT D RPN ACTION CORRECTIVE RESPONSIBILITY ACTION RESULTINGFAILURE MODE EFFECTS OF CAUSE(S) OF CONTROLS PRIORITY ACTION & DATE DUE TAKEN

FUNCTION FAILURE FAILURE S O D RPN

DETECTIONOCCURRENCESEVERITY RPN = S x O x D

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Process Failure ModeProcess Failure Mode The potential failure mode is the manner in which the

process could fail to perform its intended function. The failure mode for a particular operation could be a

cause in a subsequent (downstream) operation or an effect in associated with a potential failure in a previous (upstream) operation.

FAILUREMODE

EFFECT

PREVIOUSOPERATION

CAUSE

NEXTOPERATION

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Process CausesProcess Causes

Process FMEA considers process variability due to:

OPERATOR SET-UP MACHINE

METHOD ENVIRONMENT MEASUREMENT

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Current ControlsCurrent Controls Assessment of the ability of the control to

detect the failure before the item leaves the manufacturing area and ships to the customer.

Capability of all controls in the process to prevent escapes

SPC

Process Capability

Gage R&R

Sampling

Testing

DoE

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Typically, three items are scored:

Types of MeasuresTypes of Measures

SEVERITYAs it applies to the effects on the local system, next level, and end user

OCCURRENCELikelihood that a specific cause will occur and result in a specific failure mode

DETECTIONAbility of the current / proposed control mechanism to detect and identify the failure mode

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SeveritySeverityEffect Criteria: Severity of Effect Defined Ranking

Hazardous: Without Warning

May endanger operator. Failure mode affects safe vehicle operation and / or involves noncompliance with government regulation. Failure will occur WITHOUT warning.

10

Hazardous: With Warning

May endanger operator. Failure mode affects safe vehicle operation and / or involves noncompliance with government regulation. Failure will occur WITH warning.

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Very HighMajor disruption to production line. 100% of product may have to be scrapped. Vehicle / item inoperable, loss of primary function. Customer very dissatisfied.

8

HighMinor disruption to production line. Product may have to be sorted and a portion (less than 100%) scrapped. Vehicle operable, but at a reduced level of performance. Customer dissatisfied.

7

ModerateMinor disruption to production line. A portion (less than 100%) may have to be scrapped (no sorting). Vehicle / item operable, but some comfort / convenience item(s) inoperable. Customers experience discomfort.

6

LowMinor disruption to production line. 100% of product may have to be reworked. Vehicle / item operable, but some comfort / convenience item(s) operable at reduced level of performance. Customer experiences some dissatisfaction.

5

Very LowMinor disruption to production line. The product may have to be sorted and a portion (less than 100%) reworked. Fit / finish / squeak / rattle item does not conform. Defect noticed by most customers.

4

MinorMinor disruption to production line. A portion (less than 100%) of the product may have to be reworked on-line but out-of-station. Fit / finish / squeak / rattle item does not conform. Defect noticed by average customers.

3

Very MinorMinor disruption to production line. A portion (less than 100%) of the product may have to be reworked on-line but in-station. Fit / finish / squeak / rattle item does not conform. Defect noticed by discriminating customers.

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None No effect. 1

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OccurrenceOccurrenceProbability of Failure Possible Failure Rates Cpk Ranking

Very High: 1 in 2 < 0.33 10

Failure is almost inevitable 1 in 3 0.33 9

High: Generally associated with processes similar to previous

1 in 8 0.51 8

processes that have often failed 1 in 20 0.67 7

Moderate: Generally associated with processes similar to

1 in 80 0.83 6

previous processes which have 1 in 400 1.00 5

experienced occasional failures, but not in major proportions

1 in 2,000 1.17 4

Low: Isolated failures associated with similar processes

1 in 15,000 1.33 3

Very Low: Only isolated failures associated with almost identical processes

1 in 150,000 1.5 2

Remote: Failure is unlikely. No failures ever associated with almost identical processes

1 in 1,500,000 1.67 1

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This is best thought of as Escape Potential - the higher thescore, the greater the problem

Detection (“Escape”)Detection (“Escape”)

