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Module-12
Copyright 2012 BSI. All rights reserved.
Module-12Failure Modes and Effects Analysis (FMEA)
Failure Mode and Effects Analysis Learning Objectives
At the end of this section delegates will be able to:
Understand the role of Failure Mode and Effects Analysis, FMEA within the DMAIC Improvement
Process
Conduct a Process FMEA on an existing, new or modified transactional process
Copyright 2012 BSI. All rights reserved.
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Use the Process FMEA to prioritise areas for attention
Use the Process FMEA to support the generation of Control Plans
Failure Mode and Effects Analysis - Agenda
Introduction to Failure Mode and Effects Analysis
FMEA Within DMAIC
FMEA Roadmap
FMEA Form and Control Plans
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Implementing FMEA
Summary
Classic Failures
City trader buys 15,000,000 shares instead of 15,000
Leap day shuts down bank cash machines
NASA probe lost due to Metric/Imperial units confusion
Worldwide Perrier stocks withdrawn due to filter failure
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Pilot shuts down wrong aircraft engine
Company emails confidential account information to analysts and has to suspend trading
Introduction to FMEA
Failure Mode and Effects Analysis, FMEA is:
A systematic method of identifying and investigating potential design or process weaknesses.
A means to evaluate and manage product risks.
A means of evolving organizational knowledge.
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Developed in the aerospace industry in the mid 1960s
Also sometimes referred to as Failure Mode Effect and Criticality Analysis, FMECA
FMEA Purpose
Purpose:
Recognise and evaluate the potential failure modes and causes associated with the design and
manufacture of a product or design and operation of any process.
Identify actions which could eliminate or reduce the chance of the potential failure occurring.
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Document the analysis and changes made.
Application of FMEA in Six Sigma
In Design for Six Sigma - (Design FMEA) :
to identify potential failure modes
to identify potential causes of failure
to eliminate/minimise the potential failure modes within the Design process
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In Transactional/Operational Six Sigma (Process FMEA) :
to analyse the existing processes (identify possible xs)
to improve the process (elimination/reduction of failure modes)
to select new process alternatives
to develop control plans
Define Measures (ys)
Check Data Integrity
Determine Process
Control Critical xs
Monitor ys1 5 10 15 20
10.2
10.0
9.8
9.6
Upper Control Limit
Lower Control Limit
Develop Detailed Process Maps
Identify Critical Process Steps (xs) by looking for:
START
PROCESSSTEPS
DECISION
STOP
Brainstorm Potential Improvement Strategies
Select Improvement Strategy
Criteria A B C DTime + s - +Cost + - + sService - + - +Etc s s - +
Analyse Improve ControlMeasureDefine Select Project Define Project
Objective Form the Team
Map the Process
Define
Six Sigma Transactional Improvement Process
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15 20 25 30 35
LSL USL
Determine Process Stability
Determine Process Capability
Set Targets for Measures
Phase Review
Validate Control Plan
Identify further opportunities
Close Project
y
Phase Review
by looking for: Process Bottlenecks Rework / Repetition Non-value Added
Steps Sources of Error /
Mistake Map the Ideal
Process Identify gaps
between current and ideal
Phase Review
Plan and Implement Pilot
Verify Improvement
Implement Countermeasures
15 20 25 30 35
LSL USL
Phase Review
Map the Process Identify Customer
Requirements
Identify Priorities Update Project File
Phase Review
Application of PFMEA in DMAIC
Analyse:
To analyse the existing processes and identify possible xs (causes of failure)
Improve:
To improve the process (elimination/reduction of failure modes)
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To select new process alternatives
Control:
To develop control plans
It is only necessary to conduct PFMEA on the modified/changed areas of the process
Process FMEA Roadmap
1.Describe Process 2.Define
Functions
3.Identify Potential Failure Modes8.Take Action
9.Assess Results
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Failure Modes
4.Describe Effects of Failure
5.Determine Causes
6.Current Controls
7.Calculate Risk
Action
Step 1: Describe Process
Process Flow Diagrams Error & Correction Data Process
1.Describe Process
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Error & Correction Data Internal Problem Data Customer Feedback
Process Knowledge
Suppliers:SalesStores
Outputs:Packaged ProductShipping requisition
Step 1: Describe Process- Order Fulfilment
Receive order
Check stock
Pull product and check
All available?
