six sigma 10 improve phase-2
TRANSCRIPT
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Six Sigma ImprovePhase
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FMEA
Failure Mode Effects Analysis (FMEA) is an approach to: Identify potential failure for a product or a process Estimate risks that are associated with causes Determine actions to reduce risks Evaluate product design validation plan Evaluate process current control plan
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FMEA typesThere are two types:
Process: Focus on Process Inputs Design: Used to analyze product designs before they are
released to production
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The use of the FMEA
Improve processes before failure occur (Proactiveapproach)
Prioritize resources to ensure process improvement effortsare beneficial to customers
Track and document completion of projects It is a living document. It will be updated and reviewed all
the time
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Inputs & Outputs to FMEAFMEA is a top-down analysis that is, the analysis starts with a big
picture of all the functions required to perform the purpose of the system.Inputs
Process Map C&E Matrix Process History Process technical procedures
Outputs Actions list to prevent causes Actions list to detect failure modes
Document history of actions taken
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C&E MatrixThe C&E matrix provides the initial input to the FMEA andexperimentation. When each of the output variables (requirements) arenot correct, that represents potential "EFFECTS".
When each input variable is not correct, that represents "FailureModes". Determine how each selected input variable can "go wrong"and place that in the Failure Mode column of the FMEA.
Inputs & Outputs to FMEA
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FMEA step-by-step For each process input, determine the ways in which the input can
go wrong- the failure modes.
What is theprocess
step/input underinvestigation?
In what ways does theinput go wrong?
What is the impact onthe Output Variables
(CustomerRequirements)
or internalrequirements?
Howseveris theeffect tothe
customer?
What causes the inputto go wrong?
Howoftendoes causeof FM
occur?
ProcessStep/Input
Potential FailureMode
Potential FailureEffects Potential Causes
OCC
SEV
What can go wrong with input
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FMEA step-by-step For each failure mode associated with the inputs,
determine the effects of the failures on the customer.
What is theprocess
step/input underinvestigation?
In what ways does theinput go wrong?
What is the impact onthe Output Variables
(CustomerRequirements)
or internalrequirements?
Howsever
is theeffect tothe
customer?
What causes the inputto go wrong?
Howoftendoes causeof FM
occur?
Process
Step/Input
Potential Failure
Mode
Potential Failure
Effects Potential Causes
OC
C
SE
V
What the effect on outputs?
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FMEA step-by-step Identify potential causes of each failure mode.
What is theprocess
step/input underinvestigation?
In what ways does theinput go wrong?
What is the impact onthe Output Variables
(CustomerRequirements)
or internalrequirements?
Howseveris theeffect tothe
customer?
What causes the inputto go wrong?
Howoftendoes causeof FM
occur?
Process
Step/Input
Potential Failure
Mode
Potential Failure
Effects Potential Causes
OC
C
SE
V
What are the causes?
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FMEA step-by-step List the current controls for each cause or failure mode
(Prevent/Detect).How are theseFound or prevented?
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FMEA step-by-step
Create Severity, Occurrence, and Detection rating scales.
Severity of effect- importance of effect on customerrequirements. It is a safety and other risks if failure occurs.
1= Not Severe, 10= Very Severe
Occurrence of cause- frequency in which a give Cause occursand creates Failure Mode. Can sometimes refer to the frequencyof a failure mode.
1= Not Likely, 10= Very Likely
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FMEA step-by-step
Create severity, Occurrence, and Detection rating scales.
Detection- ability to: Prevent the causes or failure mode from occurring or reduce
their rate of occurrence Detect the cause and lead to corrective action Detect the failure mode 1= Likely to Detect, 10= Not Likely at all to Detect
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FMEA step-by-step
Risk Priority Number: After rating we get the output on an FMEA Risk
Priority Number. It is calculated as the product ofEffects, Causes, and Controls
RPN= Severity X Occurrence X Detection
EffectsCauses Controls
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FMEA step-by-stepDetermine recommended actions to reduce high RPNs:
Howwell canyoudetect
causeor FM?
What are theactions for
reducing theoccurrence of the
Cause, orimproving
detection? Should
have actions onlyon high RPNs or
easy fixes.
Who isresponsible for the
recommendedaction?
What are thecompleted actions
taken with therecalculated RPN?
Be sure toinclude
completion
month/year.
DET
RPN
SEV
OCCResponsible Actions Taken
RPN
ActionsRecommended
DET
What can be done?
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FMEA step-by-step Take appropriate actions and recalculate RPNs
Howwell canyoudetect
causeor FM?
What are theactions for
reducing theoccurrence of the
Cause, orimproving
detection? Should
have actions onlyon high RPNs or
easy fixes.
Who isresponsible for the
recommendedaction?
What are thecompleted actions
taken with therecalculated RPN?
