FAILURE MODE AND EFFECT ANALYSIS

2012/13 FMEA Definitions • FMEA is a methodology to evaluate failure modes and their effects in designs and in processes. • FMEA is an analytical tec...
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2012/13

FMEA Definitions • FMEA is a methodology to evaluate failure modes and their effects in designs and in processes. • FMEA is an analytical technique that goes in for combining Technology and Experience of people to identify foreseen failures in a product or process and planning to eliminate the Failure. • FMEA is a group of activities to understand and evaluate potential failure of product or process and its effects, and identify actions that eliminate or reduce the potential failures.

FAILURE MODE AND EFFECT ANALYSIS Anna Dobrowolska

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FMEA – The way in which the component, subassembly, product, input, or process could fail to perform its intended function • Failure modes may be the result of upstream operations or may cause downstream operations to fail

– Things that could go wrong

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History of FMEA

• What is a FAILURE MODE?

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• First used in the 1960’s in the Aerospace industry during the Apollo missions • In 1974, the Navy developed MIL-STD-1629 regarding the use of FMEA • In the late 1970’s, the automotive industry was driven by liability costs to use FMEA • Later, the automotive industry saw the advantages of using this tool to reduce risks related to poor quality

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Types of FMEA

DESIGN FMEA

Major Classification • Design FMEA • Process FMEA



Sub Classification • Equipment FMEA • Maintenance FMEA • Service FMEA • System FMEA



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PROCESS FMEA

It is use in the design process by identifying known and foreseeable failures modes and ranking failures according to their impact on the product. Analyzes product design before release to production, with a focus on product function Analyzes systems and subsystems in early concept and design stages Quality Management

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PROCESS FMEA • Allows to identify areas of our process that most impact our customers

It is used to identify potential process failure modes by ranking failures and establishing priorities, and its impact on the internal or external customers.

• Helps identify how our process is most likely to fail • Points to process failures that are most difficult to detect

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PROCESS FMEA

FMEA: A Team Tool • A team approach is necessary.

– Methodology that facilitates process improvement – Identifies and eliminates concerns early in the development of a process or design – Improve internal and external customer satisfaction – Focuses on prevention – FMEA may be a customer requirement – FMEA may be required by an applicable Quality System Standard Quality Management

–familiar with FMEA

• The following should be considered for team members: • • • • • • 9

FMEA Inputs and Outputs

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Benefits of FMEA

Inputs

Outputs

Brainstorming C&E Matrix Process Map Process History Procedures Knowledge Experience

List of actions to prevent causes or detect failure modes

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Design Engineers Engineers Materials Suppliers Customers Suppliers Operators

FMEA

History of actions taken

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• FMEA is one of the most important tools of reliability analysis. • If undertaken early enough in the design process by senior level personnel it can have a tremendous impact on removing causes for failures or of developing systems that can mitigate the effects of failures. • It provides detailed insight into the systems interrelationships and potentials for failure. Quality Management

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FMEA Process Procedure

FMEA Procedure (Cont.)

1. Identify all components (task/operation) of process.

9. Calculate the Risk Priority Number (RPN)

2. For each task of process determine the failure modes

10. -11. Develop recommended actions, assign responsible persons, and take actions and time to finish action

3. For each failure mode, determine effects

– Give priority to high RPNs – MUST look at severities rated a 10

4. Select a severity level for each effect 5. Identify potential causes of each failure mode

12. -16. Assign the action taken and severity, occurrence, and detection levels and compare RPNs.

6. Select an occurrence level for each cause 7. List current controls for each cause 8. Select a detection level for each cause

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Step 2. For each task of process determine the failure modes

Step 1. Identify all components (task/operation) of process.

• Failure mode: • You can use process map

– The way in which the component, subassembly, product, input, or process could fail to perform its intended function • Failure modes may be the result of upstream operations or may cause downstream operations to fail

– Things that could go wrong

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Step 3-4. For each failure mode, determine effects and select a severity level for each effect

• Often can’t do anything about this

• Severity level: Rating Scales from 1 to 10: – 1: non effect – 10: maximum severity

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Severity Ranking

• Effects on internal and external customers (eg another processes and final clients) • Severity – Importance of the effect on customer requirements

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Effect

Rank

None

1

Example of Criteria No effect

Very Slight

2

Negligible effect on Performance. Some users may notice.

Slight

3

Slight effect on performance. Non vital faults will be noticed by many users

Minor

4

Minor effect on performance. User is slightly dissatisfied.

Moderate

5

Reduced performance with gradual performance degradation. User dissatisfied.

Severe

6

Degraded performance, but safe and usable. User dissatisfied.

High Severity

7

Very poor performance. Very dissatisfied user.

Very High Severity

8

Inoperable but safe.

Extreme Severity

9

Probable failure with hazardous effects. Compliance with regulation is unlikely.

Maximum Severity

10

Unpredictable failure with hazardous effects almost certain. Non-compliant with regulations. Quality Management

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Step 5-6. Identify potential causes of each failure mode and select an occurrence level for each cause

Failure Modes and Effects • The relationship between failure modes and effects is not always 1 to 1.