Detection Criteria: Liklihood the existence of a defect will be detected by test content before product advances to

next or subsequent process

Ranking

Almost Impossible Test content detects < 80 % of failures 10

Very Remote Test content must detect 80 % of failures 9

Remote Test content must detect 82.5 % of failures 8

Very Low Test content must detect 85 % of failures 7

Low Test content must detect 87.5 % of failures 6

Moderate Test content must detect 90 % of failures 5

Moderately High Test content must detect 92.5 % of failures 4

High Test content must detect 95 % of failures 3

Very High Test content must detect 97.5 % of failures 2

Almost Certain Test content must detect 99.5 % of failures 1

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Risk Priority NumberRisk Priority Number

RPN = O x S x DOccurrence x Severity x Detection

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Basic StepsBasic Steps1. Develop a Strategy

– Form a FMEA teamST91260A

DRIVE

BASE SUB

SYSTEM & FIRMWARE

COVERMEDIA

DISC PACK

FINAL ARM

ARM SUB

ARM COIL

BOBBIN

ROT. ARM

SP. FLEX SPINDLE

STATOR

ROTOR

HDA ASSEMBLY

BASE DECK

RECIR FILTER

BREATH. FILTER

LABELS

PCB ASSEMBLY

DISC CLAMP

BAL. WT

SPACERS

MAG ASSY LATCH

ARM SUB

ARM SUB

BASE DECK

DAMPER

SEAL

MOTOR POLES, POLE SPACER

Teams will be established to evaluate the application of FMEA in areas shown by the shading on the following diagram. Each "FMEA" Team under the direction of the FMEA Facilitator will:- ESTABLISH a strategy focusing on new technology, past issues, new or redesigned components, both from the product (design) and process perspectives..- PREPARE a Design and a Process FMEA for the selected components or subassemblies..- DETERMINE functions, potential failure modes, effects, causes, and verification activities planned or in-place.. - RECOMMEND corrective actions to the product team..

FIRST PRIORITY

SECOND PRIORITY

THIRD PRIORITY

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1. Develop a Strategy

2. Review the design/process– Develop process map and

identify all process steps

Basic StepsBasic Steps

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Basic StepsBasic Steps1. Develop a Strategy2. Review the design /process

3. List functions– List all the value-added

process– For each process step,

list process inputs (process characteristics

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2. Review the design /process

3. List functions

4. Brainstorm potential failure modes


EFFECTCAUSES

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3. List functions


5. List the potential consequences of each failure mode


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3. List functions


5. List the potential consequences of each failure mode

6. Assign severity (SEV) scorePRODUCT: FMEA NO.

PROCESS/OPERATION: PAGE OF

DESIGN (OR PROCESS) FMEAPLANNING REFERENCE: DATE: BY:

Oklahoma CityPOTENTIAL POTENTIAL S POTENTIAL O CURRENT D RPN ACTION CORRECTIVE RESPONSIBILITY ACTION RESULTING

FUNCTION FAILURE MODE EFFECTS OF CAUSE(S) OF CONTROLS PRIORITY ACTION & DATE DUE TAKENFAILURE FAILURE S O D RPN

DETECTIONOCCURRENCESEVERITY RPN = S x O x D


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1. Develop a Strategy2. Review the design /process3. List functions4. Brainstorm potential failure modes5. List the potential consequences of each failure

mode6. Assign severity (SEV) score

7. Identify the cause(s) of each failure mode.


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1. Develop a Strategy2. Review the design /process3. List functions4. Brainstorm potential failure modes5. List the potential consequences (effect) of each

failure mode6. Assign severity (SEV) score7. Identify the cause(s) of each failure mode.

8. Assign occurrence (OCC) scores.


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1. Develop a Strategy2. Review the design /process3. List functions4. Brainstorm potential failure modes5. List the potential consequences (effect) of each failure

mode6. Assign severity (SEV) score7. Identify the potential cause(s) of each failure mode.8. Assign occurrence (OCC) scores.

9. Identify current controls to detect the failure modes.


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Basic StepsBasic Steps1. Develop a Strategy2. Review the design /process3. List functions4. Brainstorm potential failure modes5. List the potential consequences (effect) of each failure mode6. Assign severity (SEV) score7. Identify the potential cause(s) of each failure mode.8. Assign occurrence (OCC) scores.9. Identify current controls to detect the failure modes.

10. Assign an escaped detection (DET) score for each cause and control.

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Basic StepsBasic Steps1. Develop a Strategy2. Review the design /process3. List functions4. Brainstorm potential failure modes5. List the potential consequences (effect) of each failure mode6. Assign severity (SEV) score7. Identify the potential cause(s) of each failure mode.8. Assign occurrence (OCC) scores.9. Identify current controls to detect the failure modes.10. Assign an escaped detection (DET) score for each cause and

control.

