© ABSL Power Solutions 2007 © STM Quality Limited STM Quality Limited Failure Mode and Effect Analysis TOTAL QUALITY MANAGEMENT F.M.E.A

© ABSL Power Solutions 2007© STM Quality Limited

STM Quality Limited

Failure Mode and Effect Analysis

TOTAL QUALITY MANAGEMENT

F.M.E.A.

© STM Quality Limited

STM Quality Limited

What is an F.M.E.A.?

Why do we need it?

When do we do it?

What do we do when it’s finished?

Introduction


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What is aFailure Mode and Effect

Analysis?

F.M.E.A. is a simple way of predicting what might go wrong.

By using a structured method, results can be quantified and hence compared.


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How Does It Work?

Identifies critical and significant characteristics

Helps engineers prioritise and focus on eliminating product and process concerns and help prevent problems from occurring.


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Purpose

Utilise individuals’ knowledge and skills within a team environment

Identify potential failures at the earliest possible stage of new design/process


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F.M.E.A.s can be done for any design, manufacturing or in-service activity

F.M.E.A.s are modular and can be carried out for single parts or large assemblies


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F.M.E.A. - Types

Component

DesignFMEA

DesignFMEA

System

Sub-System

ProcessFMEA

ProcessFMEA

Assembly

Manufacturing

System

Component

Sub-System

System

Component

Sub-System


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Benefits – Design F.M.E. A.

Aids in evaluating requirements and alternatives

Aids in initial Design for ManufactureIncreases probability of detecting

failure modes and their effectsProvides additional information for

testing requirementsHelps identify critical and significant

characteristicsHelps validate test methods


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Benefits – Process F.M.E. A.

Identifies potential process related failure modes which will effect internal/external customers

Reduces costs of repairs due to faulty process methodology

Increases efficiencyEstablishes a priority system for

considering corrective actionsIdentifies confirmed critical and

significant characteristics


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F.M.E. A. and Control Plans

F.M.E.A Identifies Risks

How Risks are ControlledControl Plan


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F.M.E.A. Model

___ System

___ Subsystem

___ Component

Model Year / Vehicle(s):

Core Team:

PotentialFailure Mode and Effects Analysis

Design Responsibility:

Key Date:

FMEA Number:

Page 1 of 1

Prepared by:

FMEA Date ( Orig): (Rev)

Action Results

Potential

Failure

Mode

Potential

Effect(s)

of Failure

S

e

v

C

l

a

s

s

Potential

Cause(s)/

Mechanisms

Failure

O

c

c

u

r

Current

Design

Controls

D

e

t

e

c

R

P

N

Recommended

Action(s)

Responsibility &

Target

Completion Date

Actions

Taken

Se

v

Oc

c

De

t

RP

N

Item

Function


STM Quality Limited

To meet Customer Requirements – A.P.Q.P.

To keep up with competition

To retain current business

Help obtain new business

Why Do A Failure Mode and Effect

Analysis?


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Generating F.M.E.A.s

Failure Mode and

Effects Analysis

Failure Mode and

Effects Analysis

Who initiates?Who initiates?

Who prepares?Who prepares?

Who updates?Who updates?

Who is FMEA customer?

Who is FMEA customer?

How is FMEA documented?

How is FMEA documented?

When started and updated?

When started and updated?

When is FMEA complete?

When is FMEA complete?

When to discard?

When to discard?


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FM.E.A.s are living documents and are updated when:

Modification to a component, process or system is planned;

Component is to be used in new environment;

Customer concern arises.

