Function:Function of the item being analyzed 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 include, not limited to:

Yield; Fatigue; Material Instability; creep; wear; corrosion; Cracked Deformed; Leaking

What is FMEA?FMEA is a systemised group of activities to:•Recognise and evaluate the potential failure of a product / process and its effects•Identify actions which could eliminate or reduce the chance of potential failure occurring•Document the process

Why FMEA?•For a company policy where continuous improvement is emphasized for its product, process•FMEA is a living document

Who should do FMEA?•Cross Functional Team Effort – with a leader•Team of knowledgeable individuals Ex. Expertise in Design, Mfg., Assly, Quality. Etc.•Team should include representatives of sub-contractors and/or customers

QS-9000 requirements•FMEA shall consider special characteristics•Aiming defect prevention rather than defect detection•Use FMEA manual & CFT approach

When FMEA should be done?Essence is timeliness•Pro-Active rather than reactive•Before process failure mode occursAdvantages of FMEA•Avoids late change crisis•Reduces or eliminates chance of implementing corrective change•excellent technique for preventive action•interactive process which is never ending

Process

Function/ Requirements

Potential Failure Mode

Potential Effect(s) of Failure

Specify the description and Function of the process

List out Outputs of the Process

ExampleProcess function / description

- Manual application of wax inside door- Machining of outer diameterRequirements- To cover inner door at minimum thickness to

retard corrosion- Outer diameter, run-out, free from tool mark

Potential Failure Mode Potential Effect(s) of Failure

Sev

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

against the requirements specified in the previous column.

Apart from Engg. Specification, what would a customer consider objectionable

CUSTOMER is- Next opn.- Subsequent Opn.- End user ExampleBent, Diameter oversize, Diameter undersize, Cracked, Deformed, Open Circuited, BurredOD not clear – Is it a failure mode in machining of casting / forging?

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 the terminology specified in Severity

rating table For each failure mode, more than one effect can be listed

Severity

Class

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

Assess the seriousness of the effect in a 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)

ClassificationPotential Cause(s) /

Mechanism (s) of Failure

Occur

Classify special product characteristics (e.g. critical, key, major)

Potential Cause(s) / Mechanism (s) of Failure Occur

Current Process Control

prevention

Current Process Control

detection

List the first level potential causes such as - man- machine- tool- process parameter- Fixture etc. List the root causes under the first level causes using

WHY? WHY? analysis Describe the causes in such a way that can be eliminated

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.….

Occurrence

Current Process Controls

prevention

Current Process

Controls

Detection

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 team judgementDon’t consider failure-detecting measures while giving ranking (100% inspection.)

Current Process Control

Prevention

Current Process Control

Detection

Detect

RPN

Type of Controls

Level Type Examples

P-Prevention Prevention of causes Mistake proofing

D- Detection

Detection of causes & leading to corrective actions Detection of defect

SPC, Visual control etc. 100% inspection, patrol inspection

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

Detection RPN Recommended Action

Assess the probability of controls listed in the previous column, which will detect the cause or failure mode

While giving ranking, assume the failure is occurred Don’t assume ranking is low because the occurrence is

low Random controls should not influence detection

ranking One detection ranking can be assigned to multiple

controls

Recommended Action

Responsibility

& Target Completion Date

Action Results

Policy for RPN to take action - Define a target RPN and anything above that can be

considered for action. For Ex. It can be 50. Considering 95% of the failures are attended

- consider only high priority no. for take action and review periodically

As a first priority, take action on causes to reduce occurrence ranking

The next priority is to consider action on controls to reduce detection ranking

severity ranking can be reduced by - elimination of failure mode by change in processes or

design

Responsibility & Target Completion DateActions Taken

SevOcc

De t

RPN

Specify the responsibility and target completion date for every actions identified

During APQP, the FMEA completion dates should be prior to Production run

PROCESS FMEA QUALITY OBJECTIVES•PROCESS IMPROVEMENTS: The FMEA drives process improvement as primary objective. With an emphasis on Error / Mistake proofing solutions •HIGH RISK FAILURE MODES: The FMEA address all high-risk failure modes as identified by FMEA team, with executable action plans. All other failure modes are considered. •CONTROL PLANS: The pre launch and production Control Plan consider the failure modes from the process FMEA. •INTEGRATION: The FMEA is integrated and consistent with process flow diagram and the process control plan. The process FMEA considers the design FMEA, if available as part of its analysis. •LESSONS LEARNED: The FMEA considered all major “ lessons learned “ as input to failure mode identification •SPECIAL OR KEY CHARACTERISTICS: The FMEA identifies appropriate key characteristics candidates as input to the key characteristics selection process, if applicable due to company policy. •TIMING: The FMEA is completed during the “Window of opportunity “where it could most efficiently impact the product design of product or process.•TEAM: The right people participate as part of the FMEA team throughout the analysis and are adequately trained in FMEA methods •DOCUMENTATION: The FMEA is completely filled out “by the book” including “action plan” and new RPN values.•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.

Action Results

Actions Taken Sev Occ Det RPN

Describe the verification results Where effectiveness measure is required, specify

the target date accordingly After the assessment of the actions taken, re-

assess the values of severity, occurrence, detection and RPN