11. Calculate the Risk Priority Numer (RPN) for each line in the FMEA.

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1. Develop a Strategy2. Review the design /process3. List functions4. Brainstorm potential failure modes5. List the potential consequences (effect) of each failure mode6. Assign severity (SEV) score7. Identify the potential cause(s) of each failure mode.8. Assign occurrence (OCC) scores.9. Identify current controls to detect the failure modes.10. Assign an escaped detection (DET) score for each cause and

control.11. Calculate the Risk Priority Numer (RPN) for each line in the FMEA.

12. Determine the action to be taken.


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1. Develop a Strategy2. Review the design /process3. List functions4. Brainstorm potential failure modes5. List the potential consequences (effect) of each failure mode6. Assign severity (SEV) score7. Identify the potential cause(s) of each failure mode.8. Assign occurrence (OCC) scores.9. Identify current controls to detect the failure modes.10. Assign an escaped detection (DET) score for each cause and control.11. Calculate the Risk Priority Numer (RPN) for each line in the FMEA.12. Determine the action to be taken.

13. Recalculate the RPNs based on the actions plans.


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Shortcomings of RPNShortcomings of RPN

A 8 4 3 96

B 4 8 3 96

SAME RESULT

Failu

re M

ode

Seve

rity

Occ

urre

nce

Effect

iven

ess

RPN

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Action PriorityAction Priority

PRIORITY RPN RANGE

A Over 200

BCD

100-199

26-99

1-25

BUMP HEAD

WALK INTO DOOR

PAINCAN’T SEE

GET GLASSES WEAR HELMET

REMOVE DOORS

LIKELY

CAUSE

POTENTIAL

PROBLEM

LIKELY

EFFECT

ACTIONSPREVENTIVECONTINGENT

- ADAPTIVE

-CORRECTIVE

TRIGGER

INITIAL PROBLEM

BUMP HEAD

WALK INTO DOOR

PAINCAN’T SEE

GET GLASSES WEAR HELMET

REMOVE DOORS

LIKELY

CAUSE

POTENTIAL

PROBLEM

LIKELY

EFFECT


- ADAPTIVE

-CORRECTIVE

TRIGGER

1st WHYCAUSE BECOMES

NEW PROBLEM

PROBLEM

BECOMES EFFECT

BUMP HEAD

WALK INTO DOOR AND

PAIN

CAN’T SEE

SURGERY

LIKELY

CAUSE

POTENTIAL

PROBLEM

LIKELY

EFFECT


- ADAPTIVE

-CORRECTIVE

TRIGGER

1st WHY

GET GLASSES

NEARSIGHTED

BUMP HEAD

WALK INTO DOOR AND

PAIN

CAN’T SEE

SURGERY

LIKELY

CAUSE

POTENTIAL

PROBLEM

LIKELY

EFFECT


- ADAPTIVE

-CORRECTIVE

TRIGGER

2ND WHY

GET GLASSES

NEARSIGHTED

BUMP HEAD

WALK INTO DOOR AND

PAIN

CAN’T SEE

SURGERY

LIKELY

CAUSE

POTENTIAL

PROBLEM

LIKELY

EFFECT


- ADAPTIVE

-CORRECTIVE

TRIGGER

2ND WHYNEARSIGHTED

CUT OUTSTAR TREK

TOO MUCH T.V.

HAVE WE FOUND ROOT CAUSE?

BUMP HEAD

WALK INTO DOOR AND

PAIN

CAN’T SEE

SURGERY

LIKELY

CAUSE

POTENTIAL

PROBLEM

LIKELY

EFFECT


- ADAPTIVE

-CORRECTIVE

TRIGGER

2ND WHYNEARSIGHTED

CUT OUTSTAR TREK

TOO MUCH T.V.

OR GONE TOO FAR !