Managing F.M.E.A.s


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Process F.M.E.A.s


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Firstly, create a flow chart of operationsThen identify boundary for analysisNext, create a flow chart for one

operation

Process Flow Chart


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Transportraw

materials

Process Flow Chart of Operations

Op.10 Preparation Op.30 Weld

Op.40 assemble

Op.50 Trim to size

Op.60 Inspect & Pack

Store/Pack

Op.20 Mould

Boundary for analysis


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Place part on trim machine fixture

Boundary For Analysis

Press ‘Start’ button

Op.50.1

Remove from fixture when cycle complete

Op.50 Trim

Op.50.2

Op.50.3


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Process/Function Requirements

___ System

___ Subsystem

___ Component


Core Team:



Key Date:

FMEA Number:

Page 1 of 1

Prepared by:


Action Results

Potential

Failure

Mode

Potential

Effect(s)

of Failure

S

e

v

C

l

a

s

s

Potential

Cause(s)/

Mechanisms

Failure

O

c

c

u

r

Current

Design

Controls

D

e

t

e

c

R

P

N

Recommended

Action(s)

Responsibility &

Target

Completion Date

Actions

Taken

Se

v

Oc

c

De

t

RP

N

Item

Function


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From Process flow:

Enter a simple description of the process being analysed i.e. Place part on trim machine fixture;

Indicate the purpose of the process being analysed i.e. Fully seat part in correct orientation;

List separately other operations involved with that process;

Process function contains both product and process characteristics.

Process/Function Requirements


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What does the process do at this operation?

What is the process purpose?

What is its function?

Define the Process Purpose


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Place part on trim machine fixture

Process Purpose

Press ‘Start’ button

Op.50.1

Remove from fixture when cycle complete

Op.50 Trim

Op.50.2

Op.50.3

• Locate part on fixture - correct orientation - fully seated

• Start trimming programme

• Position in checking fixture - fully seated

• Remove waste before packing


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Determine What Can Go Wrong

___ System

___ Subsystem

___ Component


Core Team:



Key Date:

FMEA Number:

Page 1 of 1

Prepared by:


Action Results

Potential

Failure

Mode

Potential

Effect(s)

of Failure

S

e

v

C

l

a

s

s

Potential

Cause(s)/

Mechanisms

Failure

O

c

c

u

r

Current

Design

Controls

D

e

t

e

c

R

P

N

Recommended

Action(s)

Responsibility &

Target

Completion Date

Actions

Taken

Se

v

Oc

c

De

t

RP

N

Item

Function


STM Quality Limited

Definition:

Potential failure mode is the manner in which the process could potentially fail to meet the process requirements and/or design intent.

It is a description of the non-conformance at that specific operation.

Failure Mode


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Examine process flow using:

No functionPartial functionIntermittent function

Failure Mode


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Effects Of Failure Mode

___ System

___ Subsystem

___ Component


Core Team:



Key Date:

FMEA Number:

Page 1 of 1

Prepared by:


Action Results

Potential

Failure

Mode

Potential

Effect(s)

of Failure

S

e

v

C

l

a

s

s

Potential

Cause(s)/

Mechanisms

Failure

O

c

c

u

r

Current

Design

Controls

D

e

t

e

c

R

P

N

Recommended

Action(s)

Responsibility &

Target

Completion Date

Actions

Taken

Se

v

Oc

c

De

t

RP

N

Item

Function


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Definition:

The effects of the failure mode on the customer. The customer could be the next operation, subsequent operations or the final customer / user.

Effects of Failure Mode


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Identify potential effects on:next userdownstream userultimate customervehicle operationoperator safetyCompliance with government

regulationsmachines / equipment

Effects of Failure Mode


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Effects of Failure

Failure

mode

Nextuser

Downstream

users

Ultimatecustome

r

Vehicleoperatio

n

Operatorsafety

Governmentregulations


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Effects of Failure

Failure

mode

Nextuser

Downstream

users

Ultimatecustome

r

Vehicleoperatio

n

Operatorsafety

Governmentregulations

Failure mode: Incorrect Trim Programme

Incorrect to checking

fixture

Packaged in wrong stillage

Cannot fit to

vehicle.Stop

Production line

Cannot fit to

vehicleNone None


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Severity

___ System

___ Subsystem

___ Component


Core Team:



Key Date:

FMEA Number:

Page 1 of 1

Prepared by:


Action Results

Potential

Failure

Mode

Potential

Effect(s)

of Failure

S

e

v

C

l

a

s

s

Potential

Cause(s)/

Mechanisms

Failure

O

c

c

u

r

Current

Design

Controls

D

e

t

e

c

R

P

N

Recommended

Action(s)

Responsibility &

Target

Completion Date

Actions

Taken

Se

v

Oc

c

De

t

RP

N

Item

Function


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Definition:

An assessment of the seriousness of the effect of the potential failure mode on the customer.

