Fmea Process

Nathan & Nathan Consultants Pvt. Ltd. NNCPL/PPT/006 1.

PROCESS FMEAPROCESS FMEA

FAILURE MODE & EFFECT ANALYSISFAILURE MODE & EFFECT ANALYSIS

PFMEAPFMEA


PROCESS FMEAPROCESS FMEAF

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OriginUS-Space program and defence safety system in 1960’s

Common Definitions Function :

Function of the item being analysed to meet the Design intent. Includes information regarding the environment in which this system operates.

Failure Mode:

A ‘Failure Mode’ is the manner in which a component, assembly or system could potentially fail to meet the design intent. Typical failure mode may includes, not limited to :

Yield; Fatigue; Material Instability; creep; wear; corrosion;

Cracked Deformed; Leaking.


PROCESS FMEAPROCESS FMEAWhat is FMEA?

FMEA is a systemised group of activities to:

1. recognise and evaluate the potential failure of a product /

process and its effects

2. identify actions which could eliminate or reduce the chance

of potential failure occurring

3. document the process

Why FMEA ?

1. For a company policy where continuous improvement is

emphasized for its product, process

2. FMEA is a living document

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ME

A Who should do FMEA?

1. Cross Functional Team Effort – with a leader

2. Team of knowledgeable individuals Ex. Expertise in Design,

Mfg., Assly., Quality., etc.

3. Team should include representatives of sub-contractors and/or

customers

When FMEA should be done ?

1. Essence is timeliness

2. Pro-Active rather than reactive

3. Before process failure mode occurs



ME

A Advantages of FMEA

1. Avoids late change crisis

2. Reduces or eliminates chance of

implementing corrective change

3. excellent technique for preventive action

4. interactive process which is never ending

Types of FMEA

1. System FMEA – Power transmission system

2. Design FMEA – Axle shaft

3. Process FMEA – Heat treatment



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A QS-9000 requirements

FMEA shall consider special characteristics Aiming defect prevention rather than defect detection Use FMEA manual & CFT approach

Potential – Process FMEA

Potential Means ‘Anticipated’

It is an analytical technique to assure that potential failure

mode and their associated causes have been considered and

addressed.



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FOR FMEA FORMAT

CLICK HERE


PROCESS FMEAPROCESS FMEAE

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Function/ RequirementsPotential Failure

Mode

PotentialEffect(s) of

Failure

Specify the description andFunction of the process

List out Outputs of the Process

ExampleProcess function / description- Manual application of wax

inside door- Machining of outer diameter

Requirements- To cover inner door at minimum

thickness to retard corrosion- Outer diameter, run-out, free

from tool mark



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Potential Failure Mode PotentialEffect(s) of

Failure

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Two Assumptions are1. Consider all inputs are acceptable2. Consider the Design is acceptable List the failure modes those are

possible to occur against therequirements specified in theprevious column.

Apart from Engg. Specification, whatwould a customer considerobjectionable

CUSTOMER is- Next opn.- Subsequent Opn.- End user

ExampleBent, Diameter oversize, Diameterundersize, Cracked, Deformed, OpenCircuited, BurredOD not clear – Is it a failure mode inmachining of casting / forging?



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Potential Effect(s) of Failure Sev Class List the effects of failure in

- Next operation- Subsequent operations- Customer- End user/ Environment

Describe the effects using theterminology specified in Severity ratingtable

For each failure mode, more than oneeffect can be listed

Example- Cannot locate- Cannot face- Does not fit- Does not match- Scrap, re-work- Vehicle / item inoperable- Loss of primary function- Customer dissatisfaction



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FOR SEVIORITY RANKING

CLICK HERE

Severity ClassPotential Cause(s)/ Mechanism (s) of

Failure

Assess the seriousness of the effect ina 1-10 scale

This rating applies to EFFECT only(i.e. previous column)

Consider the Design FMEA Consult subsequent Mfg./ Assembly

plant Safety related effects should be rated

in Nos.9 or 10 While giving ranking consider only the

required criteria (i.e. next opn. /vehicle)



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Classification

PotentialCause(s) /

Mechanism(s) of Failure

Occur

Classify special productcharacteristics (e.g. critical,key, major)



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Potential Cause(s) / Mechanism (s) of FailureOccur

CurrentProcessControl

prevention


detection

List the first level potential causes such as- man- machine- tool- process parameter- fixture etc.

List the root causes under the first level causesusing WHY? WHY? analysis

Describe the causes in such a way that can beeliminated or controlled

Don’t use ambiguous statements such as- operator mal-functioning- fixture problem etc.

Use the cause and effect diagram, if required consider input materials in last iteration of cause

analysis

Contd.….



