FMEA METHODOLOGY.ppt

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PotentialFAILURE MODE AND

EFFECT ANALYSIS

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It is a specific methodology to evaluate a system, design, process or services for possible ways in which failures can occur and help identify actions which could eliminate or reduce the chance of failure occuring

INTRODUCTION

For each of the failures identified an estimate is made of its effect on total system/design, its causes and its control method.

It is a prevention based methodology, Defect prevention is most effective, if it is done before product/process is launched/designed.

The cost of defect rectified during product/process launch is far greater than same defect identified and rectified during design/drawing stage itself

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It will help to reduce the number of complaints and failures after product launch and despatch.

INTRODUCTION

FMEA is a structured mean for evaluating the problem that are likely to be encountered and the consequences of such problem.

This is also useful for evaluating the effects of significant engineering changes or product/process designs.

FMEA is of two type 1. Design FMEA 2.Process FMEA

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HISTORY The failure mode and effect analysis (FMEA) has been

developed at the mid-sixties in the USA for the Apollo Project by the NASA.

After applying that method in aeronautics and the aerospace industry, as well as in the nuclear technology, its usage had been introduced soon in the automobile industry.

The FMEA finds now globally a widespread application.

The FMEA nowadays a methodical component of quality management systems for many automobile manufacturers and their suppliers.

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Increase in performance,reliability,dependability of products Reducing of guaranty cost and goodwill commitments Shorten development processes. Less chance to failures during start of series

production

Improve faithfulness to deadlines

More economical manufacturing

Improved services

Improved internal communication

Advantages of FMEA

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Advantages of FMEA

Providing additional information to aid in the planning of thorough and efficient design test and development programs. Developing a list of potential failure modes ranked

according to their effect on “customers”. Providing an open issue format for recommending

and tracking risk reducing actions.

Providing future reference to aid in analysing field concerns.

Aiding in the initial design for manufacturing and assembly requirements.

Aiding in the objective evaluation of design requirements and design alternatives.

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System :Sub-System :

Component :

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Core Team :

Design Responsibility

Key Date

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FMEA Date (Ori.): (Rev.)

Item /

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Potential Failure Mode

Potential Effect of Failure

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Potential Causes of Failure

Current Design Control

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ActionResponsibility & Target Date

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Action Results

FMEA Number :

1. FMEA NUMBER : Enter the FMEA document number, which may be used for tracking.

FAILURE MODE AND EFFECT ANALYSIS

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FMEA Number :FAILURE MODE AND EFFECT ANALYSIS

2. System, Subsystem or component Name & number : Indicate the appropriate level of analysis and enter the name and number of the system, subsystem or component being analysed.

Action Results

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3. Design Responsibility : Enter the OEM, Department and group. Also include the supplier name if known.

Action Results

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4. Prepared By : Enter the OEM, Department and group. Also include the supplier name if known.

Action Results

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5. Model : Enter the intended model and vehicle line that will utilize and/or affected by the design release date.

Action Results

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Component :

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6. Key Date : Enter the initial FMEA due date which should not exceed the scheduled production design release date.

Action Results

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7. FMEA Date : Enter the date the original FMEA was compiled and the latest revision date.

Action Results

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8. Core Team : List the names of the responsible individuals and Departments which have the authority

Action Results

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9. Item/Function : Enter the name and item being analysed and show the design level as indicated on drawing. Enter the function of the item to meet design intent. Include environment issues (e.g.Temp., pressure, humidity etc.) If the item has more than one function with different potential modes of failure, list all the functions separately.

Action Results

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Component :

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10. Potential Failure Mode : Identify and list the each failure that could potentially fail to meet the design intent. A recommended starting point is a review of past things gone wrong, concern reports and group brainstorming.

Action Results

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Component :

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11. Potential Effect of Failure Mode : Identify the effect of the failure mode on the function as perceived by the customer. It is stated in terms of the specific system, subsystem or component being alanysed.

Action Results

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Component :

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12. Severity (S) : It is an assessment of the seriousness of the effect of the potential failure mode to the next component, system, subsystem or customer. Severity applies to the effect only. A reduction in severity ranking index can be affected only through a design change. It could be estimated on a “1” to “10” scale.