Order stock
Notify Sales
Yes
No
1.Describe Process
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SalesStores
Inputs:OrderProductPackaging
Customers:Sales
ShippingEnd customer
Shipping requisitionOrder fulfilment note
Pull product and check
Package product
Weigh product
Correct weight?
Transfer to Goods OutYes
No
List of Functions(Purposes)
Step 2: Define Function
2.Define Functions
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ProcessFlow
Diagram
Action Verb Noun
Publish Report
Action Verb NounProcess Information
Examples of Functions
2.Define Functions
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Gather
Approve
Release
Project
Credit
Product
Data
Sales
Test Part
Check
Contact
Receive
Deliver
Calculate
Address
Customer
Stock
Order
Price
Step 2: Define Function
Functions
Receive order
Check sufficient stock
2.Define Functions
Receive order
Check stock Order stock
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Check sufficient stock
Notify sales
Order stock
Pull product
Check product
Etc.
Pull product and check
All available? Notify Sales
Yes
No
List of PotentialFailures
Does not/CannotToo muchToo little
Step 3: Identify Potential Failure Modes
3.Identify Potential Failure Modes
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Function Does Not Function?
Too littleToo early Too lateDegradedIntermittentIncorrectUnwanted
Function
Process Function Potential Failure Modes
Receive Order Does not receive orderReceives incorrect orderReceives too many orders
Check sufficient stock Does not check sufficient stock
Step 3: Identify Potential Failure Modes
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Check sufficient stock Does not check sufficient stockIncorrect check (wrong conclusion)
-Insufficient stock when sufficient-Sufficient stock when insufficient
Notify Sales Does not notify salesNotifies sales too lateNotifies sales with incorrect information
Assume the failure could occur
- what would be the effect ?
Consider :
How it affects the process (processor):
next operation
Step 4: Describe Effects of Failure
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next operation
subsequent downstream operations
How it affects the end user (customer).
Immediate & delayed impact.
Be realistic.Note: There may be several potential effects for each failure, but these are listed together as one overall effect.
4.Describe Effects of Failure
Does not Receive Order
Step 4: Describe Effects of Failure
4.Describe Effects of Failure
Assume the failure could occur
- what would be the effect?
Potential Failure Modes Potential Effects
Order not fulfilled, customer has to re-submit order
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Incorrect stock check (Concludes insufficient when sufficient available)
Delay in fulfilling order, excess stock, possible loss of order
Incorrect stock check (Concludes sufficient stock when insufficient available)
Incomplete order, delay, customer dissatisfaction
Notify Sales too late Customer not aware of delay, sales takes further orders
What could cause the potential failure mode to occur ?
Step 5: Determine Causes
Process / processor errors that could lead to the failure
Be specific, processor error or equipment failure are too vague
Consider the working environment of the process, condition of equipment, IT systems
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Consider the working environment of the process, condition of equipment, IT systems
There will typically be several causes for each failure mode
Identify root causes for severe failures
5.Determine Causes
Step 5: Determine Causes
What could cause the potential failure mode to occur ?
Potential CausesPotential Failure Modes
5.Determine Causes
Incorrectly addressed
Delivered to wrong department
Does not receive order
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Delivered to wrong department
Lost in post
Incorrect stock check Error in inventory levels
Entered wrong part code
Entered wrong quantity
Multiple orders in process
Process FMEA Roadmap
1.Describe Process 2.Define
Functions
3.Identify Potential Failure Modes
8.Take Action
9.Assess Results
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3.Identify Potential Failure Modes
4.Describe Effects of Failure
5.Determine Causes
6.Current Controls
7.Calculate Risk
Action
Workshop 1:Identify Potential Failures Modes
For the given example, describe the process using a process flowchart. Describe each process step in terms of its function using a verb noun combination e.g. check stock, calculate profit , complete invoice, check form etc. (N.B. depending on the detail of the flowchart there may be more than one function at each step).
