Six Sigma is a data-driven approach to process improvement originally developed by Motorola to reduce defects. It aims to reduce variation and errors through the DMAIC structure of Define, Measure, Analyze, Improve, and Control. The goal of Six Sigma is to achieve no more than 3.4 defects per million opportunities. This is achieved through projects led by Black Belts and Green Belts to identify and address critical quality characteristics. Successful implementation requires commitment from top management and a continuous improvement process of selecting and completing projects over time.

1. SIX SIGMA
A presentation by
THE SOCIETY
OF
STATISTICAL QUALITY CONTROL ENGINEERS
BHOPAL

2. SIX SIGMA
An overview

3. What is Six Sigma?
Six Sigma is a business initiative pioneered
by Motorola (USA) in the 1980s with the
prime objective of improving the bottom
line.
In six sigma initiative, the focus is on
reducing the defect rate at part/ process
level which, in turn, reduces cost of poor
quality, hence increase in profits.

4. About six sigma initiative
 Six sigma is a continuous improvement initiative.
 Six sigma is a process improvement initiative.
 Six sigma initiative is applicable to both business
processes as well as manufacturing processes.
 Six sigma initiative aims at reducing variation,
thereby, reducing defect rate.

5. About six sigma initiative
(Contd.)
 Six sigma initiative improves process yield,
hence, increases profitability.
 Six sigma initiative is implemented by project- by-
project approach. Six sigma projects are executed
by trained personnel (black/green belts) with
structured approach (DMAIC).
 Six sigma initiative requires patience as six sigma
projects are breakthrough projects requiring 3- 6
months to complete.

6. How six sigma objectives
are achieved
REDUCTION IN VARIATION
REDUCTION IN DEFECT RATE (DPMO)
REDUCTION IN COST OF POOR QUALITY (COPQ)
INCREASE IN PROFITS (BOTTOM LINE)

7. • Why the name SIX SIGMA?
Six Sigma initiative is all about reducing variation in
the process. An important measure of variation in the
process is “Standard Deviation”, denoted by Greek
letter (σ). In six sigma initiative, the ultimate aim is to
narrow down the variation to such an extent that six
sigma equals half of the tolerance. Hence the name.

8. Can we tolerate 1% defective!
• 20,000 lost articles of mail per hour
• Unsafe drinking water almost 15 minutes per day
• 5,000 incorrect surgical operations per week
• 2 short or long landings at most airports each day
• 200,000 wrong drug prescriptions each year
• No electricity for almost 7 hours per month

9. SIX SIGMA TARGETS
OBJECTIVE TARGET
Reduce variation 6 Sigma = ½ Tolerance
Reduce defect rate 3.4 defects per million
opportunities
(with1.5 Sigma shift)

10. HOW TO EXPRESS “DEFECT RATE”
CONVENTIONAL APPROACH:
 Number of defectives in a lot
 Number of defects per piece
SIX SIGMA APPROACH:
 Number of defect per opportunity (DPO)
 Number of defects per million opportunities (DPMO)
(DPMO is convertible to sigma quality level)
FAILURE TO CONFORM TO SPECIFIED REQUIREMENT /
PERFORMANCE STANDARD IS A DEFECT

11. SIX SIGMA Vs THREE SIGMA
The conventional processes work on three sigma limits which
corresponds to a defect rate of 0.27% or 2700 ppm. This actually means
about 3 defectives per 1000 pieces produced or 3 mistakes per 1000
processes performed. This may be OK for “average” organisatons but
not for organisations that are moving towards excellence or zero defect.
Six sigma quality level is far superior quality goal as it corresponds to a
very low defect rate of 0.002 ppm. Even with allowing a shift of 1.5
sigma to take care of practical situations, the six sigma defect rate is
only 3.4 defects in one million opportunities.
Therefore, for the organisations striving to achieve excellence/ world
class status, the goal should be to achieve six sigma quality levels in all
parts and processes.

