fmea presentation

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Failure Mode & Effect Analysis

© 2006 ECCI. All rights reserved.

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Course Objectives

By the end of the course, delegates should be able to:

understand the role and function of FMEA

understand the concepts and techniques of PROCESS FMEA and how to apply it.


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Introduction to FMEA

Definition, Origin, Application, Benefits,

Fitting FMEA with TQM and its role in a Quality System

Relationship of FMEA to other Standards and its Prerequisites

FMEA Proper

Design & Process FMEA

Applying FMEA

FMEA on Automotive Industry

Training Course Outline

• What is FMEA?

• History and Origin of FMEA

• Applications of FMEA

• Benefits

• Fitting FMEA with TQM

• Role of FMEA in a Quality System

• Relationship of FMEA to other Standards

• FMEA Prerequisites

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An Advance Quality Planning Tool used to evaluate Potential Failure

Modes and their Causes

Prioritizes Potential Failures according to their risk and drives action to eliminate or reduce their likelihood of occurrence



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Provides a disciplined methodology for documenting this analysis for future use and continuous process improvement

By itself, an FMEA is NOT a Problem Solver. It is used in combination with other problem solving tools.

“The FMEA presents the opportunity but does not solve the problem.”



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FMEA

Failure Mode and Effect Analysis – 1960’s and 70’s

First noticed and used by reliability engineers

System of various group activities provided through documentation of potential failure modes of products and or processes and its effect on product performance

The evaluation and documentation of potential failure modes of a product or process. Actions are then identified which could eliminate or reduce the potential failure.



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Prevention Planning

Identifies change requirements

Cost reduction

Increased through-put

Decreased waste

Decreased warranty cost

Reduced non-value added operations



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Quality Business

Objectives

Quality Business

Objectives

Problem Prevention

ProblemSolving

SpecialCharacteristics

SpecialCharacteristics

ControlPlan

ControlPlan

SPC ToolsSPC Tools

8 - D8 - D

Q O SQ O S

Process Improvement

Process Improvement

D O ED O E

F M E AF M E A

A P Q PA P Q P

F T AR F T AF T A

R F T A

Q F DQ F D



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Customer Input

Team – Team Selection (Cross-Functional)

Ranking – Ranking of Decisions

Risk Priority Assessment

Design Process

Production Process



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Is “… a summary of engineer’s/team’s thoughts (including an analysis of items that could go wrong based upon experience and past concerns) as a process is developed”.

A Process FMEA shall begin with a process flow chart/risk assessment of the general process. This flow chart should identify the product/process characteristics associated with each operation.

“Process Potential FMEA”

Relationship of FMEA to other Standards


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Before or After ?

Individual or Team Approach ?



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Select proper team and organize members effectively

Select teams for each product/service, process/system

Create a ranking system

Agree on format for FMEA matrix

Define the customer and customer needs/operations

Design/Process requirements

Develop a process flowchart

FMEA Prerequisites - Team


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What is a team ? Two or more who coordinate activities to accomplish . a common task or goal

Maintaining Focus A separate team for each product or project

Brainstorm Brainstorming (the Team) is necessary as the intent is to discover many possibilities.



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Representatives who have keyinformation or are stakeholders.

Assigned by steering committeeor upper management.

Assigned by or negotiated with steering committee or

upper management.

Disbands when task is finished.

Leadership shared or delegated by members.

Work area or unit.Representatives from support

groups on as-needed basis.

Participation is mandatory.

Assigned by management oridentified by team and within

its authority.

On-going

Leader appointed by management.

Membership

Member Selection

Project Identification

Team Life Span

Leadership

Natural Work Group Task Team

Two Types of Team Structures



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Are management directed and focused

Build their own identity

Are accountable and use measurements

Have corporate champions

Fit into organization

Are cross-functional or multi-disciplinary

Some teams just “Do not Work”



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Determine if there should be a meeting

Decide who should attend

Provide advance notices

Maintain minutes or records

Establish ground rules

Provide and follow and agenda

Evaluate meetings

Allow NO INTERRUPTIONS



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Clarify

Participate

Listen

Summarize

Stay on track

Manage Time

Test for consensus

Evaluate meeting process



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Start during prototype stage

Design Engineer - Generally the team leader

Team Members

Test Engineer Project Manager or Representative

Reliability Engineer Quality Engineer

Materials Engineer Customer Contact Person

Field Service Engineer Others, including Mfg, Sales,

Component Process Engineer Marketing, QA / QC, Process,

Vehicle Process Engineer Packaging.