Action Results

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EffectHazardou

s without warning

Criteria : Severity of Effect

Rank

10Very high severity ranking when a potential failure affects safe vehicle operation and/or involves noncompliance with government regulation without warningHazardous

with warning

Very high severity ranking when a potential failure affects safe vehicle operation and/or involves noncompliance with government regulation with warningVery High Vehicle/item inoperable with loss of primary function

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High Vehicle/item operable but at reduced level of performance, customer dissatisfied

ModerateVehicle/item inoperable but comfort/convenience item(s) inoperable. Customer experiences discomfortLow

Fit & finish/squeak & rattle item does not conform. Defect noticed by most customers.

Vehicle/item inoperable but comfort/convenience item(s) operable at reduced level of performance. Customer experiences some dissatisfaction

Very low

Fit & finish/squeak & rattle item does not conform. Defect noticed by average customers.

Minor

Fit & finish/squeak & rattle item does not conform. Defect noticed by discriminating customers.

Very Minor

None No effect

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SUGGESTED EVALUATION CRITERIA FOR SEVERITY

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Component :

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13. Classification : Classify any special product characteristics (e.g.critical, key major, significant) for components, subsystem, system that may require additional process controls. Each item identified here in Design FMEA should have the special process controls identified in the Process FMEA.

Action Results

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Component :

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14. Potential causes of failure : It is an indication of a design weakness, the consequences of which is the failure mode. The cause should be listed so that remedial efforts can be aimed at pertinent causes.

Action Results

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Component :

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15. Occurrence (O) : It is the likelihood that a specific cause will occur. The occurrence rank has a meaning rather than value. Design change is the only way to reduce the ranking. It could be estimated on a “1” to “10” scale. The occurrence ranking number is related to the rating scale and does not reflect the actual likelihood of occurrence.

Action Results

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SUGGESTED EVALUATION CRITERIA FOR OCCURRENCE

Probability of Failure

Possible Failure Rates

Rank

10

9

8

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2

1

Very High : Failure is almost inevitable.

High : Repeated failures

Moderate : Occasional failure

Low : Relatively few failures

Remote : Failure is unlikely

1 in 2 1 in 3 1 in 8 1 in 20

1 in 80

1 in 400

1 in 2,000

1 in 15,000

1 in 150,000

1 in 1,500,000

>

<

CpK

>1.67

>1.50

>1.33

>1.17

>1.00

>0.83

>0.67

>0.51

>0.33

< 0.33

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Component :

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16. Current Design Control : List the prevention, design validation/verification (which will assure the design adequacy for the failure and cause under consideration. There are 3 types of design controls : 1) Prevent the cause or failure mode effect from occurring or reduce 2) Detect the cause and lead to corrective action and 3) Detect the failure mode.

Action Results

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Component :

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17. Detection : It is an assessment of the ability of the proposed type (2) current design control, to detect a potential cause or the ability of the proposed type (3) current design controls to detect the subsequent failure mode before the component, system, subsystem is released for production.

Action Results

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DetectionAbsolute Uncertainty

Criteria : Likelihood of detection by Design Control

Rank

10Design control will nor and/or can not detect a potential cause and subsequent failure mode or there is no Design control.

Very Remote

Very remote chance the design control will detect a potential and subsequent failure mode. 9

Very Low

Moderate

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SUGGESTED EVALUATION CRITERIA FOR DETECTION

Remote

Remote chance the design control will detect a potential and subsequent failure mode.Very low chance the design control will detect a potential and subsequent failure mode.

Low Low chance the design control will detect a potential and subsequent failure mode.Moderate chance the design control will detect a potential and subsequent failure mode.

Moderately High

Moderately high chance the design control will detect a potential and subsequent failure mode.

HighHigh chance the design control will detect a potential and subsequent failure mode.

Very High

Very High chance the design control will detect a potential and subsequent failure mode.

Almost certain

Design control will almost certainly detect a potential and subsequent failure mode.

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Component :

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18. Risk Priority Number (R.P.N.) : The RPN is the product of the severity (S), Occurrence (O) and Detection (D) ranking. RPN = (S) X (O) X (D). It is the majority of design risk. This value should be used to rank order the concerns in design. The RPN will be between “1” to “1000”. For higher RPN corrective action must be taken.

Action Results

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19. Recommended Action(s) : Corrected action should be first directed at the highest ranked concerns and critical items to reduce occurrence, severity and/or detection rankings.

Action Results

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20. Responsibility : Enter the organization and individual responsibility for the recommended action and the target completion date

Action Results

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21. Action(s) Taken : After an action has been implemented, enter a brief description of the actual action and effective date.