12. SIX SIGMA Vs ZERO DEFECT
 Zero defect is theoretically not realizable. Even in
automated processes where variations are minimal,
variations do occur due to a variety of “uncontrollable”
factors.
 In statistical terms, improving quality means reducing
variation continually. This is synonymous with
increasing sigma quality level.
 Organisations that have stabilized at three sigma level,
should move towards six sigma quality level. After
achieving the goal of six sigma, next higher goal of
seven sigma, eight sigma or nine sigma may be
attempted. The road of improvement is endless.

13. SIX SIGMA
concepts

21. AN EXAMPLE
Five copper sheets were sent to laboratory for testing
(i) conductivity (ii) hardness (iii) chemical composition.
One sheet failed in conductivity test. Another sheet sheet
failed in conductivity and hardness tests. The remaining
sheets passed all tests.
Find out:
1) Proportion defective
2) Percent defectives
3) Average number of defects per unit (DPU)
4) Defect per opportunity (DPO)
5) Defects per million opportunities (DPMO)
6) Sigma level
7) Yield

22. Answers:
1) Proportion defective = 0.4
2) Percent defectives = 40%
3) Average number of defects per unit (DPU) = 0.6
4) Defects per opportunity (DPO) = 0.2
5) Defects per million opportunities (DPMO) = 200000
6) Sigma level = 2.34 (with 1.5σ shift)
7) Yield = 1 – proportion defective = 1-0.4 = 0.6 (60%)

23. IMPLEMENTING
SIX SIGMA INITIATIVE

24. SIX SIGMA INITIATIVE: STEPS
1) Set up six sigma infrastructure
2) Identify products where six sigma to be implemented
3) Identify services where six sigma to be implemented
4) Identify CTQs (critical-to-quality characteristics) for the
above products/services.
5) Identify six sigma projects linked to the above CTQs
6) Set-up six sigma project teams and time frame for
these projects.
7) Ensure successful completion of these projects.
8) Repeat the process for new set of six sigma projects.

25. SIX SIGMA INFRASTRUCTURE
SIX SIGMA CHAMPION
BLACK BELTS
GREEN BELTS

26. SIX SIGMA INFRASTRUCTURE
Six Sigma Champion
 Steers six sigma movement in the organization
 Selects six sigma projects
 Selects candidates for Black Belt/
Green belt training.
 Ensures timely completion of projects
 Removes road blocks
Six sigma champion is a senior level person enjoying management
support. He/she needs1-2 week training on the above aspects

27. SIX SIGMA INFRASTRUCTURE
Black belts
 They work full - time on six sigma projects.
 They should have analytical ability as well
as soft skills
 They require 4-5 weeks training on SQC
tools and soft skills
 They complete about 4-6 projects per year
 They could be trainers for others on six sigma
 Generally they get some certificate also
 They should not over number
(Number of black belts should not be more then 2% of
employees)

28. SIX SIGMA INFRASTRUCTURE
Green belts
 They work part time on six
sigma projects
 They get 1-2 weeks training.
 They assist black belts.
 Some times, they can do
independent projects also

29. ABOUT SIX SIGMA PROJECTS
 Six sigma projects should be breakthrough projects
 Every six Sigma project should result in sizeable
monetary benefit to the organisation
 Six Sigma projects could be based on external factors
as well as internal factors
(balance to be maintained)
 Six sigma project should have
linkage with CTQ (critical-to-quality) characteristics/
parameters

30. SIX SIGMA PROJECT CHARTER
 Project title
 Project team
 Identification of CTQ
 Time frame

31. SIX SIGMA PROJECT APPROACH
(D – M – A – I – C)
DEFINE
MEASURE
ANALYSE
IMPROVE
CONTROL

32. Achieving six sigma quality level in a
product or service is step-by-step
journey
Improvement in parts (components)
Improvement in processes
Improvement in product/service

33. Six Sigma initiative - Success Tips
 Being a major business initiative, Six Sigma should be
driven by the top management.
 Guard against the following pitfalls:
i) Six Sigma projects selected in haste without linkage to
CTQ and without assessment of expected monetary
returns.
ii) Preoccupation of black belts with routine jobs
iii) New set of projects not ready by the time one
set of projects are complete.
iv) Recommendations of Six Sigma projects are
not institutionalized, improvements not sustained.
 The process of project selection and execution
should go on continually till the six sigma quality
level is achieved in all the parts and processes.