Working from the process flowchart, identify potential failure modes by adding the key words: does not/cannot/incorrect function, too much/too little function, too early/late function etc. Each function should have at least one failure mode.
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Each function should have at least one failure mode.
For each of the failure modes identify the potential effects of the failure on the process, processor and/or the customer. If there are several effects then group these together as the overall effect for the failure mode. Each failure mode should have one effect.
For each failure mode, identify the possible causes of the failure. Be specific, processor error" is too vague. There will typically be more than one cause per failure mode.
Prepare a short presentation on your team's findings.
Workshop 1
Time:
Process FMEA Roadmap
1.Describe Process 2.Define
Functions
3.Identify Potential Failure Modes
8.Take Action
9.Assess Results
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Failure Modes
4.Describe Effects of Failure
5.Determine Causes
6.Current Controls
7.Calculate Risk
Action
In order of preference there are three types of current
controls :
1. Prevent the cause
2. Detect the cause, leading to corrective action
3. Detect the failure (defect)
Identify the current controls to prevent / detect the failure before it reaches the customer
Step 6: Current Controls
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3. Detect the failure (defect)
These might include:
Control Charts
Check Sheets
Mistake Proofing
Training
Information Technology
6.Current Controls
Step 6: Current Controls
Error in inventory levels
Potential Causes Current Controls
Potential Failure Modes
Identify the current controls to prevent / detect the failure before it reaches the customer
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Incorrect stock check Error in inventory levels
Entered wrong part code
Entered wrong quantity
Multiple orders in process
Stock take (annual), Stock control system
Double entry required
No controls6.Current Controls
Double entry required
Severity ofProbability
ofDetection Risk
Step 7: Calculate Risk
7.Calculate Risk
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Severity ofthe Effect
Probabilityof
Occurrence
Detection(Capability of
Current Controls)
RiskPriorityNumber
X X =
Process FMEA Severity Rating
How serious is the effect ?
Sev Effect Customer Effect Processor Effect
5 Hazardous Safety compromised or non-compliance with legal issue
May endanger processor or process equipment
4 High Loss of service Process stops, 100% transactions incorrect
3 Moderate Very dissatisfied, service provided Significant process disruption, many
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Note : Many organisations choose to modify the descriptions to best describe their industry.
3 Moderate Very dissatisfied, service provided but much degraded
Significant process disruption, many transactions require correcting
2 Low Inconvenient, service provided but not up to expectations
Some process disruption, some transactions require reworking
1 Very minor/none
Not noticed by most customers Minor disruption to process or no effect
Process FMEA Occurrence Rating
How likely is the cause ?
Occ Probability Likely failure rates
5 Very high, persistent failures 1 in 10 transactions (opportunities)
4 High, frequent failures 1 in 100 transactions (opportunities)
3 Moderate, occasional failures 1 in 1,000 transactions (opportunities)
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Note : Many organisations choose to modify the descriptions to best describe their industry.
3 Moderate, occasional failures 1 in 1,000 transactions (opportunities)
2 Low, relatively few failures 1 in 10,000 transactions (opportunities)
1 Remote, failure is unlikely 1 in 100,000 transactions (opportunities)
Process FMEA Detection Rating
How effective are the Current Controls?