Potential Cause(s) / Mechanism (s) of FailureOccur


Prevention


detectionExampleUnder Man

- Fails to clean- Fails to assemble- Fails to tight- Mis-locate

Under machine- inadequate lubrication- excessive vibration- excessive spindle run-out

Under process- improper time / temperature- inadequate gating / venting

Under design- Symmetric design- Difficult to assemble

Under Raw Material- Mixed material- New source- Alternate material- Excessive hardness



Occurrence

CurrentProcessControlspreventi

on

CurrentProces

sControl

sDetecti

on Estimate the probability of

occurrence on a 1-10 scale Rate against each causes Use past data as a basis

(cpk/rejection %) for ranking Document the basis of

occurrence ranking For a new process, if there is no

previous experience, use teamjudgement

Don’t consider failure-detectingmeasures while giving ranking(100% inspection.)

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FOR OCCURANCE RANKING

CLICK HERE



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PreventionCurrent Process Control

Detection

Detect

RPN

Type of Controls

Level Type ExamplesP-Prevention

Prevention ofcauses

Mistake proofing

D-Detection

Detection of causes& leading tocorrective actionsDetection of defect

SPC, Visualcontrol etc. 100%inspection, patrolinspection

List the existing controls, which can detect the causes or failure mode While listing, specify the frequency of detection measures

Examples- Visual Check, one per shift for film thickness- SPC chart five pieces in an hour- On-line monitoring of crimping force- Auto-control of temperature- 100% on-line inspection- Visual monitoring of Ammeter



FOR DETECTION RANKING

CLICK HERE

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Detection RPNRecommended

Action

Assess the probability of controlslisted in the previous column,which will detect the cause orfailure mode

While giving ranking, assume thefailure is occurred

Don’t assume ranking is lowbecause the occurrence is low

Random controls should notinfluence detection ranking

One detection ranking can beassigned to multiple controls



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RPNRecommended Action

Responsibility & TargetCompletion

Date

Risk Priority Numberis the multiplication ofseverity x occurrencex detection.

While calculatingRPN, consider onlyhighest severity ratingof each failure mode



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Recommended Action

Responsibility& Target

CompletionDate

ActionResults

Policy for RPN to take action- define a target RPN and anything

above that can be considered foraction. For Ex. It can be 50.Considering 95% of the failures areattended

- consider only high priority no. fortake action and review periodically

As a first priority, take action on causesto reduce occurrence ranking

The next priority is to consider actionon controls to reduce detection ranking

severity ranking can be reduced by- elimination of failure mode by

change in processes or design



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Responsibility & TargetCompletion Date

Actions

Taken

Sev

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RPN

Specify the responsibilityand target completion datefor every actions identified

During APQP, the FMEAcompletion dates should beprior to Production run



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Action Results

Actions TakenSev

Occ

Det RPN

Describe the verification results Where effectiveness measure is

required, specify the target dateaccordingly

After the assessment of theactions taken, re-assess thevalues of severity, occurrence,detection and RPN



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Follow up actions

The Process - responsible engineer is responsible for ensuring that all

actions recommended have been implemented or adequately addressed

. FMEA is a living document and should always reflect the latest design

level as well as the latest relevant actions.

The Process responsible engineer has several means of ensuring that

concerns are identified and that recommended actions are implemented .

they includes but not limited to followings :

1 Ensuring design requirements are achieved

2 Reviewing engineering drawings & specifications

3 Conforming incorporation in assembly / manufacturing

documentation &

4 Reviewing process FMEA & Control plans


PROCESS FMEAPROCESS FMEAP

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PROCESS FMEA QUALITY OBJECTIVES

1 PROCESS IMPROVEMENTS: The FMEA drives process improvement asprimary objective. With an emphasis on Error / Mistake proofing solutions

2 HIGH RISK FAILURE MODES: The FMEA address all high-risk failuremodes as identified by FMEA team, with executable action plans. All otherfailure modes are considered.

3 CONTROL PLANS: The pre launch and production Control Plan consider thefailure modes from the process FMEA.

4 INTEGRATION: The FMEA is integrated and consistent with process flowdiagram and the process control plan. The process FMEA considers thedesign FMEA, if available as part of its analysis.

5 LESSONS LEARNED: The FMEA considered all major “ lessons learned “ asinput to failure mode identification

6 SPECIAL OR KEY CHARACTERISTICS: the FMEA identifies appropriatekey characteristics candidates as input to the key characteristics selectionprocess , if applicable due to company policy.


PROCESS FMEAPROCESS FMEAD

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ES 7 TIMING: The FMEA is completed during the “ Window of opportunity “

where it could most efficiently impact the product design of product or

process.

8 TEAM: The right people participate as part of the FMEA team through

out the analysis and are adequately trained in FMEA methods

9 DOCUMENTATION: the FMEA is completely filled out “ by the book ”

including “ action plan ” and new RPN values.

10 TIME USAGE: Time spent by FMEA team as early as possible is an

effective & efficient use of time, with a value –added result. This

assumes recommended actions are identified as required and the

actions are implemented.

Fmea Process

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