Be sure toinclude
completion
month/year.
DET
RPN
SEV
OCCResponsible Actions Taken
RPN
ActionsRecommended
DET
Assign responsible Parties
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FMEA ExampleConsider the case of starting a car
basic system requirements electrical power to turn the engine fuel for the engine operation of the ignition system mechanical operation of the engine
each of these can be expanded to identify morespecific operations
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FMEA ExampleIdentify How Each May Fail
Electric power to turn engine Battery Dead
lights left on (human failure) old battery (mechanical failure) faulty battery (mechanical failure)
Battery connector corroded Cable broken or damaged Battery stolen
Fuel for engine Gas tank empty Fuel pump broken
Other
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FMEA ExampleIdentify the Effects of
Each Failure Examples
Dead battery, engine will notturn over
Battery connector corroded,engine will not turn over Gas tank empty, engine will
turn over but not start
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FMEA ExerciseBased on the example complete the
Importance Ratings of the various failuresRatings are assigned to the frequencies and effects ofthe various failures modes.
Frequencies are estimated on a scale Effects are based on severity using a scale
Overall ratings are the numerical product of each score Likelihood of failure Effect of failure Criticality of failure
The higher the score the greater the importance as asource of harm
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FMEA or FMECA
FMECA ( Failure Mode Effects and Criticality Analysis ) is similar to a FMEA, Criticality is computed in place of RPN .
FMECAs are used extensively in military, aerospace andmedical equipment fields, for both design and processreliability analysis.
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FMECA
Failure Mode Effects Criticality Analysis Systematic & proactive approach to preventing failures
before they occur Completed prior to implementation of a new system, orredesign of a system in early stage of development Systems or processes already in place.
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Criticality Analysis
In the criticality analysis method, the analysis team must: Define the reliability/unreliability for each item, at a given
operating time. Identify the portion of the items unreliability that can be
attributed to each potential failure mode. Rate the probability of loss (or severity) that will result from
each failure mode that may occur. Calculate the criticality for each potential failure mode by
obtaining the product of the three factors:
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Mil-Std-1629 Severity Levels
Category I - Catastrophic: A failure which may cause death or weapon systemloss (i.e., aircraft, tank, missile, ship, etc...)
Category II - Critical: A failure which may cause severe injury, major propertydamage, or major system damage which will result in mission loss.
Category III - Marginal: A failure which may cause minor injury, minor property
damage, or minor system damage which will result in delay or loss of availabilityor mission degradation. Category IV - Minor: A failure not serious enough to cause injury, property
damage or system damage, but which will result in unscheduled maintenance orrepair.
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Criticality Analysis
Mode Criticality = Item Unreliability x Mode Ratio ofUnreliability x Probability of Loss
Calculate the criticality for each item by obtainingthe sum of the criticalities for each failure modethat has been identified for the item.Item Criticality = SUM of Mode Criticalities
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Types of Failures
Functional failure Failure that occurs at the start of product life due tomanufacturing or material detects
DOA or
infant mortalityReliability failure
Failure after some period of use
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Reliability Prediction
Generally defined as the ability of a product to performas expected over time
Formally defined as the probability that a product,
piece of equipment, or system performs its intendedfunction for a stated period of time under specifiedoperating conditions
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Types of Reliability
Inherent reliability predicted by productdesign (robust design)
Achieved reliability observed during use
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Reliability Measurement
Failure rate ( ) number of failures per unittime
Alternative measures Mean time to failure Mean time between failures
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Reliability Function
Probability density function of failuresf(t) = e - t for t > 0
Probability of failure from (0, T)
F(t) = 1 e- T
Reliability functionR(T) = 1 F(T) = e - T
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Failure Rate Curve
Infantmortality
period
Average Failure Rate
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Average Failure Rate
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Reliability Predictions (MTBF)
Form the basis of Reliability Analyses Compute predicted system failure rate or
Mean Time Between Failures Failure Rate is usually expressed in Failures per 10 6 or
109
hours MTBF is usually expressed in terms of hours
Example: for a system with a predicted MTBF of 1000 hours, onaverage the system experiences one failure in 1000 hours ofoperation or a Failure Rate of 1000 per 10 6 hours
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Reliability Predictions (MTBF)
Methodology Use accepted standards
Model failure rates of components Analyze system
Calculate the system predicted failure rate or MTBF Evaluate prediction vs target or required MTBF
Evaluate stress or temperature reduction designchanges
Evaluate practicality of design change especiallywhen MTBF is self imposed
Q i i A h
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Quantitative ApproachThe quantitative approach uses the following formula for
Failure Mode Criticality:Cm = pt
Where C
m= Failure Mode Criticality
= Conditional probability of occurrence of next higher failureeffect
= Failure mode ratio p = Part failure rate T = Duration of applicable mission phase
Criticality Analysis Example
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Criticality Analysis ExampleA resistor R6 with a failure rate of .01 failures per million hoursis located on the Missile Interface Board of the XYZ MissileLaunch System. If the resistor fails, it fails open 70 % of thetime and is short 30 % of the time.When it fails open, the system will be unable to launch a missile30 % of the time, the missile explodes in the tube 20 % of the
time, and there is no effect 50 % of the time.When it fails short, the performance of the missile is degraded 50% of the time and the missile inadvertently launches 50 % of thetime.Mission time is 1 hour.