Styling Engineer

FMEA Prerequisites – Design FMEA Team


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Process Engineer - Generally the Team Leader

Production Operator

Team Members

Industrial Engineer Styling Engineer

Design Engineer Project Manager or Rep.

Reliability Engineer Quality Engineer

Tooling Engineer Others incl. Supplier, Sales, QA/QC, Mfg.

Maintenance Engineer

FMEA Prerequisites – Process FMEA Team


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How do you CURRENTLYprevent problems from occurring?



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Design FMEA Customer

• End User; person who uses the product

• Use Failure

• This can help in Repair Manuals & Filed Service

• More in DFMEA section herein…

Process FMEA Customer

• Subsequent operations

• End User; person who uses the product

• More in the PFMEA section herein…

FMEA Prerequisites – Defining the Customer


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Design Failures & CausesDesign Failures & Causeswithwith

Process Failures & CausesProcess Failures & Causes

DESIGN FAILURES PROCESS FAILURES

Insufficient lubrication capability

Incorrect material specified

Insufficient lubrication applied

Incorrect material used

CAUTION!DO NOT MIX UP:


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RPN = (S) x (O) x (D)

S = Severity

O = Likelihood of Occurrence

D = Likelihood of DetectionPrevention vs Detection – Automotive Expectations

• 100 is the Maximum and 75 is considered “OK”

• High and low numbers are the important ones to consider

• Input Concept

FMEA Prerequisites – Creating Ranking System


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Process Function –

ReqmtsPotentialFailureMode

PotentialEffects of

Failure

SeverIty

PotentialCauses/

Mechanism(s) of

Failure

Occurrence

CurrentProcess Controls

DetectIon

R

P

N

Occurred

SeverIty

DetectIon

R

P

N

Recommended

Actionsand

Status

ResponsibleActivity

andTarget

CompletionDate

ActionsTaken

From Experience & Data

FromGuess

Item- Function

PotentialFailureMode

PotentialEffects of

Failure

SeverIty

PotentialCauses/

Mechanism(s) of

Failure

Occurrence

CurrentDesign Control

DetectIon

R

P

N

Occurred

SeverIty

DetectIon

R

P

N

RecommendedActions

andStatus

ResponsibleActivity

andTarget

CompletionDate

Pro

cess

FM

EA

Des

ign

FM

EA

Device /Process Cause Effect Control

Failure Mode Chance of Occurrence Severity Chance not detected

FMEA Prerequisites – Creating Ranking System

Design FMEA

Process FMEA

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Design FMEA

Design FMEA – is an analytical technique utilized primarily by a design FMEA team to ensure potential failure modes and their associated causes are identified, considered, and addressed.

Referenced in the AIAG FMEA Reference Manual.

This systematic approach parallels, formalizes an documents the mental discipline that an engineer normally goes through in any design process.


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Design FMEA foci

End User

• Repair Functions

• Dealership or other sales Outlet

• Designer of the next level system or product

• Process Engineers

• Assembly Engineers

• Test Engineers

• Product Analysis


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Typical Design Consideration

Design Intent

Customer Needs - can be specified and measured

Customer Wants - some cannot be explained

Product Requirements

Manufacturing Assembly Requirements

What the design is expected to do and what it is expected

not to do.

Think about what documents in your company

are used to define these

Quality Function DeploymentCustomer Contacts

Competitive AnalysisKnown Product Quality

Reliability RequirementsManufacturing Requirements

Start with a list of:


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Design FMEA Benefits

Aids in the objective evaluation of design requirements and alternatives.

Increases the probability that potential failure modes and their effects on the system/product have been considered.

Aids in the planning of design test and development programs.

Aids in analyzing field concerns, design changes and in developing advanced designs.

Ranks potential failure modes according to their effect on the customer, thus prioritizing improvements and development testing.

Provides an open issue format for recommending and tracking risk reducing actions.