• You can use the Causes and Effect Diagram Failure Mode 1

Effect 1

Failure Mode 2

Effect 2

• Occurrence – Frequency with which a given cause occurs and creates failure modes

•Occurrence level: Rating Scales from 1 to 10:

Failure Mode 1 Effect 1

– 1: extremely unlikely – 10: maximum severity.

Failure Mode 2 Effect 1 Failure Mode 1 Quality Management

Effect 2

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Step 7-8. List current controls for each cause and select a detection level for each cause

Occurrence Ranking Occurrence

Rank

Extremely Unlikely

1

Example of criteria Less than 0.01 per thousand

Remote Likelihood

2

≈0.1 per thousand rate of occurrence

Very Low Likelihood

3

≈0.5 per thousand rate of occurrence

Low Likelihood

4

≈1 per thousand rate of occurrence

Moderately Low Likelihood

5

≈2 per thousand rate of occurrence

• Detection – The ability of the current control scheme to detect or prevent a given cause

Medium Likelihood

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≈5 per thousand rate of occurrence

•Detection level: Rating Scales from 1 to 10:

Moderately High Likelihood

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≈10 per thousand rate of occurrence

Very High Severity

8

≈20 per thousand rate of occurrence

Extreme Severity

9

≈50 per thousand rate of occurrence

Maximum Severity

10

≈100 per thousand rate of occurrence Quality Management

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– 1: extremely likely – 10: extremely unlikely .

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Detection Ranking

Rating Scales - summary

Detection

Rank

Example of Criteria

Extremely Likely

1

Can be corrected prior to prototype/ Controls will almost certainly detect

Very High Likelihood

2

Can be corrected prior to design release/Very High probability of detection

High Likelihood

3

Likely to be corrected/High probability of detection

Moderately High Likelihood

4

Design controls are moderately effective

Medium Likelihood

5

Design controls have an even chance of working

Moderately Low Likelihood

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Design controls may miss the problem

Low Likelihood

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Design controls are likely to miss the problem

Very Low Likelihood

8

Design controls have a poor chance of detection

Remote Likelihood

9

Unproven, unreliable design/poor chance for detection

Extremely Unlikely

10

No design technique available/Controls will not detect

• Occurrence • Detection – 1 = Likely to Detect, 10 = Not Likely to Detect

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RPN is the product of the severity, occurrence, and detection scores.

Occurrence

X

Detection

=

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• Give priority to high RPNs • MUST look at severities rated a 10 RPN

• Recommended actions must remove the causes:

No cause

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Step 10- 11. Develop recommended actions, assign responsible persons, and time to finish action

Step 9. Calculate the Risk Priority Number (RPN)

X

– 1 = Not Severe, 10 = Very Severe – 1 = Not Likely, 10 = Very Likely

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Severity

• Severity

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No failure

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No effect

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Step 12-16. Assign the action taken and severity, occurrence, and detection levels and compare RPNs.

FMEA Example Track stop  FMEA for improving customer satisfaction with the coffee served at the truck stop

• After finished actions

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STEP 1. Identify all task/operation of process. START

Place Filter in Maker

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START

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STEP 2. For each task of process determine the failure modes

Place Filter in Maker Offer Cream & Sugar

STOP 1

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1

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„Fill carafe with water” List of failure mode

Step 2. For each task of process determine the failure modes Process Potential Potential S Step/ Input Failures Mode Failures Effects

Wrong amount with water Water too warm Carafe not clean

1

2

3

4

Potential O Causes 5

6

Current Controls 7

D RPN 8

4

Potential O Causes 5

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9

6

Current Controls 7

D RPN 8

9

Actions Recomended

RESP./ TIME

Actions taken

10

11

12

S O D RPN 13 14 15

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Step 3-4 For each failure mode, determine effects and select a severity level for each effect 1

3

16

Fill carafe Wrong amount with water of water

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Process Potential Potential S Step/ Input Failures Mode Failures Effects

2

Actions Recomended

RESP./ TIME

Actions taken

10

11

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Step 4-5 Identify potential causes of each failure mode and select an occurrence level for each cause

S O D RPN 13 14 15

16

Fill carafe Wrong amount Coffee too with water of water strong or week 8

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Process Potential Potential S Step/ Input Failures Mode Failures Effects 1

2

3

4

Potential O Causes 5

6

Current Controls 7

D RPN 8

9

Actions Recomended

RESP./ TIME

Actions taken

10

11

12

S O D RPN 13 14 15

16

Fadded level Fill carafe Wrong amount Coffee too marks of with water of water strong or week 8 carafe 4 Water spilled from 8 carafe 5

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Step 7-8 List current controls for each cause and select a detection level for each cause Process Potential Potential S Step/ Input Failures Mode Failures Effects 1

2

3

4

Potential O Causes 5

Current Controls

6

7

Fadded level Fill carafe Wrong amount Coffee too Visual marks of with water of water strong or week 8 carafe 4 inspection Water spilled from 8 carafe 5 None

