Six Sigma 10 Improve Phase-2

8/10/2019 Six Sigma 10 Improve Phase-2

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Upendra Kachru SIX SIGMA

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






Howsever

is theeffect tothe

customer?



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






Howseveris theeffect tothe

customer?



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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Upendra Kachru SIX SIGMAUpendra Kachru

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 .

Documents

Six Sigma 10 Improve Phase-2