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Design FMEA

The DFMEA

is a living document and should be initiated at, or by, design concept completion.

should be continually updated as changes occur throughout all phases of product development.

should be fundamentally complete along with the final product drawings.

addresses the design intent and assumes the design will be manufactures/assembled to this intent

The Potential Failure Modes/Causes which can occur during manufacturing or assembly process are covered by the Process FMEA and therefore should NOT be included in a Design FMEA.

More Design FMEA Considerations


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Causes of design failure modes are those things that, from a designer’s perspective, would, by

omission or

improper use, result in the

failure mode.

Design Failure CausesDesign FMEA


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Improper Tolerancing

Incorrect Stress Calculations

Wrong Assumptions

Wrong Material Call Out

Lower Grade Component

Lack of Design Standards

Improper Heat Treatment

Improper Torque Call Out

Design Failure Cause ExamplesDesign FMEA


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Body

Doors Exterior Window Interior

Door InnerPanel

GlassSealingw/ Strip

Latch/Lock

If the product function is complex, break it down into smaller subsystems. Identify

primary vs. secondary functions.

Design Block Diagram ExampleDesign FMEA


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Item-Function


PotentialEffects of

Failure

SeverIty

PotentialCauses/

Mechanism(s) of

Failure

Occurrence

CurrentDesign Control

DetectIon

R

P

N

Occurred

SeverIty

DetectIon

R

P

N

RecommendedActions

andStatus

ResponsibleActivity

andTarget

CompletionDate

FromGuess


Wording is important

DFMEA Basic Columns

Design FMEA


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HazardouswithoutWarning

Hazardouswith

Warning

Very high

High

Moderate

Low

Very Low

Minor

10

9

8

7

6

5

4

3

2

1

Very high severity ranking when a potential failure mode affects safevehicle operation and./or involves noncompliance with government

regulation without warning.

Very high severity ranking when a potential failure mode affects safevehicle operation and./or involves noncompliance with government

regulation with warning.

Vehicle/item inoperable, with loss of primary function.

Vehicle/item inoperable, but at a reduced level of performance. Customer dissatisfied.

Vehicle/item operable, but Comfort/Convenience item(s) inoperable. Customer experiences discomfort.

Vehicle/item operable, but Comfort/Convenience item(s) operable at reduced level of performance. Customer experiences some dissatisfaction,

Fit & Finish/Squeak & Rattle item does not conform. Defect noticed by most customers.

Fit & Finish/Squeak & Rattle item does not conform. Defect noticed by average customers.

Fit & Finish/Squeak & Rattle item does not conform. Defect noticed by discriminating customers.

No effect.

Very Minor

None

Effect Criteria: Severity of Effect Ranking

Generic Design FMEA SeveritySuggested Evaluation Criteria

Design FMEA


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Very High: Failure is almost inevitable

High: Repeated Failures

10

9

8

7

1 in 2

1 in 3

1 in 8

1 in 20

1 in 80

1 in 400

6

5Moderate: Occasional Failures

Low: Relatively Few Failures1 in 2,000

1 in 15,000

4

3

Remote: Failure Unlikely1 in 150,000

1 in 1,500,000

2

1

Probability of Failure Possible Failure Rates Ranking

Generic Design FMEA OccurrenceSuggested Evaluation Criteria

Design FMEA


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Detection Criteria: Likelihood of Detection by Design Control RankingAbsolute

Uncertainty

Very Remote

Remote

10

9

8

Design control will not and/or can not detect potential cause/mechanism and subsequent failure mode; or there is no Design Control.

Very remote chance the Design Control will detect a potential cause/mechanism andsubsequent failure mode.

Remote chance the Design Control will detect a potential cause/mechanism and subsequent failure mode.

Very Low

Low

Very low chance the Design Control will detect a potential cause/mechanism andsubsequent failure mode.

Low chance the Design Control will detect a potential cause/mechanism and subsequent failure mode.

7

6

ModerateModerate chance the Design Control will detect a potential cause/mechanism and

subsequent failure mode.5

ModeratelyHigh

Moderately high chance the Design Control will detect a potential cause/mechanism and subsequent failure mode.

