Six Sigma - Understanding basic concepts

Six Sigma Six Sigma

- Understanding basic concepts- Understanding basic concepts

Saturday, April 22, 2023Saturday, April 22, 2023 22

Business Relevance of 6σ

Improvement(in Qly, Cost, Del & Serv.)

Maintenance(Old Products & Services)

Customer

Govt. Policies

Substitution

Competition


Gap analysis – Do’s & Needs

SupplierCustomer

Defect Free

Cost

Cycle Time

Quality

Price

DeliveryDo’s

Gaps to be addressed continuously

Needs


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


6 Sigma Theme

Customer focussed

Processes are key drivers

Fact driven and Proactive for creativity

Result oriented - demands financial

analysis to verify gains


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)


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


What does 6 Sigma do?

Real life problem Statistical solutionStatistical problem

Real life solution

Y y y = f(xi)


6 Sigma Steps - RDMAIC

Step 6Control

Step 5Improve

Step 4Analyse

Step 3Measure

Step 2Define

Step 1 Recognition


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)


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


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


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)


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


Standard softwares are availableto process the data


Total surface area 100%

1 111 1 1

68.26%

95.44%

Lower ControlLimit

99.78%

Upper Control Limit

X

3 Sigma process


Customer perceive and register

the variance more than average


66

Lower Spec.

X

Upper Spec.

6 Sigma process (statistical vision)


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


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


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)


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


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…..



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



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


Step 4Analyse

Step 3Measure

Step 2Define

Step 1 Recognition


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



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


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


DOE is one of the tools used to establish relationship between inputs & outputs


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



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)


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)


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


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


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))


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


Thank you

Documents

Six Sigma - Understanding basic concepts