D RPN 8

9

Actions Recomended

RESP./ TIME

Actions taken

10

11

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Step 9. Calculate the Risk Priority Number (RPN)

S O D RPN 13 14 15

16

4

Process Potential Potential S Step/ Input Failures Mode Failures Effects 1

2

3

4

Potential O Causes 5

Current Controls

6

7

Fadded level Fill carafe Wrong amount Coffee too marks of Visual with water of water strong or week 8 carafe 4 inspection Water 8 spilled from 5 None

D RPN 8

9

Actions Recomended

RESP./ TIME

Actions taken

10

11

12

S O D RPN 13 14 15

16

4 128 9 360

9

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STEP 2-9 – next Failure Mode

STEP 2-9 – next Failure Mode START

Process Potential Potential S Step/ Input Failures Mode Failures Effects 1

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Potential O Causes 5

Fadded level Fill carafe Wrong amount Coffee too marks of with water of water strong or week 8 carafe Water spilled from 8 carafe Fauced not Water too Coffee too allowed to warm strong 8 run and cool Employee not aware of need for cool 8 water

Place Filter in Maker

1

2

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Current Controls

6

7

D RPN 8

9

Visual 4 inspection

4

128

5 None

9

360

8 Finger

8

512

7 None

10

560

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Actions Recomended

RESP./ TIME

Actions taken

10

11

12

S O D RPN 13 14 15

16

40

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STEP 2-9 – next Failure Mode 2

3

4

5

6

7

Fadded level Fill carafe Wrong amount Coffee too Visual marks of with water of water strong or week 8 carafe 4 inspection Water spilled from 8 carafe 5 None Water too warm

Carafe not clean

Coffee too strong

Foregin objects in coffee

Bad taste

Fauced not allowed to 8 Employee run and cool 8 Finger not aware of need for cool 8 water 7 None Carafe not 10 washed Carafe stored 10 improperly

8

9

4

128

10

11

12

Step 10-11

16

Process Potential Potential S Step/ Input Failures Mode Failures Effects 1

9

360

8

512

10

Fill carafe with water

2

3

4

160

7 Training

5

350

4

Potential O Causes 5

Current Controls

6

7

RESP./ TIME

Actions taken

10

11

12

4

128 Replace carafe

5 None

9

Anna 360 Train employees 31.12.12

8 Finger

8

Anna 512 Train employees 31.12.12

7 None

10

Anna 560 Train employees 31.12.12

Visual 4 inspection

4

Appoint inspector Fred 160 before storage 15.12.12

7 Training

5

350 Create storage bin

Water too warm Coffee too strong

Water spilled 8 from carafe Fauced not allowed to run 8 and cool

Foregin objects in Carafe not Carafe not clean coffee 10 washed Carafe stored Bad taste 10 improperly

Actions Recomended

9

Fadded level Visual 8 marks of carafe 4 inspection

Employee not aware of need 8 for cool water

D RPN 8

Wrong amount of Coffee too strong water or week

560

Visual 4 inspection

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START

13 14 15

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Step 12-16. Assign the action taken and severity, occurrence, and detection levels and compare RPNs

STEP 2-9. Next task /operation 1

Fill carafe with water

Place Filter in Maker

2

3

4

Potential O Causes 5

Current Controls

6

7

Wrong amount of Coffee too strong water or week

Fadded level Visual 8 marks of carafe 4 inspection

Water too warm Coffee too strong

Water spilled 8 from carafe Fauced not allowed to run 8 and cool

Employee not aware of need 8 for cool water Foregin objects in Carafe not Carafe not clean coffee 10 washed Carafe stored Bad taste 10 improperly

D RPN 8

9

Actions Recomended

RESP./ TIME

Actions taken

10

11

12

13 14 15

Carafe replaced

Mel 31.12.12

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S O D RPN 16

4

128 Replace carafe

8 1 3

24

5 None

9

Anna 360 Train employees 31.12.12

Employees trained

8 2 7

112

8 Finger

8

Anna 512 Train employees 31.12.12

Employees trained

8 2 6

96

4

Anna 560 Train employees 31.12.12 Appoint inspector Fred 160 before storage 15.12.12

5

350 Create storage bin

Employees trained Andy is new inspector New storage bin in place Employees trained

7 None Visual 4 inspection 7 Training

10

Anna Train employees 31.12.12 Quality Management

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Mel 31.12.12

Anna Train employees 31.12.12

Process Potential Potential S Step/ Input Failures Mode Failures Effects

1

S O D RPN 13 14 15

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64

10 1 4

40

10 2 3

60

10 2 3

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Key Points

Summary • An FMEA: – Identifies the ways in which a product or process can fail – Estimates the risk associated with specific causes – Prioritizes the actions that should be taken to reduce risk

• FMEA is a team tool • There are two different types of FMEAs: – Design – Process

• Inputs to the FMEA include several other quality tools: – Ishikawa diagram – Process map Quality Management

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