Det Criteria Typical Detection/Control Method Type
5 No Controls Cannot detect or is not checked ?
4 Controls detect failure Inspection, checking 3
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4 Controls detect failure Inspection, checking 3
3 Controls detect cause Control charts (focused on outputs) 3/2
2 Controls prevent failure Control charts (focused on inputs) 2/1
1 Controls prevent cause Mistake Proofing, training 1
Effect Incomplete order, delay, customer dissatisfaction
Severity = 3
Step 7: Calculate Risk
Failure ModeIncorrect Stock Check
7.Calculate Risk
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Cause Multiple orders in process
Current Controls No Controls
Occurrence = 3
Detection = 5
RPN = 3 x 3 x 5 = 45
Corrective Action Effects On RPN Rating
Step 8: Take Action
Corrective Action Severity Occurrence Detection 1. Process change Maybe Yes Yes
8.Take Action
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Note : Do not modify RPN until corrective action is completed (Step 9)
1. Process change Maybe Yes Yes 2. Improve Current Control No Maybe Yes 3. Improve Employee training No Yes Yes 4. Mistake proofing No Yes Yes 5. Increased inspection No No Maybe
Step 8: Take Action
8.Take Action
Effect Incomplete order, delay, customerdissatisfaction
Severity = 3
Failure ModeIncorrect Stock Check
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Stock is temporarily reserved against enquiry
RPN = 3 x 3 x 5 = 45
Cause Multiple orders in process
Current Controls No Controls
Occurrence = 3
Detection = 5
Review corrective actions and modify RPN figure based on results.
Before Improvement
R
e
d
u
c
e
d
R
i
s
k
Step 9: Assess Results
9.Assess Results
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After Improvement
R
P
N
R
e
d
u
c
e
d
R
i
s
k
Step 9: Assess Results
8.Take Action
Effect Incomplete order, delay, customer dissatisfaction
Severity = 3
Failure ModeIncorrect Stock Check
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Stock is temporarily reserved against enquiry
RPN = 3 x 3 x 2 = 18
Cause Multiple orders in process
Current ControlsNo Controls
Occurrence = 3
Detection = 5 2x
Process FMEA Roadmap
1.Describe Process 2.Define
Functions
3.Identify Potential Failure Modes
8.Take Action
9.Assess Results
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Failure Modes
4.Describe Effects of Failure
5.Determine Causes
6.Current Controls
7.Calculate Risk
Action
FMEA Purpose
Purpose:
Recognise and evaluate the potential failure modes and causes associated with the design and
manufacture of a product or any process.
Identify actions which could eliminate or reduce the chance of the potential failure occurring.
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Document the analysis and changes made.
FMEA Form
FAILURE MODE & EFFECTS ANALYSIS PROCESS FMEA
Product: PROCESS FMEA No. Page : of Application: Issue No. Originators: Customer: Date:
ITEM PROCESS POTENTIAL POTENTIAL POTENTIAL CURRENT RECOMMENDED RESP. ACTION RESULTS FUNCTION FAILURE MODE EFFECTS OF
FAILURE SEV CAUSE(S) OF FAILURE OCC CONTROLS DET RPN ACTIONS FOR
ACTION ACTIONS TAKEN
SEV OCC DET RPN
3 Checks sufficient stock
Incorrect Stock Check (Concludes sufficient
stock when insufficient available)
Incomplete order, delay,
customer dissatisfacti
on
3 Multiple orders in process 3 No controls 5 45 Stock reserved against enquiry
SCB 18.08.03 3 3 2 18
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FMEA Form
ITEM PROCESS POTENTIAL POTENTIAL POTENTIAL FUNCTION FAILURE MODE EFFECTS OF
FAILURE SEV CAUSE(S) OF FAILURE OCC
3 Checks sufficient stock
Incorrect Stock Check (Concludes sufficient
stock when insufficient available)
Incomplete order, delay,
customer dissatisfacti
on
3 Multiple orders in process 3
Expand detail in Control Plan
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CURRENT RECOMMENDED RESP. ACTION RESULTS CONTROLS DET RPN ACTIONS FOR
ACTION ACTIONS TAKEN
SEV OCC DET RPN
No controls 5 45 Stock reserved against enquiry
SCB 18.08.03 3 3 2 18
Control Plan
Control Plan
Detail of the Current Controls are held in an additional form the Control Plan
Control Plan (and Current Controls) may need to change based on recommended actions
The effectiveness of the Control Plan is tested during the Control phase of DMAIC
All Critical xs should be included in the Control Plan
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Workshop 2: Risk Assessment
Transfer the failure modes, effects and causes identified in workshop 1 to the large FMEA form.