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Determining Level of Determining Level of AnalysisAnalysis

PRODUCT: SEAGATE DRIVE STXXXXXSUBSYSTEMS SPINDLE MOTOR

DESIGN FMEADRAWING OR SPEC REFERENCE:

Oklahoma CityPROCESS DESCRIPTION POTENTIAL POTENTIAL S POTENTIAL O CURRENT E RPN

FAILURE MODE EFFECTS OF CAUSE(S) OF CONTROLS

FUNCTION FAILURE FAILURE

SPINDLE ROTATES MEDIA AT FIXED RPM

NO SPIN, OR DRIVE RUNS IN REVERSE

DRIVE INOPERABLE FAILURE OF FLEX SOLDER JOINT DUE TO INSUFFICIENT STRAIN RELIEF

RESISTANCE MEASUREMENT AT INCOMING INSPECTION

EFFECTIVENESSOCCURRENCESEVERITY

Handbook pg. 43Here’s a Seagate Example

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Handbook pg. 43

Cause becomes Failure Mode


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Handbook pg. 43

Failure Mode becomes Effect


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PROVIDES A DEEPER LEVEL OF ANALYSIS BY ASKINGYOU FOR THE DESIGN CAUSES AND VERIFICATIONOF INSUFFICIENT STRAIN RELIEF







FAILURE OF FLEX SOLDER JOINT DUE TO INSUFFICIENT STRAIN RELIEF

NO SPIN, OR DRIVE RUNS IN REVERSE CAUSING DRIVE TO BE INOPERABLE


Handbook pg. 43

WHY?


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What’s Wrong With This What’s Wrong With This Picture?Picture?

NUMBER OF PROCESS FAILURE CAUSES

POWER

GAGE

DESIGN

HANDLING

SET-UP

CONTAMINATION

TOOLING

OPERATOR ERROR

0 5 10 15 20 25 30 35 40 45 50

POWER

GAGE

DESIGN

HANDLING

SET-UP

CONTAMINATION

TOOLING

OPERATOR ERROR

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ActionsActions

The design or process must be improved based on the results of the FMEA study.

A well-developed FMEA will be of limited value without positive and effective corrective actions.

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Elements of FMEAElements of FMEAFailure Mode Any way in which a process could could fail to meet some measurable

expectation.

Effect Assuming a failure does occur, describe the effects. List separately each main effect on both a downstream operation and the end user.

Severity Using a scale provided, rate the seriousness of the effect. 10 represents worst case, 1 represents least severe.

Causes This is the list of causes and/or potential causes of the failure mode.

Occurrence This is a ranking, on a scale provided, of the likelihood of the failure occurring. 10 represents near certainty; 1 represents 6 sigma. In the case of a Six Sigma project, occurrence is generally derived from defect data.

Current Controls All means of detecting the failure before product reaches the end user are listed under current controls.

Effectiveness The effectiveness of each current control method is rated on a provided scale from 1 to 10. A 10 implies the control will not detect the presence of a failure; a 1 suggests detection is nearly certain.

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It is conducted on a timely basisand

It is applied by a product teamand

Its results are documented

FMEA is most effective when FMEA is most effective when

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Example of how FMEA can be used in SCAR.

5.2.1.2 Quality Manager or his designate shall discuss with Customer for re-inspection of finished product in the inventory. Only when the non-conformance is detected, a materialpurge shall be initiated. If Customer does not agree, then a material purge will be initiated.

5.2.1.3 The designated Quality Engineer shall reply in writing or by phone to the Customer within 24 hours on the immediate containment plan implemented upon receiving the C.A.R orcomplaint.

5.2.1.4 The concerned Departmental Manager or his designate or Supplier shall head and formthe investigation team. The team shall consists of the following :a) Chairman - Responsible Departmental Manager or his appointed designate.b) Members - Quality Manager / QA Engineer

- Production / Manufacturing Engineer- Material Manager (if applicable)

5.2.1.5 The assigned Engineer from Production / Engineering will investigate, identifyand analyze the possible cause.

5.2.1.6 He/She will use any of the tools (e.g.7QC Tools, PSDM & DOE, etc.) to solve the problem.

FOR REFERENCE

Section of SCAR procedure

FMEA can be used to identify the potential cause of failure and determine whether the current control is sufficient.

Integrating FMEA into SOPsIntegrating FMEA into SOPs

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S/N Tasks Task Owner Target Completion Date

Specific Training needed for Task

Owner/ Date

Core Team Member In

Charge

Internal Verified Date

Group Phase End Date

Group 1 Tools

1 SCAR

Integrate FMEA into SCAR procedure/system

Mike 10-Dec-01 FMEA -15 Nov-01

Nick 15-Dec-01 31-Dec-01

Link Tools Integration Tasks to Work Link Tools Integration Tasks to Work Breakdown StructureBreakdown Structure

The effort to integrate FMEA into SCAR procedures should be translated into specific tasks in the Work Breakdown Structure.

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End of TopicEnd of Topic

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Failure Mode and Effect Analysis

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