4

HighHigh chance the Design Control will detect a potential cause/mechanism and

subsequent failure mode.3

2

1

Very high chance the Design Control will detect a potential cause/mechanism and subsequent failure mode.

Design Control will almost certainly detect a potential cause/mechanism and subsequent failure mode.

Very High

Almost Certain

Generic Design FMEA DetectionSuggested Evaluation Criteria

Design FMEA


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Design controls are those actions taken as a normal part of the development process that are designed into the process to minimize the occurrence of failure or to

detect specific failure modes.

Design controls should directly relate to the

Prevention and/or Detection of specific

causes of failures.

Design FMEA


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Designed Experiments

Finite Element Analysis

Variation Simulation

FT Analysis

Component Derating (60% to 80%)

100,000 Mile Pilot Test

Reliability Tests/Prototype Testing

Design Reviews

Worst Case Stress Analysis

Robust Design

Environmental Stress Testing

ConsiderInterpretation

of Data

Design Control ExamplesDesign FMEA


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When the failure modes have been ranked by their RPN, corrective actions should be first directed at the highest ranked concerns and critical items identified.

The intent of any recommended action is to reduce one or more (or all) of the occurrence, severity and/or detection rankings.

Only a design revision can bring about a reductionreduction in the severity ranking. If no actions are recommended for a specific cause, this should be indicated.

Design FMEA


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(Continued)

A reduction in the occurrence ranking can only be effected by removing or controlling one or more of the causes of the failure mode through a design revision.

An increase in design verification actions will result in a reduction in the detection ranking ONLY.

Design FMEA does not rely on process controls to overcome weaknesses in the design; however, it does take technical and physical limitations of a process into consideration (Design Rules).

Design FMEA


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Process FMEA


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Sample Sizes

EvaluationFrequency

Method of Evaluation

Out-of-ControlAction Plan

(OCAP)

IdentifiesCritical and Significant

Characteristicsand is therefore

theStarting Point

for theControl Plan

The Process FMEAThe Process FMEA

Process FMEA


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Use a Process Flow Chart!Because:

You want to understand your current process

You are looking for opportunities to improve

You want to illustrate a potential solution

You have improved a process and want to document the new process

Process Flow Chart


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Identify the process or task you want to analyze.

Ask the people most familiar with the process to help construct the chart.

Agree on the starting point and ending point.

Agree on the level of detail you will use.

Look for areas of improvement

Is the process standardized, or are the people doing the work in different ways?

Are steps repeated or out of sequence?

Are there steps that do not add value to the output?

Are there steps where errors occur frequently?

Are there rework loops?

Creating a Process Flow Chart


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(Continued)

Identify the sequence and the steps taken to carry out the process.

Construct the process flow chart either from left to right or from top to bottom, using the standard symbols and connecting the steps with arrows.

Analyze the results

Where are the rework loops?

Are there process steps that do not add value to the output?

Where are the differences between the current and the desired situation?

Creating a Process Flow Chart


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A summary of the engineer’s and the team’s thoughts (including an analysis of items that could go wrong based on experience and past concerns) as a process is developed in the manufacturing planning process.

Process FMEA


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Identifies potential product-related failure modes

Assesses the potential customer effects of the failures

Identifies the potential internal and external manufacturing or assembly process causes and identifies process variables on which to focus controls for occurrence reduction and/or detention of the failure condition(s).

Develops ranked list of potential failure modes, thus establishing a priority system for corrective action considerations.

Documents the results of the manufacturing or assembly process

Process FMEA


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Teams should be run by the owner of the process or someone who understands the process well.

Defines reasons for rejection at specific operations.

In preparation for the FMEA, the assumption should be made that the incoming parts and materials are correct.

A comparison of similar processes and a review of customer claims relating to similar components is a recommended starting point. A knowledge of the purpose of the design is necessary.

It can be cause-associated with a potential failure mode in a subsequent operation or an effect associated with a potential failure in a previous operation.

Each potential failure mode for the particular operation should be listed in terms of a part or process characteristic.

Process FMEA


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end user

next manufacturing or process step

process engineers

assembly engineers

repair functions

test engineers

product analysis

dealership or other sales outlet

Process FMEA

The Customer


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The Process Potential FMEA - identifies potential product related process failure modes

- assesses the potential customer effects of the failures

Process FMEA

As a systematic approach, the Process Potential FMEA parallels and formalizes the mental discipline that an engineer goes through in any manufacturing planning process.