Using the Severity rating scale, rate each of the failure mode effects and record the number in the appropriate column. Where there are several possible effects for a failure mode, take the worst case for the rating. There should be only one severity rating for each failure mode.
Using the Occurrence rating scale and your team's expertise, rate each of the potential causes of failure and record the numbers in the appropriate column.
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For the purpose of the exercise, assume there are no Current Controls (Detection rating = 5), calculate the Risk Priority Numbers (RPN) and record on the chart. There should be one RPN score for each cause listed on the FMEA form.
For the top five RPN's, identify possible actions to reduce the RPN scores. Identify which of the categories (Severity, Occurrence, and Detection) would be reduced once the action has been completed.
Prepare a short presentation to summarise your team's findings.
Implementing FMEA
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Implementing FMEA
Who Should Do FMEA ?
Team not an individual
Cross functional opportunity to improve communication and understanding
Include the processors (people who work in the process)
Consider including the customer where appropriate
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10 Keys To FMEA Success
Support by top & middle management
Motivated team members
Cross functional representation on the team
Treat as before the event not after the fact
Generate company specific rating scales
Treat as a living document-reflect latest revisions
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Treat as a living document-reflect latest revisions
Execute recommended actions
Integration into your development process
Generate & use a library of generic FMEAs
Follow the spirit, not the form
Common Mistakes
Applied too late
Poor team working, wrong team members or no team
Over dependence upon the numbers
Inconsistency in numbers
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Solving all problems in meetings
When Do You Start PFMEA ?
Within Six Sigma DMAIC:
If there is a Process FMEA available this should be reviewed during the Measure/Analyse
phases. If there is no FMEA then consider completing one for the part of the process of
interest.
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During the Improve/Control phases a PFMEA should be updated/completed for the areas of
the process that have changed.
Improving Organisational Capability
SpecificFMEA
SpecificFMEA
GeneralFMEA
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KnowledgeBase
DesignCheck-list
Failure Mode and Effects Analysis
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Failure Mode and Effects Analysis Summary
Failure Mode and Effects Analysis Summary
Process Failure Mode and Effects Analysis, PFMEA, can be applied within the DMAIC
Improvement Process
A Process FMEA can be conducted on an existing, new or modified process
The Process FMEA prioritises areas for attention
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The Process FMEA prioritises areas for attention
The Process FMEA can be used to support the generation of Control Plans
Application of PFMEA in DMAIC
Analyse:
To analyse the existing processes and identify possible xs (causes of failure)
Improve:
To improve the process (elimination/reduction of failure modes)
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To improve the process (elimination/reduction of failure modes)
To select new process alternatives
Control
To develop control plans
It is only necessary to conduct PFMEA on the modified/changed areas of the process
Define Measures (ys)
Check Data Integrity
Determine Process
Control Critical xs
Monitor ys1 5 10 15 20
10.2
10.0
9.8
9.6
Upper Control Limit
Lower Control Limit
Develop Detailed Process Maps
Identify Critical Process Steps (xs) by looking for:
START
PROCESSSTEPS
DECISION
STOP
Brainstorm Potential Improvement Strategies
Select Improvement Strategy
Criteria A B C DTime + s - +Cost + - + sService - + - +Etc s s - +
Analyse Improve ControlMeasureDefine Select Project Define Project
Objective Form the Team
Map the Process
Define
Six Sigma Transactional Improvement Process
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51
15 20 25 30 35
LSL USL
Determine Process Stability
Determine Process Capability
Set Targets for Measures
Phase Review
Validate Control Plan
Identify further opportunities
Close Project
y
Phase Review
by looking for: Process Bottlenecks Rework / Repetition Non-value Added
Steps Sources of Error /
Mistake Map the Ideal
Process Identify gaps
between current and ideal
Phase Review
Plan and Implement Pilot
Verify Improvement
Implement Countermeasures
15 20 25 30 35
LSL USL
Phase Review
Map the Process Identify Customer
Requirements
Identify Priorities Update Project File
Phase Review