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What is Six Sigma?What is Six Sigma?
Six Sigma is a business strategy that usesstatistical and non-statistical tools andtechniques, change management tools,
project management skills, teamwork skillsand a powerful roadmap to maximize anorganization's return on investment (ROI)through the elimination of defects inprocesses.
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What makes Six Sigma differentWhat makes Six Sigma different
from other quality managementfrom other quality managementinitiatives?initiatives?y Clear focus on achieving measurable and quantifiable financial
returns
y Importance on strong and passionate leadership
y Integrates human elements (culture change, customer focus,
belt system infrastructure, etc.) and process elements(process management, statistical analysis of process data,
measurement system analysis, etc.) of improvement
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y Utilizes the tools and techniques for fixing problems in business
processes in a sequential and disciplined fashion
y Creates an infrastructure of Champions, Master Black Belts
(MBBs), Black Belts (BBs) and Green Belts that lead, deploy and
implement the approach
y Utilizes the concept of statistical thinking and encourages the
application of well-proven statistical tools and techniques for
defect reduction through process variability reduction methods
What makes Six Sigma differentWhat makes Six Sigma different
from other quality managementfrom other quality managementinitiatives?initiatives?
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Benefits of Six SigmaBenefits of Six Sigma
y Effective management decisions due to heavy reliance
on data and facts instead of gut-feelings and
y Increased understanding of customer needs and
expectations
y Increased cash flow by making processes more
efficient and reliable
y Improved knowledge across the organization on
various tools and techniques for problem-solving
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y Reduced number of non-value-added operations
through systematic elimination, leading to faster
delivery of service, faster lead time to production,
faster cycle time
y Reduced variability in process performance, product
capability and reliability, service delivery and
performance
y Transformation of organizational culture from being
reactive to proactive thinking or mindset
Benefits of Six SigmaBenefits of Six Sigma
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Six Sigma MethodologySix Sigma Methodology
Five-stage methodology:
y Define phase - involves identifying a project's CTQ (critical-to-
quality) characteristics driven by the voice of the customer
y Measurement phase - identify the key internal processes that
influence CTQ characteristics and measures the defects currently
generated
y Analysis phase - establish process capability and define
performance objectives by benchmarking and identifying the
sources of variation
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Five-stage methodology:
y Improvement phase - confirm the key
variables or causes and quantifies their
effects on the CTQs
y Control phase - develop corrective actions,
new standards and procedures, finalizedocumentation and share the key lessons
learned from the project
Six Sigma MethodologySix Sigma Methodology
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ASPIRE and Six Sigma at TataASPIRE and Six Sigma at Tata
SteelSteely Until 2002, Tata Steel was following a modular framework
that used numerous tools and techniques to bring about
process improvements
y Numerous process/performance improvement techniques
and models, such as VE, ISO, QIP, TBEM, etc., were adopted
over the years. But they did not have a perspective or
organized framework that would guarantee that the problem
solutions developed were the best or most optimal ones.Also, due to the localized and contextual nature, the leverage
of solutions developed for one problem was not available for
other similar problems
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y In order to address this issue and providean integrated framework Six Sigma
methodology was started in June 2002
y It was later merged with other initiativeslike total productive maintenance (TPM),
5S, value engineering (VE), Poka-Yoka,theory of constraints and named asASPIRE (Aspirational Initiatives to RetainExcellence).
ASPIRE and Six Sigma at TataASPIRE and Six Sigma at Tata
SteelSteel
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ASPIRE DMAIC methodology (DMAIC, DefineASPIRE DMAIC methodology (DMAIC, Define--MeasureMeasure--AnalyzeAnalyze--ImplementImplement--Control) was deployed atControl) was deployed atTata SteelTata Steel
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Need for ASPIRE DMAIC approachNeed for ASPIRE DMAIC approach
y For the production of 1 ton of hot metal
400500 kg of coke is required
y Coke is produced by carbonization of
coal at about 10001100C
y The coke so produced then undergoes a
quenching process.
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y A need was felt to bring about improvementin the average levels of residual cokemoisture achieved as well as keeping its
standard deviation low
y A large number of improvement projectstaken in the past but these projects had not
been able to make a permanent impact onthe intended objectives. Therefore, thisprocess was chosen for ASPIRE DMAICapproach for improvement
Need for ASPIRE DMAIC approachNeed for ASPIRE DMAIC approach
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ASPIRE DMAIC approach forASPIRE DMAIC approach for
improvementimprovement in the average levelsin the average levelsof residual coke moistureof residual coke moisturey Define phase - the CTQ identified was
moisture % in coke and moisture content in
coke should never be more than 3.5%y Measure phase
a) Measurement of coke moisture was carriedout every shift by recording the loss in weight
of the sample during testingb) A Gage R&R study was used to validate themeasurement system
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Average coke moisture from yearAverage coke moisture from year
1999 February to 2002 February1999 February to 2002 February
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y Analyze phase -a) The upper specification limit of cokemoisture was defined as 3.5%
b) A target was taken to improve thesigma level of moisture up to3 (corresponding to 6.7% defect)
c) To improve the coke moisture someproblem areas were identified afterbrainstorming and these were analyzedwith the help of a failure modes andeffects analysis' (FMEA)
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FMEA performed onFMEA performed on
quenchingquenchingProcess/operation/function
Failure
mode
Effect of
failureSeverity Causes Occurrence Control Detectability
Quenching Inconsisten
cy in flow
rate
Different
amount of
water used
4 Different water
level in quenching
tank
7 No control 8
Leakage of
water
Extra water
added
6 Leakage from dry
fog nozzles, flap
sealing, sprayingvalve
5 Time-to-time
maintenance
5
Double
quenching/s
potquenching
Excess
moisture in
coke
8 Initial quenching
not proper, faulty
parameter design
9 By experience 6
Non-
uniformdistributionof coke on
quenching
car
Hot coke in the
wharf
7 No
synchronizationof speed betweenloco and pusher
ram
8 Controlled by
skill level ofoperator
7
Water
carry over
in thewharf by
quenching
car
Higher
moisture
7 Improper drain-
out, improper
parameter design
5 By experience 6
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d) Factors that impact the moisture level incoke were identified. After a detailed analysis,
three critical parameters were shortlisted: Quenching time
Crack opening time
Drain-out time
y Improve phase
Once the parameters were finalized theoptimal combinations of these parametersfor getting lower average value and standarddeviation of the coke moisture weredetermined.
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Control phase
a) After implementing the best possiblecombination the challenge was to make theperformance of coke moisture consistent
b) the average value of coke moistureimproved from a base value of 3.432.7%.Standard deviation of coke moisture alsoimproved from 0.9 to 0.44
c) To sustain the improvement in the longrun a rigorous automated controlmechanism was followed
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THANK YOU
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