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Process FMEA

(Continued)

identifies potential manufacturing and/or assembly process causes

identifies significant process variables to focus controls for occurrence reduction and detection of failure conditions.

develops a list of potential failure modes ranked according to their effect on the customer, thus establishing a priority system

for corrective and preventive action considerations.


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The PFMEA

is a living document.

should be continually updated as changes occur throughout all phases of product development and on into and through to the end of production.

should begin with a flowchart of the process - from receiving through shipping and warehousing

addresses the design intent and assumes the design will be manufactures/assembled to this intent

The Potential Failure Modes/Causes which can occur during manufacturing or assembly process are covered by the Process FMEA but some information (severity rankings, identification of some effects) MAY come from Design FMEA.

Process FMEA More Process FMEA ConsiderationsMore Process FMEA Considerations


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ProcessFunction

Requirements


PotentialEffects of

Failure

SeverIty

PotentialCauses/

Mechanism(s) of

Failure

Occurrence

CurrentProcess Controls

DetectIon

R

P

N

Occurred

SeverIty

DetectIon

R

P

N

RecommendedActions

andStatus

ResponsibleActivity

andTarget

CompletionDate

ActionsTaken

Wording is important


FromGuess

Process FMEA Generic PFMEA Basic ColumnsGeneric PFMEA Basic Columns

Customer Complaints

Warranty & Repair Info.

Internal Scrap & Rework History

FMEA Team Expertise

(Brainstorming)

• Brainstorming Principles

• Process Flow Diagrams

• Starting FMEA

• FMEA Roadmap

• FMEA Priority Actions

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Brainstorming attempts to generate a list of ideas that can be evaluated and refined by the whole team

In a brainstorming session:

Criticism is NOT allowed

Evaluation of ideas is held off until a later stage

“Free-wheeling” is welcome

All ideas are welcome; nothing is refused

Quantity is desired - the more ideas the better

Hitchhiking is encouraged - build upon and improve upon ideas of other

Suggestions for “pumping” ideas:

Trigger session - Round Robin

Pass the buck

BRAINSTORMING Principles


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Flow diagrams provide a process overview at a glance. It assists in:

Identifying process customers

Specifying where is value is added

Relating one step to other steps

Determining appropriate data collection and control points

Highlighting work place deficiencies

Promoting teamwork, understanding and decision-making

Process Flow Diagrams


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STEP # 1: Determine the Process to be Considered

The use of process flow diagrams provide a process overview at a glance and shows process functions/behaviors.

The conduct if FMEA is limited to the current level of understanding of process behaviors. Anything beyond the level of comprehension at a time of drafting should not be included.

Process function should be as mush as possible be expressed in verb-noun function.

Starting FMEA


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Process function expressed asVerb-Noun

Process function expressed asVerb-Noun

Failure mode (s)Failure mode (s)

Absence of Function

Absence of Function

“Does not, no”

“Does not, no”

Function done poorly,

inadequately or incompletely

Function done poorly,

inadequately or incompletely

Express inDirectional or

Actionable terms

Express inDirectional or

Actionable terms

Starting FMEASTEP # 2: Brainstorm the Potential Failure Modes that are Generated by the Process


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When defining failure modes - assume prior steps and incoming materials (inclusive of the units to be processed) are perfect.

STEP # 2: Brainstorm the Potential Failure Modes that are Generated by the Process

Starting FMEA


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An effect of a failure is the consequence (s) of a failure mode that would be noticed or experienced at the next station, or a subsequent operation, by a downstream user or by the ultimate customer.

Customers are defined as next-in-line customer rather than the end-user.

Look at effects from within, up to the next immediate process. If the particular failure mode has experiences of ending up at the customer, indicate a note to properly effect the severity rating.