Severity


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Hazardous without warning

Suggested Severity Scoring

Effect Criteria: Severity of Effect Ranking

10

Hazardous with

warning

9

Low Minor disruption to production line 100% of product may have to be reworked

5

None No Effect 1

May endanger machine or assembly operator…non compliance government regulation without warning

May endanger machine or assembly operator…non compliance government regulation without warning


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Critical or Special Characteristic

___ System

___ Subsystem

___ Component


Core Team:



Key Date:

FMEA Number:

Page 1 of 1

Prepared by:


Action Results

Potential

Failure

Mode

Potential

Effect(s)

of Failure

S

e

v

C

l

a

s

s

Potential

Cause(s)/

Mechanisms

Failure

O

c

c

u

r

Current

Design

Controls

D

e

t

e

c

R

P

N

Recommended

Action(s)

Responsibility &

Target

Completion Date

Actions

Taken

Se

v

Oc

c

De

t

RP

N

Item

Function


STM Quality Limited

Identify Special Characteristics

CRITICAL: Requirements that affect compliance with government regulations or safe vehicle / product function and require special controls (Score = 9 or 10)

SIGNIFICANT: Product and/or test requirements important for customer satisfaction, summarized on Control Plan and require special controls (Score = 5 to 8,)


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Cause

___ System

___ Subsystem

___ Component


Core Team:



Key Date:

FMEA Number:

Page 1 of 1

Prepared by:


Action Results

Potential

Failure

Mode

Potential

Effect(s)

of Failure

S

e

v

C

l

a

s

s

Potential

Cause(s)/

Mechanisms

Failure

O

c

c

u

r

Current

Design

Controls

D

e

t

e

c

R

P

N

Recommended

Action(s)

Responsibility &

Target

Completion Date

Actions

Taken

Se

v

Oc

c

De

t

RP

N

Item

Function


STM Quality Limited

Definition:

Potential cause of a failure is defined as how the failure could occur in terms of something that can be corrected or controlled.

Cause


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Only specific errors or malfunctions (eg. Operator fails to remove waste) should be listed.

Ambiguous phrases (e.g. Operator error, machine malfunction) should not be used.

Cause


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Occurrence

___ System

___ Subsystem

___ Component


Core Team:



Key Date:

FMEA Number:

Page 1 of 1

Prepared by:


Action Results

Potential

Failure

Mode

Potential

Effect(s)

of Failure

S

e

v

C

l

a

s

s

Potential

Cause(s)/

Mechanisms

Failure

O

c

c

u

r

Current

Design

Controls

D

e

t

e

c

R

P

N

Recommended

Action(s)

Responsibility &

Target

Completion Date

Actions

Taken

Se

v

Oc

c

De

t

RP

N

Item

Function


STM Quality LimitedHow frequently the cause is projected to

occur. Based on:

– Historical manufacturing/assembly failure rates with similar parts

– Statistical data from similar process– Existing process controls– Customer concern data– Rejects, PPM, Warranty data

Occurrence


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Very high

Suggested Occurrence Scoring

Probability Possible Failure Rates Ranking

10

Moderate 6

Remote Less than 1 in 500,000 1

About 1 in 2

About 1 in 80

About 1 in 3 9

About 1 in 400 5

About 1 in 2000 4


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Controls

___ System

___ Subsystem

___ Component


Core Team:



Key Date:

FMEA Number:

Page 1 of 1

Prepared by:


Action Results

Potential

Failure

Mode

Potential

Effect(s)

of Failure

S

e

v

C

l

a

s

s

Potential

Cause(s)/

Mechanisms

Failure

O

c

c

u

r

Current

Design

Controls

D

e

t

e

c

R

P

N

Recommended

Action(s)

Responsibility &

Target

Completion Date

Actions

Taken

Se

v

Oc

c

De

t

RP

N

Item

Function


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Increasing inspection is only a temporary measure. Permanent Corrective Action is required.

