Transcript
Six Sigma
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•Sigma is a letter in the Greek alphabets•The term “Sigma” is used to denote distribution or spread around the mean (average) of any process or procedure•For a business or manufacturing process, the sigma value is a metric that denotes how well the process is performing•The higher the sigma value the better. The sigma value measures the capability of the process to deliver defect free output•A defect is anything that results in customer dissatisfaction•With “Six Sigma” the common measurement index is defects per unit where a unit could be anything--a component, piece of material, time frame, distance etc.•The higher the sigma value, the less likely a process will produce defects.•As sigma value goes up, customer satisfaction naturally goes up.
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What is Sigma?
• Sigma is a statistical measure (Standard Deviation) denoting level of defects in a process/parameter
• It is a means to denote variation in a process
• Examples of Control limits and Std Dev.
Day Process 1 Process 21 49.4 43.82 47.7 51.23 49.2 47.64 49.1 46.65 49.9 57.06 48.6 53.37 47.9 59.68 53.2 46.89 48.9 55.410 48.1 40.311 51.0 60.212 50.1 46.213 54.3 54.714 49.4 51.115 52.2 57.516 45.5 54.117 56.8 53.618 55.1 49.019 48.2 55.620 50.2 45.0
Process 1
35
38
41
44
47
50
53
56
59
62
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1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49
Days
Spec
s
Process 2
35
38
41
44
47
50
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56
59
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1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49Days
Spec
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Customer requires Target value50 and range from 40 to 60.Which process has the capabilityto meet customer requirements?
Process 1 : Mean is 49.8Std Deviation is 2.53, Ranging from 56.8 to 42.8
Process 2 : mean is 49.8Std Deviation is 4.39, Ranging from 60.2 to 38.9
Time Series Chart
6065707580859095
100105110115120125130135
1 5 9
13 17 21 25 29 33 37 41 45 49 53 57 61 65 69 73 77 81 85 89 93 97
No of Days
Spec
s
From To Counts71 75 176 80 281 85 386 90 1091 95 1296 100 22
101 105 20106 110 17111 115 8116 120 3121 125 2
Y
Freq
uenc
y
1301201101009080
25
20
15
10
5
0
Mean 99.67StDev 10.02N 100
Histogram of YNormal
0.13%
34.13% 34.13%
13.06% 13.06%2.14%2.14% 0.13%
Mean-3σ +1σ-1σ +2σ-2σ +3σ
68.26%
95.46%
99.73%
Measurement:Measurement: Variance is the Enemy Variance is the Enemy
In the chart below, 64.6% of the measures are between the In the chart below, 64.6% of the measures are between the upper and lower limitsupper and lower limits
This is a 1This is a 1 process process Reducing the variations in the process will bring a higher Reducing the variations in the process will bring a higher
percentage within the acceptable limitspercentage within the acceptable limits
Mean (μ) +1σ-1σ-2σ +2σ-3σ +3σ
34.13 %34.13 %
13.06 % 2.14 %
13.06 % 2.14 %
0.13 % 0.13 %
LowerLimit
UpperLimit
Measurement:Measurement: Variance is the Enemy Variance is the Enemy
Time IntervalsTime Intervals Time IntervalsTime Intervals
Mean
Mean
W I D E VariationW I D E Variation Slim VariationSlim Variation
Time (Min.).Time (Min.).
Target
Target
CustomerUpper Limit
CustomerUpper Limit
DEFECTS
ZERODEFECTS
Time (Min.).Time (Min.).
Control Chart
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
UCL
LCL
Sample number
Mean
Out ofcontrol
Normal variationdue to chance
Abnormal variationdue to assignable sources
Abnormal variationdue to assignable sources
Tracking ImprovementsUCL
LCL
LCLLCL
UCLUCL
Process not centeredand not stable
Process centeredand stable
Additional improvementsmade to the process
Different Shapes of Distributions
Establishing the Focus
Quality
It is the performance to the standard as expected by a customer
Customer
Anyone internal or external to the organisation who comes in contact with my work, product or service
Anyone whose satisfaction depends on my output and actions
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Process CapabilityProcess Capability StandardsStandards Defects per Defects per mm oppnmm oppn..Sigma levelSigma level
3 3 HistoricalHistorical 66,80766,807
Current bestCurrent best 6,210 6,210
New with 6New with 6
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What is Six Sigma?Not only a statistical tool but, • An attitude which continuously and relentlessly
strives to achieve an almost zero defect level in any process.
• It is this attitude which gives maximum results in the longer run.