Consider: next user, downstream user, ultimate customer, product operation, safety, government regulations

Starting FMEA

STEP # 3: Identify Potential Effects of Each Failure Mode


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PEOPLE

METHODS

MACHINERY

ULTIMATECUSTOMER

MATERIALSFAILURE

MODE

DOWNSTREAM USER

NEXT OPERATION

ENVIRONMENT

POTENTIAL EFFECTS

Starting FMEA

Cause & Effect Diagram

POTENTIAL CAUSES


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SEVERITY :

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

Starting FMEA

STEP # 4: Determine the Severity of the Effect


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SEVERITY is an assessment

of the seriousness of the

effect of the potential

failure mode to the

customer.

SEVERITY applies to the

effect only.

Process FMEA

Generic Process FMEA Severity


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Process FMEA – Suggested Severity Criteria Criteria : Severity of Effect Criteria : Severity of Effect

This ranking results when a potentialfailure mode results in a final customerand/or a manufacturing / assembly plantdefect. The final customer should alwaysbe considered first. If both occur, use thehigher of the two severities.

This ranking results when a potentialfailure mode results in a final customerand/or a manufacturing / assembly plantdefect. The final customer should alwaysbe considered first. If both occur, use thehigher of the two severities.

(Customer Effect) (Manufacturing/Assembly Effect)Hazardous Without warning

Very high severity ranking when potential failuremode affects safe vehicle operation and/orinvolves noncompliance with governmentregulation without warning

or may endager operator (machine orassembly) without warning.

10

Hazardous with warning

Very high severity ranking when potential failuremode affects safe vehicle operation and/orinvolves noncompliance with governmentregulation with warning.

or may endager operator (machine orassembly) with warning.

9

Very high Vehicle/item inoperable (loss of primaryfunction)

or 100% of product may have to be scrapped,or vehicle/item repaired in repair departmentwith a repair time greater than one hour.

8

High Vehicle/item operable, but a reduced level ofperformance. Customer very dissatisfied.

or product may have to be sorted and a portion(less than 100%) scrapped, or vehicle/itemrepaired in repair department with repair timebetween a half hour and an hour.

7

Moderate Vehicle/item operable, but comfort /convenience item(s) inoperable. Customerdissatisfied.

or a portion (less than 100%) of the productmay have to be scrapped without sorting, orvehicle/item repaired in repair item with a repairtime less than half hour.

6

Low Vehicle/item operable, but comfort /convenience item(s) operable at a reduced levelof performance.

or 100% of product may have to be reworked, or vehicle/item repaired off line but does not go torepair department.

5

Very low Fit and finish/squeak and rattle item does notconform. Defect noticed by most customers(greater than 75%)

or the product may have to sorted, with noscrap, and a portion (less than 100%)reworked.

4

Minor Fit and finish/squeak and rattle item does notconform. Defect noticed by 50% of customers.

or a portion (less than 100%) of the productmay have to be reworked, with no scrap, on linebut out of station.

3

Very minor

Fit and finish/squeak and rattle item does notconform. Defect noticed by discriminatingcustomers (less than 25%)

or a portion (less than 100%) of the productmay have to be reworked, with no scrap, on linebut in station.

2

None No discernible effect. or slight inconvenience to operation or operator,or no effect.

1

Effect Ranking


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CAUSE:

A cause of a failure mode is a deficiency that results in a failure mode. It is description of how the process could result in a failure.

Must consider: method, machinery, materials, people and environment

Be specific! General statements such as “equipment malfunction” must not be used.

Use only first level causes for this analysis.

Deal on real issues and not on operator issues. Assume operators will do their best. This leaves us to focus on systematic failures with actionable causes.

Starting FMEA

STEP # 5: Determine Potential Cause for each Failure Mode


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01. Omitted processing 02. Processing errors 03. Errors setting up work pcs 04. Missing parts 05. Wrong parts 06. Processing wrong work pc 07. Mis-operation 08. Adjustment error 09. Equipment not set up properly 10. Tools and/or fixtures improperly prepared

11. Poor control procedures 12. Improper equipment maintenance 13. Bad recipe 14. Fatigue 15. Lack of safety 16. Hardware Failure 17. Failure to enforce controls 18. Environment 19. Stress connections 20. Poor FMEA(s)

Process FMEA

Process Failure CausesProcess Failure Causes


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OCCURRENCE

Is rated as the number of times the cause has resulted in the failure mode before any additional process control are applied. The rating should be based on actual records such as machine downtime report, process yield and defects report, SPC log of activities, extent of reworks, production reports, etc.