Emphasis must be placed on preventing defects rather than detecting them (e.g. S.P.C.)

Controls


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In Process Control column on FMEA:Prevention Controls

– Place a ‘P’ before each prevention control listed

Detection Controls– Place a ‘D’ before each detection

control listed

Controls


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Prevention: (Preferred option)

Prevent the cause / mechanism of failure or the failure mode occurring, or reduce their rate of occurrence

Prevention Controls


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Detection:

Detect the cause / mechanism of failure or the failure mode and lead to corrective actions

Detection Controls


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Engineering specification testsPoka-yoke or error proofingAudible or visual warning devicesIn Process / Final inspectionS.P.C.Process / Parameter audits

Process Control Examples


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Detection

___ System

___ Subsystem

___ Component


Core Team:



Key Date:

FMEA Number:

Page 1 of 1

Prepared by:


Action Results

Potential

Failure

Mode

Potential

Effect(s)

of Failure

S

e

v

C

l

a

s

s

Potential

Cause(s)/

Mechanisms

Failure

O

c

c

u

r

Current

Design

Controls

D

e

t

e

c

R

P

N

Recommended

Action(s)

Responsibility &

Target

Completion Date

Actions

Taken

Se

v

Oc

c

De

t

RP

N

Item

Function


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Definition:Detection is an assessment of the probability that:

The process controls listed will detect a potential cause /mechanism (process weakness) , or

The process controls listed will detect a subsequent failure mode.

Detection


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Certain

Suggested Detection Scoring

Detection Likelihood of Detection Ranking

10

Moderate 4

Almost certain Process control will almost certainly detect a potential cause

1

Process control will not and/or cannot detect a potential cause … or there is no process control

Moderately high chance the process control will detect potential cause


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Severity

Select and Manage Actions

To Reduce Consider This Action To Accomplish

Eliminate failure modes

Occurrence Prevent cause(s), or reduce their rate ofoccurrence

Detection Add to or improve the control methods

Change the design ... or the process if operator safety is involved

Change the design or process

Improve ability to detect a failure mode


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Risk Priority Number (R.P.N.)

___ System

___ Subsystem

___ Component


Core Team:



Key Date:

FMEA Number:

Page 1 of 1

Prepared by:


Action Results

Potential

Failure

Mode

Potential

Effect(s)

of Failure

S

e

v

C

l

a

s

s

Potential

Cause(s)/

Mechanisms

Failure

O

c

c

u

r

Current

Design

Controls

D

e

t

e

c

R

P

N

Recommended

Action(s)

Responsibility &

Target

Completion Date

Actions

Taken

Se

v

Oc

c

De

t

RP

N

Item

Function


STM Quality Limited


We have seen that the F.M.E.A. asks three questions:

What might go wrong?What effect would this have?What caused the problem?


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From the answers to the three questions we can work out a risk priority number:

Risk Priority Number


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How do we calculate the R.P.N.?We simply use the scoring criteria

easily remembered by:

Severity of the problem

Occurrence of the problem

Detection of the problem


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Each is given a value from 1 to 10Let’s try this out for S, O & D

For Example,Severity = 1 2 3 4 5 6 7 8 9 10Occurrence = 1 2 3 4 5 6 7 8 9 10Detection = 1 2 3 4 5 6 7 8 9 10Each of these could be assessed in a rating from

1 to 10.