• It also makes the organisation robust
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Why Six Sigma?• A structured tool/methodology to reduce and
thereafter control defects in any process• Reducing defects translates to
– Better understanding of customer requirements– Better customer satisfaction– Increased customer loyalty– Increased revenues– Reduction in costs
Y=f ( X, X1………Xn)
Y•Dependent•Output•Effect•Symptom•Monitor
X•Independent•Input/Process•Cause•Problem•Control
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Capability=f(Variation)
The Chain of Causation•Our survival is dependent on growing the businessOur survival is dependent on growing the business•Our business growth will depend on customer Our business growth will depend on customer satisfactionsatisfaction•Customer satisfaction is governed by quality, price Customer satisfaction is governed by quality, price and deliveryand delivery•Quality, price and delivery are controlled by Quality, price and delivery are controlled by process capabilityprocess capability•Process capability is greatly limited by variationProcess capability is greatly limited by variation•Process variation leads to increase in defects, cost Process variation leads to increase in defects, cost and cycle timeand cycle time•To eliminate variation we must apply the right To eliminate variation we must apply the right knowledgeknowledge•In order to apply the right knowledge, we must In order to apply the right knowledge, we must first acquire itfirst acquire it..
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Defect Reduction
Yield Improvement
Customer Satisfaction
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The Role of Measurement•If we cannot express what we know in the form of numbers then we do not know much about it•If we do not know much about it then we cannot control it•If we cannot control it then we are at the mercy of chance
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BreakthrouBreakthrough Strategygh Strategy
OptimisationOptimisation
CharacterisatCharacterisationion
( Identificatio( Identification of Project ) n of Project )
ControlControl
ImproveImprove
AnalyseAnalyse
MeasureMeasure
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1 1 Select CTQ Characteristic 2 Define Performance Standards3 Validate Measurement System4 Establish Product Capability5 Define Performance Objectives6 Identify Variation Sources7 Screen Potential Causes8 Discover Variable Relationships9 Establish Operating Tolerances10 Validate Measurement System11 Determine Process Capability12 Establish Controls
Measure NCapabilityOK? Analyse Improve ControlY
Y
Y
N
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ModifyDesign?
CapabilityOK?
Redesign
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How is “Six Sigma” implemented in an organisation?
• Total commitment and trust from the management is a key to success
• Champions for critical business areas• Dedicated “Black Belts” for each project• Process Owners to define a project and it’s
charter
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How is “Six Sigma” implemented in an organisation? (Continued)
Business Area examples,• Manufacturing
– Production, Maintenance, Electrical systems etc.• Research & Development, Market/Sell• Finance, HR, Working Capital Mgmt
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How is “Six Sigma” implemented in an organisation? (Continued)
Champions are essentially the leaders from business areas who possess thorough knowledge of the processes. They are responsible for,
• Defining and then prioritising the projects and preparing Project Charters
• Tracking Project progress• Reporting to the top management on the status and progress of the
projects
They also act as counselors to the Black Belts
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How is “Six Sigma” implemented in an organisation? (Continued)
Black Belts• Black Belts are essentially drawn from various business areas
and are then fully dedicated to the “Six Sigma” projects• They undergo training in the Six Sigma methodology• They are responsible for executing the project and also for the
project success based on predefined criteria, charter.• They lead a team (Green Belts) of employees from the business
areas which assists them in executing the projects
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How is “Six Sigma” implemented in an organisation? (Continued)
Qualities of a Black BeltBlack Belts are vital to the success of Six Sigma• They should possess a good knowledge of the business• They should possess leadership qualities• They should be self motivated and go getters
In effect they should be those employees whose absence will be felt in their departments
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How is “Six Sigma” implemented in an organisation? (Continued)
Financial Green belt• All the projects need to add to the bottom line of the
company• The financial impact and real savings are tracked and
monitored by Financial Green belts.• They are independent of the project team and act as
“unbiased third party” to audit the improvements
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Six Sigma : Project stages(MAIC)• Measure• Analyse• Improve• Control
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Six Sigma : Project stagesMeasure• Data collection and evaluation of current
Process Capabilities (sigma levels)• Preparation of Process Flow• Input and Output variables• Failure Modes and Effects Analysis (FMEA)
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Six Sigma : Project stagesAnalyse• Statistical analysis and correlation of
parameters• Root Cause Analysis• Analysis of Behaviour (ABC and BOC)• Identify parameters for improvement
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Six Sigma : Project stagesImprove• Design of Experiments (DOE) based on
Analyse phase• Analyse data from experiments• Draw conclusions
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Six Sigma : Project stagesControl• Prepare plan to Manage Change• Prepare modified Process Flow• Prepare a control plan document• Pin point responsibilities for the change• Identify process owners for control purposes
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• Any Questions???
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