The occurrence rating of each cause should reflect the relative occurrence of both the failure and cause.

Starting FMEA

STEP # 6: Rank the Occurrence of each Cause


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OCCURRENCE is how

frequently the specific

failure cause

/mechanism is

projected to occur.

Process FMEA

Generic Process FMEA Occurrence


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Probability of Failure Possible Failure Rates Ranking

Very High: Persistent failures

High: Frequent failures

Moderate: Occasional failures

Low: Relatively few failures

100 per thousand pieces


10

9

8

7

6

5

4

3

2

1






0.5 per thousand pieces

0.1 per thousand pieces

Remote: Failure unlikely. < 0.01 per thousand pieces

Process FMEA

Generic PFMEA OccurrenceSuggested Evaluation Criteria


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DETECTION :

Detection is rating corresponding to the likelihood that current process will detect the failure mode before it gets to the customer

In identifying detection (D) process controls, remember that if it is not rejecting units it will not be considered as a “D” control.

Detection (D) type controls must be as close as possible to the process itself for instantaneous feedback.

Starting FMEA

STEP # 7: Identify the Process Controls that are currently used to detect the failure mode or prevent the cause


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Detection (D) controls must treat each defined process step. Never consider those “D” controls too far down the line.

Do not rate prevention (P) controls as you have them rated already in the occurrence.

Detection should not be related to occurrence; detection indicates the likelihood of a failure that has occurred.

Assume that a failure has occurred to detection rating.

REMEMBER:

Controls are for causes or failure modes, but the Detection ranking only applies to controls for Failure Modes, I.e., for “D” controls not on “P” controls.

Starting FMEA

STEP # 7: Identify the Process Controls that are currently used to detect the failure mode or prevent the cause


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DETECTION is an assessment of the probability that the proposed type (2) current process controls will detect a potential

cause/mechanism (process weakness), or the probability that

the proposed type (3) process controls will detect the subsequent failure mode, before the part of the

component leaves the manufacturing operation or assembly location.

Process FMEA

Generic Process FMEA Detection


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Assume the failure has occurred and then assess the

capabilities of all current controls to prevent shipment of

the part having this failure mode or defect.

Random quality control checks would be unlikely to detect

the existence of an isolated defect and therefore would result

in low to remote detection ranking.

Sampling done on a statistical basis is valid detection control.

A reduction in detection ranking can only be achieved by

improving process control system(s).

Process FMEA

Generic Process FMEA Detection (continued)


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01. Standardized work instructions/procedures

02. Fixtures and jigs

03. Mechanical interference interfaces

04. Mechanical counters

05. Mechanical sensors

06. Electrical/Electronic sensors

07. Job sheets or Process packages

Controls can beprocess controls

suchas fixture

fool-proofingor SPC,

or can be post-process

inspection/testing.

Process FMEA Process Control ExamplesProcess Control Examples


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08. Bar coding with software integration and control

09. Marking

10. Training and related educational safeguards

11. Visual checks

12. Gage studies

13. Preventive maintenance

14. Automation (Real Time Control)

Inspection/testingmay occur at thesubject operation or at subsequent

operation(s) that can

detect the subject failure mode.

Process FMEA Process Control Examples Process Control Examples (continued)(continued)


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SPC Records

Visual aids

Work instructions

Inspection instructions/records

Equipment operating instructions

Training records

Traceability records

Process FMEA


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Process FMEA – Suggested Detection Criteria

A B CAlmost impossible

Absolute certainty of non detection

X Cannot detect or is not checked. 10

Very Remote

Controls will probably not detect.

X Control is achieved with indirect or random checksonly.

9

Remote Controls have poor chance of detection

X Control is achieved with visual inspection only. 8

Very Low Controls have poor chance of detection

X Control is achieved with double visual inspection only. 7

Low Controls may detect. X X Control is achieved with charting methods, such asSPC (Statistical Process Control)

6

Moderate Controls may detect. X Control is based on variable gauging after parts leftthe station, or Go/No Go gauging performed on 100%of the parts after parts have left the station.

5

Moderately high

Controls have a good chance to detect.