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How can we use these values to give an overall risk?

We multiply the three figures together:e.g. 7 x 4 x 3 = 84. So the R.P.N. is 84.


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From the R.P.N. we can now see the areas of greatest concern

i.e. Those failures with the highest risk priority numbers


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We can now focus our attention on the worst problems – those with the highest R.P.N.

With limited resources, this must be a good idea

We can now eliminate or reduce the potential failure


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Recommended Actions

___ System

___ Subsystem

___ Component


Core Team:



Key Date:

FMEA Number:

Page 1 of 1

Prepared by:


Action Results

Potential

Failure

Mode

Potential

Effect(s)

of Failure

S

e

v

C

l

a

s

s

Potential

Cause(s)/

Mechanisms

Failure

O

c

c

u

r

Current

Design

Controls

D

e

t

e

c

R

P

N

Recommended

Action(s)

Responsibility &

Target

Completion Date

Actions

Taken

Se

v

Oc

c

De

t

RP

N

Item

Function


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Recommended Actions

The intent of any Recommended Action is to reduce rankings in the following order:

SeverityOccurrenceDetection


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Responsibility & Target Date

___ System

___ Subsystem

___ Component


Core Team:



Key Date:

FMEA Number:

Page 1 of 1

Prepared by:


Action Results

Potential

Failure

Mode

Potential

Effect(s)

of Failure

S

e

v

C

l

a

s

s

Potential

Cause(s)/

Mechanisms

Failure

O

c

c

u

r

Current

Design

Controls

D

e

t

e

c

R

P

N

Recommended

Action(s)

Responsibility &

Target

Completion Date

Actions

Taken

Se

v

Oc

c

De

t

RP

N

Item

Function


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Responsibility

Each action must be assigned to a specific individual and not a dept. / organisation

If the individual is not in the team a team member should be assigned responsibility for communication and feedback of action with a target date.


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Actions Taken

___ System

___ Subsystem

___ Component


Core Team:



Key Date:

FMEA Number:

Page 1 of 1

Prepared by:


Action Results

Potential

Failure

Mode

Potential

Effect(s)

of Failure

S

e

v

C

l

a

s

s

Potential

Cause(s)/

Mechanisms

Failure

O

c

c

u

r

Current

Design

Controls

D

e

t

e

c

R

P

N

Recommended

Action(s)

Responsibility &

Target

Completion Date

Actions

Taken

Se

v

Oc

c

De

t

RP

N

Item

Function


STM Quality Limited

Actions Taken

After the corrective action has been identified, estimate and record the resulting severity, occurrence and detection rankings

Calculate and record the resulting R.P.N.P.F.M.E.A. team must review the revised

R.P.N.s to determine if further action is necessary.

If no action write ‘None’.


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Actions Taken

Once the actions have been implemented, the estimated values, ‘the future’, becomes ‘the present’ and can be incorporated into the LHS of the form on the next F.M.E.A.


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Advantages of F.M.E.A.s

Customer confidenceImproved quality & efficiencyImproved participation across

traditional boundaries


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More advantages of F.M.E.A.s

Uses extensive & untapped personnel/process knowledge to improve new & existing work

Provides a vehicle for continuous improvement

Supports product liability


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There are drawbacks for F.M.E.A.s:

Must be adequate time & resources for F.M.E.A.s

Product LiabilityNeed for in-depth product &

process or design knowledge


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Remember - F.M.E.A. is a practical activity and there will be differing interpretations regarding to the failure modes and rankings - this does not matter, provided that the team does not get bogged down in this way!


STM Quality Limited


Keep the meetings short and the tempo sharp!

Design F.M.E.A. team - Chairman, Production, Service, Quality Personnel

Process F.M.E.A. team - YOU CHOOSE!

Documents

© ABSL Power Solutions 2007 © STM Quality Limited STM Quality Limited Failure Mode and Effect Analysis TOTAL QUALITY MANAGEMENT F.M.E.A