Six Sigma Six Sigma
- Understanding basic concepts- Understanding basic concepts
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Business Relevance of 6σ
Improvement(in Qly, Cost, Del & Serv.)
Maintenance(Old Products & Services)
Customer
Govt. Policies
Substitution
Competition
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Gap analysis – Do’s & Needs
SupplierCustomer
Defect Free
Cost
Cycle Time
Quality
Price
DeliveryDo’s
Gaps to be addressed continuously
Needs
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Six sigma – Simple concept
6 σ is a level of performance that reduces the
defects in products & services significantly
A set of statistical tools that helps to measure,
analyse, improve and control processes.
A commitment to customers to achieve an
acceptable level of performance
Mind Set + Tool Set = Six σ
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6 Sigma Theme
Customer focussed
Processes are key drivers
Fact driven and Proactive for creativity
Result oriented - demands financial
analysis to verify gains
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6 Sigma Theme
Voice of Customer (VOC): Specs decided by
customers (Dependent variable, say Y)
- Response time; TAT; Breakdowns; Product
performance, waiting time at ATM/counter
etc.
Voice of Process (VOP): Variability of a
process; Process variations cause defects
(Independent variable, say x)
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6 Sigma Quality Theme
Six Sigma QualityHitting the
Target(Centralise the
Process)
Elimination of Process
variability
Process should be with minimum variability and on the target
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What does 6 Sigma do?
Real life problem Statistical solutionStatistical problem
Real life solution
Y y y = f(xi)
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6 Sigma Steps - RDMAIC
Step 6Control
Step 5Improve
Step 4Analyse
Step 3Measure
Step 2Define
Step 1 Recognition
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6 Sigma Steps - RDMAICStep 1
Recognition1. To identify the major
business issues
2. To recognise key processes that need improvement
3. Areas that need break throughs
1. Identify critical to customer (CTC)
2. Drill down to CTQ (translating expectations to parameters);
3. Define specs, UL & LL, Targets
Y= f (xi)
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6 Sigma Steps - RDMAICStep 1
RecognitionTools generally used
1. QFD Matrix
2. Importance gain matrix
Project selection criteria
• high gain
• low hanging fruits
• Urgency
• Efforts required
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1. Define the key requirements to customer
2. Customers know their language
3. Listening to customers means understanding their needs.
4. Drill down the CTC
Step 2Define
Step 1 Recognition
6 Sigma Steps - RDMAIC
Customer say… Engineers say..
• Long life 20,000 Hrs life• Reliable 3000 MTBF• Comfort cooling 24 ± 1 Deg C
Define step will deliver
• Project Chartering
(Goal, Milestone, Roles)
• Process Mapping (SIPOC model)
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1. Input, Process and output measures are to be defined
2. Measure process stability
3. Measure repeatability and reproducability
4. Measure current process capability
Step 3Measure
Step 2Define
Step 1 Recognition
6 Sigma Steps - RDMAIC
Standard softwares are availableto process the data
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Total surface area 100%
1 111 1 1
68.26%
95.44%
Lower ControlLimit
99.78%
Upper Control Limit
X
3 Sigma process
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Customer perceive and register
the variance more than average
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66
Lower Spec.
X
Upper Spec.
6 Sigma process (statistical vision)
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DefectsDefects
Countable failures that are associated with a single unit.A single unit can be defective but may contain more than one defect.
DefectivesDefectives
Completed units that are classified as bad or not meeting specs. Whole unit is said to be of defective.
Defects vs Defectives
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DPUDPU
DPU= Defects / unit
DPMODPMO
DPMO = DPMO =
DPU x 1,000,000DPU x 1,000,000
Opportunities per unitOpportunities per unit
DefectsDefects
OpportunitiesOpportunities= x 1,000,000
= Defects per million opportunities
Terminologies used
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Sigma Defects per Million (DPMO)
2 308,537
3 66,807
4 6,210
5 233
6 3.4
% non-defective
69.1%
93.32%
99.379%
99.9767%
99.99966%
24%
6%
0.6%
0.023%
6 Sigma process (measures)
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Example 1 :
52 defects, 250 AMC proposals, 4 defects opportunities / proposal
DPMO = [(52)/ (250*4)] X 1000000
= 52,000 = 3.1 Sigma level
Example 2 :
99 defects, 750 products, 150 defects opportunities /productDPMO = [(99)/ (750*150) ]X 1000000
= 880 = 4.65 Sigma level
Traditional approach
5 applications were rejected (contains 52 defects)
5/250 = 2% rejection
Traditional approach
10 products were rejected (contains 99 defects)
10/750 = 1.33% rejection
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Observation
Indi
vidu
al V
alue
28252219161310741
20
15
10
5
0
_X=9.97
LCL=0.70
UCL=19.23
Observation
Mov
ing
Rang
e
28252219161310741
10.0
7.5
5.0
2.5
0.0
__MR=3.48
UCL=11.38
LCL=0
Stability Analysis Chart of Time taken for replacement
Software (Minitab) outputs – some screens…..
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Software (Minitab) outputs – some screens…..