X X Error detection in subsequent operations, OR gaugingperformed on set up and first piece check (for set upcauses only).

4

High Controls have a good chance to detect.

X X Error detection in station, or error detection insubsequent operations by multiple layers ofacceptance: supply, select, install, verify. Cannotaccept discrepant part.

3

Very high Controls almost certain to detect.

X X Error detection in station (automatic gauging withautomatic stop feature). Cannot pass discrepant part.

2

Very high Controls certain to detect. X Discrepant parts cannot be made because item hasbeen error proofed by process/product design.

1

Ranking

Suggested PFMEA Detection Evaluation Criteria

Inspection TypesDetection Criteria Suggested Range of Detection Methods


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RPN

The RN is a measure of process risk and should be used to rank order the risks/concerns. It is calculated by getting the product of:

SEVERITY x OCCURRENCE x DETECTION

For RPN calculation purpose, the following must be observed:

The largest severity score will be used from among the severity score.

The largest occurrence rating will be applied for calculation

However, for detection score - the lowest score is utilized

Starting FMEA

STEP # 8: Calculate RPN


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Corrective action measures must be taken to reduce the risk for the following conditions:

Severity is <5.

It has the highest S*O rating

It belongs to the top 3 RPN’s (but not necessary)

RPN >100.

Note: These conditions only serve as a guide in prioritizing corrective actions. Eng’g findings and decisions will still hold through.

Starting FMEA

STEP # 9: Plan appropriate Corrective Action based on RPN


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The purpose of any action is to reduce the occurrence and/or

detection ranking. The action plan should include:

Recommended action : must be defined to reduce the risk

associated

Responsibility - the organization and/or individual responsible for

the action and the target date of completion.

Action taken - a brief description of the actual completed action and

the effective date.

Resulting RPN - after C/A has been taken, the occurrence and

detection ranking must be defined and the RPN recalculated.

STEP # 9: Plan appropriate Corrective Action based on RPN

Starting FMEA


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Corrective action should be first directed at the

highest concerns as rank ordered by RPN.

The intent of any recommended action is to reduce

the occurrence, severity and/or detection rankings.

If no actions are recommended for a specific

cause, then this should be indicated.

Process FMEA


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Only a design revision can bring about a reduction in the severity

ranking.

To reduce the probability of occurrence, process and/or

specifications revisions are required.

To increase the probability of detection, process control and/or

inspection changes are required.

Improving detection controls is typically costly. The emphasis should

be placed on preventing, rather than detecting, defects.

(Continued)

Process FMEA


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Eng’g is responsible for assuring that the recommended actions

have been adequately addressed and implemented.

An FMEA is a living document and should always reflect the latest

process as well as the latest actions.

Events when FMEA should be reviewed:

A change (I.e., added, deleted or altered) in the process or

equipment

When process improvements or problems have potential to alter

the RPN due to a change in severity, occurrence or detection

As actions or results are documented/implemented

Starting FMEA

STEP # 10: FMEA Follow-up Review and Revision


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POTENTIAL FAILURE MODEPOTENTIAL FAILURE MODE

EFFECTEFFECT

CAUSECAUSE

CURRENT CONTROLSCURRENT CONTROLS

DETERMINE OCCURRENCEDETERMINE OCCURRENCE

DETERMINE SEVERITYDETERMINE SEVERITY

DETERMINE DETECTABILITYDETERMINE DETECTABILITY

ACTIONS LEADING TOCONTINUOUS IMPROVEMENT

ACTIONS LEADING TOCONTINUOUS IMPROVEMENT

DETERMINE RPNDETERMINE RPN

FMEA Roadmap


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SEVERITY

OCCURRENCE

DETECTION

Changing design (material,

geometry, etc)

Changing designor process

Adding/improvingcontrols/methods

Eliminating failuremode

Preventing or reducing

occurrences of one

or more causes

Improving ability

to detect thefailure mode

FMEA Priority Actions


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The Team Developing the FMEA turns out to be One Individual

The FMEA is created to satisfy a customer or third party requirement, NOT to improve the process.

The FMEA is developed too late in the process and does not improved the product/process development cycle.

The FMEA is perceived either as too complicated or as taking too much time.

Wrong approach to FMEA and its Misconception