Action Results

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22. Resulting RPN : After the corrective action have been identified, estimate and record the resulting severity, occurrence and detection rankings to calculate resulting RPN. All resulting RPN(s) should be reviewed and further action is considered necessary. Repeat all the steps from 119 through 22

Action Results

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Failure Mode Effect Cause

Cannot generate Light

Dissatisfied customer Output from input mechanism missing

Failure Mode Effect Cause

Switch fails because of an open circuit

Dissatisfied customer Lighting system fails, Switch inoperative

Switch orientation tab dimensions not specified correctly

Failure Mode Effect CauseMold Temp.LowSwitch orientation tab

dimensions incorrect or tab missing

Dissatisfied customer Lighting system fails, Switch inoperative

Insufficient material injected into mold

System FMEA

Design FMEA

Process FMEA

System/Design/Process FMEA links

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DESIGN FMEA PROCESS FMEA

Design Goals

Reliability and quality goals

Preliminary Bill of Material

Preliminary list of special product/process characteristics

Management support

Characteristics matrix

Warranty information

Customer complaints/returns

Corrective/preventive actions

Process flow chart

System and/or Design FMEA

PFMEA of similar product/process

INPUT TO DEVELOP DESIGN & PROCESS FMEA

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ACTION AND PROCESS FMEA

Improve Detection This approach is typically desirable in short run only. It often reduce but does not eliminate defects.

Examples include product inspection systems like :

Successive Check System Operators inspect output from previous process prior to performing work. This is time consuming but promotes objectivitySelf Check System Each operators 100% inspects for defects prior to send parts to the next operation. This is less time consuming than other inspection systems but suffers judgement errors due to familiarity

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ACTION AND PROCESS FMEA Reduce or Eliminate Occurrence

This approach is more costly in short run only. It is more cost effective and desirable in the long runVarious approaches include :Product Redesign :Design the product so that the defect either cannot occur or is very unlikely to occur.Process Redesign :Design the process so that the defect either cannot occur or is very unlikely to occur. This involves such things as changes in tooling or the elimination or simplification of process stepsError proofing Inspection System :This rely on error to detect before it becomes defect. It reduces and not eliminate the occurrence.

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ACTION AND PROCESS FMEA Error Proofing Control Functions

Regulatory Control Methods :Stop the operation & prevent occurrence of serial defects.

Contact Methods :Detect abnormalities in a product’s shape or dimension by using sensing devices.Fixed Value Methods :This rely on error to detect before it becomes defect. It reduces and not eliminate the occurrence.

Regulatory Warning Methods :Alert the operator to a process abnormality by using a sensory device

Motion Step Methods :Detect abnormalities by checking for deviation in required motion.

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Variation

Materials Equipment

MethodsEnvironmentPeople

Metallurgy

Chemistry

Dimensions

Machine

Mtl.Hold

Fixture

Tooling

Teamwork

Communication

Training

Opn. Variation

HumidityLighting

Temperature

Cleanliness

Set-UpInstructions

Maintenance

Ergonomics

Input Teamwork Continual Improvement

Continual Improvement Loop

VARIATION AND CONTROL METHODS Understanding the causes of characteristic variation plays a vital role in guiding the team to correct method of control.

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Characteristic Variation

Process Flow

Product & Process Characteristic

Characteristic Importance

Control Methods

Voice of the Customer

Voice of the Process

DETERMINING IMPORTANCE LEVEL

When evaluating characteristics it is necessary to consider both …the “ Voice of the Customer” as well as

the “ Voice of the Process”

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RELIABILITY FMEAIt can be used as an effective tool in Total Productive Maintenance The goal of TPM is to maximize output and to work to zero downtime.TPM accomplishes its goal by eliminating losses common in Mfg. It mobilize the work force with the attitude that `equipment effectiveness’ is everyone’s responsibility.

For each operation failure mode is related to six losses :Equipment failureSetup and adjustmentIdling and minor stoppagesReduced speedProcess defectsReduced yield (from start-up to stable production)

For each failure mode team then lists….The effect of the failure to the department, plant or the customerThe cause for each failureThe current controls to manage the loss.If severity, occurrence and detection ratings are used, a consensus must be reached on the rating scales for each category before losses can be rated.,Develop rating scales for reliability FMEA

FMEA METHODOLOGY.ppt

Documents

action results

severity occurrence

suggested

design responsibilitykey

high severity

potential

design change

target date