Time taken for replacement (day
Perc
ent
20151050
99
9590
80706050403020
105
1
Mean
0.245
9.967StDev 3.819N 30AD 0.459P-Value
Probability Plot of Time taken for replacementNormal
P > 0.05
Data follows normal distribution
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Software (Minitab) outputs – some screens…..
1612840
LSLUSLProcess Data
Sample N 30StDev(Within) 2.89562StDev(Overall) 3.8521
LSL 0Target *USL 1Sample Mean 9.96667
Potential (Within) Capability
CCpk 0.06Overall Capability
Pp 0.04PPL 0.86PPU -0.78Ppk
Cp
-0.78Cpm *
0.06CPL 1.15CPU -1.03Cpk -1.03
Observed PerformancePPM < LSL 0.00PPM > USL 1000000.00PPM Total 1000000.00
Exp. Within PerformancePPM < LSL 288.74PPM > USL 999021.32PPM Total 999310.06
Exp. Overall PerformancePPM < LSL 4836.07PPM > USL 990036.94PPM Total 994873.02
WithinOverall
Process Capability of Time taken for replacement
Long term
Short term
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Step 4Analyse
Step 3Measure
Step 2Define
Step 1 Recognition
6 Sigma Steps - RDMAIC
1. Identify cause & effect [ y = f (x) ]
2. Use analytical tools to vital few
3. Short list causes that are vital few which can be taken to improve phase
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6 Sigma Steps - RDMAIC
Identify and formulate causes
Quantify and verify causes
Identify Opportunities
• process mapping• FMEA• QFD•Process Capability•Stratification• Seven QC tools• Why-why analysis• Brainstorming
• Identify success factor
• List of opportunities in vital few
• Hypothesis tests• DOE
Y = f(x1, x2, x3, x4, x5,……..xn)
This s the function that models and quantifies the relationship between X & Y
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Step 5Improve
1. To find out vital causes (x)
2. Optimal value of causes
3. Verify optimal setting with set tolerances
Step 4Analyse
Step 3Measure
Step 2Define
Step 1 Recognition
6 Sigma Steps - RDMAIC
DOE is one of the tools used to establish relationship between inputs & outputs
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1. Measurement System validation for inputs
2. Process capability
3. Implementation of SPC Charts
Step 6Control
Step 5Improve
Step 4Analyse
Step 3Measure
Step 2Define
Step 1 Recognition
6 Sigma Steps - RDMAIC
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FMEA
FMEA is an analytical technique used by designers, engineers and analysts to ensure that all design or manufacturing or process failure modes have been considered and are assessed with a view of elimination.
• System FMEA • Process FMEA• Product/Design FMEA
What is a failure?
A component or system not meeting or not functioning as per design (Ex. Break failure)
What is a failure mode?
The manner in which a component or a system failure occurs (Ex. leakage of break oil )
What is an Effect?
The impact or consequence of failure (vehicle meeting accident)
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FMEA
1. Severity of effect? (Scale 1-10)
2. Possibility of failure? (scale 1-10)
3. Possibility of detecting? (scale 1-10)
Severity of impact
Prob. of occurrence Detectability
1. 8 2 4
Degree of chances that it gets detected before it goes to customer
RPN(Risk Priority Number)
64(Max 1000, Min 1)
2. 4 6 9 216
Work on high RPNReduce severity, rarely changesReduce prob of occurrence (Have parallel system, hand break)Improve detectability (process, tests, reliability)
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QFD
Tool used priorities the areas to focus. C
usto
mer
Req
uire
men
ts
Y
y1y2
y3y4
y5
Importance X1 X2 X3 X4 X5
52
4
3
1
3
4 3
2
3
1
2
7
5
1
6
4
2
3
56
1
H
M L
3257
Proj to focus
Correlation between X’s
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DOE
Structured proactive process for finding relationship between input and output factors.
Multiple input factors are considered and controlled simultaneously to ensure that the effect on the output is significant.
Why DOE?
• To find out vital few Xs that influence the quality of Y
• To identify the best combination of values of Xs to get the optimal value of process performance
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Sigma level - Customer focus
00 Sell & forgetSell & forget
11 Know what happens to sold productsKnow what happens to sold products
22 Inspect before despatch (QC)Inspect before despatch (QC)
33 Inspect the process (Process monitoring)- QCInspect the process (Process monitoring)- QC
44 Control the processControl the process
55 Understand the process & control it (SPC)Understand the process & control it (SPC)
66 Re-engineer the process in line with customers’ Re-engineer the process in line with customers’ expectation (RDMAIC)expectation (RDMAIC)
77 Right product meeting expectations (RDMAIC)Right product meeting expectations (RDMAIC)
88 Understand customer requirements & design prod / Understand customer requirements & design prod / service features defect free (Design for 6 service features defect free (Design for 6 σσ))
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Sigma level of different sectors
1 2 4 5 6 73
Tax advice Prescriptionwriting Restaurant bill
Payroll processing
Air Lines Baggage handling
Best in Class Air Lines safety
1000,000
100,000
100
10,000
1000
10
1
Defects in PPM
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Thank you
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