C iti lit A l i E l
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Criticality Analysis Example p = 0.01 in every case
= 0.7 for open
= 0.3 for unable to fire
= 0.2 for missile explodes
= 0.5 for no effect
= 0.3 for short
= 0.5 for missile performance degradation
= 0.5 for inadvertent launchCm for R6 open resulting in being unable to fire is (.3)(.7)(.01)(1)=0.0021
Cm for R6 open resulting in a missile explosion is (.2)(.7)(.01)(1)=0.0014
Cm for R6 open resulting in no effect is (.5)(.7)(.01)(1)=0.0035
Cm for R6 short resulting in performance degradation is(.5)(.3)(.01)(1)=0.0015Cm for R6 short resulting in inadvertent launch is (.5)(.3)(.01)(1)=0.0015
D i f Si Si
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Design for Six SigmaBuilt on Six Sigma Principles uses the DMADV framework. Focuses is heavy on Solution Refinement through Failure Mode
Effects Analysis (FMEA), Design Of Experiment (DOE) andSimulations.
Adds new tools like Quality Functional Deployment (QFD).
Suitable for the design of Products, Processes or services alike
DDefine
MMeasure
AAnalyze
DDesign
VVerify
Six Sigma (DFSS) is
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Customer-driven design of processes with 6 capability.
Predicting design quality upfront.
Top down requirementsflowdown (CTQ flowdown)matched by capability flowup.
Cross-functional integrated
design involvement.
Drives quality measurementand predictabilityimprovement in early design
phases.
Utilizes process capabilities tomake final design decisions.
Monitors process variances toverify 6 customerrequirements are met.
Six Sigma (DFSS) is..
DFSS Methodology
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DFSS Methodology
Define Measure Analyze Design Verify
Under-standcustomer needs andspecifyCTQs
Developdesignconceptsand high-leveldesign
Developdetaileddesign andcontrol/testplan
Testdesign andimplementfull-scaleprocesses
Initiate,scope,and plantheproject
DESIGN FOR SIX SIGMA
DELIVERABLES
TeamCharter
CTQs High-levelDesign
DetailedDesign
Pilot
TOOLS
Mgmt Leadership Customer Research FMEA/ErrorproofingProject QFD Process SimulationManagement Benchmarking Design Scorecards
DMADV - Define
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DMADV Define Understand the customers needs
Identify critical customer requirements Moment of Truth. Interaction point with customer Front-load the pain Gain consensus on goals and outcomes Build a sense of direction Create a vision of what success is Identify project scope Identify preliminary project time line End result, a design document which serves as a
guiding reference for the remainder of the project
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DMADV Analyze
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DMADV - Analyze
Identify concepts for the new product or process Identify how each step in the process contributes to
the overall performance Challenge assumptions & paradigms Absolute criteria matrix / Weighted Criteria matrix Narrow to small list of concept proposals
DMADV Design
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DMADV - Design
Details design alternatives Selects best of the best Focus on testing testing testing Once ideas are defined in sufficient details each is
evaluated in terms of failure resistance, predictedcapability and impact on Customer requirements
Ideas are simulated, tested as prototypes andoptimized to produce the best option
DMADV Design continued
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DMADV Design continued
Goal aim f or r obust solu tions Failure Mode & Effects Analysis FMEA Anti Brainstorming (Devils Advocate) Process variation analysis Process map analysis Bench Marking Simulations Design of Experiment
DMADV - Validate
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DMADV - Validate
Similar to DMAIC Control phase Testing & deployment Ensures necessary documentation, monitoring
systems and response plans are in place prior to
implementation
DFSS Principles
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DFSS Principles
1. M ust Provide value in the eye of the customer 2. Front load the pain Make it right the first time
Develop robust solutions Spend resources where itcounts the most
3. Ensure capability to meet customers needs4. Commitment to excellence5. Concentrate on communication within your team
and with your customer
Benefits of DFSS
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Benefits of DFSS Clear design strategy with clearly defined project
criteria Project focused on the Customer Vision is locked and team moves with Cohesiveness
Strong co-ordination amongst team members Issues are debugged prior to implementation Lower overall cost of implementation and operation
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C l i c k t o e d i t c o m p a n y s l o g a n .