Sidhartha Pattnaik,
(Certified Six Sigma Green
Belt Professional)
Department of Mechanical
Engineering
College of Engineering and
Technology, Bhubaneswar
Introduction
In any industry, be it manufacturing or
service, maintaining the quality of the product is highly essential. Quality
control not only helps in ensuring cost effectiveness and higher productivity,
it also helps to acquire higher profits and customer satisfaction.
“Six Sigma” Methodology is one such
quality assurance technique. We can say Six Sigma is a methodology as well as a
philosophy that improves the quality by analyzing data with statistics to find
root cause of quality problems, improve the process and implement control. It
is a technique of measurements which results in lower defects which converts
into lower cost and competitive advantage.
Sigma (σ) is a mathematical symbol
representing one standard deviation from average or mean. Six sigma refers to
to +/- 3 σ from mean value. With six sigma there are only 3.4 defects in a
million parts, technically called 3.4 DPMO (defects per million opportunities).
A six sigma level process operates at 99.9997% quality level.
To think about in simple terms, let’s
take an example, suppose we are manufacturing soda bottles in our company and
our annual output is 1,000,000. If we are maintaining Six Sigma Quality level
in our methods of production, there will be only 3.4 (approx. 4) defective
bottles in the entire 10 lakh bottles. Isn’t it amazing?? Now let’s take the
above examples and apply is to the traditional 3 σ quality level. In three
sigma level there are 66,807 DPMO maintained at 93.3% quality level. Although
99.3% quality appears as a reasonable production output, but when we apply that
to our soda bottle plant producing 1,00,000 bottles, there are 66,807
defects!! To get hold of the seriousness
quality in production and services, think about 1 million critical drugs in 3
sigma level, 66,807 defective drugs; 1 million child care medical services,
66,807 defective service! Quality is very critical to every aspect of service
and production.
Now let’s take a close look at Six Sigma
Methodology. How it started and where is it today.
Six
Sigma and Organisation
Six Sigma effectively combines all
previous quality management techniques like TQM( Total Quality management) and
Lean Manufacturing. There are many pioneers whose contributions lead to
development of the Six Sigma philosophy. But the credit for coining the term
“Six Sigma” goes to Motorola Engineer Bill Smith along with Mikel Harry in
1980s. Six Sigma, till today is a registered trademark of Motorola.
Six Sigma can be viewed as a philosophy,
a technique or a goal. Philosophy- Customer-focused breakthrough improvement in
process; Technique- Comprehensive set of statistical tools and methodology;
Goal- Reduce variation, minimize defects, shorten cycle time, improve yield,
enhance customer satisfaction and boost bottom line.
USL- Upper Specification Limit, any
deviation beyond this is a defect.
LSL- Lower specification limit, any
deviation beyond this is a defect.
Target- this is the theoretical ideal
value
The following table shows the yield and
number of defects in various sigma level.
SIGMA
LEVEL
|
DPMO
|
YIELD
|
One Sigma
|
690,000
|
30.9%
|
Two Sigma
|
308,000
|
62.9%
|
Three sigma
|
66,800
|
93.3%
|
Four Sigma
|
6,210
|
99.4%
|
Five Sigma
|
320
|
99.98%
|
Six Sigma
|
3.4
|
99.9997%
|
Six
Sigma DMAIC Methodology
The six sigma methodology is
conceptually based on a five phase project. Each phase has a specific purpose,
tools and techniques which help in achieving the phase objectives and at the
end, six sigma goals as a whole. The five phases of Six Sigma Methodology are Define Phase, Measure Phase, Analyze Phase,
Improve Phase and Control Phase, in short DMAIC.
Define phase’s goal is to establish the project foundations,
goals to achieve, current state of challenges etc. Which are articulated in a
quantifiable manner. Valuation, Project Planning, Time Line etc are also part
of this phase. The various tools used in this phase are Project Charter, Time
line, Pareto Charts, SIPOC chart, Process Maps, CPM/PERT charts, Process
capability indices etc.
Measure phase includes obtaining measurable baseline
information about process, products etc. This also includes defining and
identifying specific processes under investigation. The tools used in this phase are Failure Mode
and Effects Analysis(FMEA), Control Charts, Basic Statistics and Probability,
Probability Distribution, Nominal Distribution, Graphical Analysis, Data
Collection plan, ANOVA etc.
Analyse phase involved detailed statistical analysis of the
project. Hypothesis Testing, regression analysis and other statistical tools
are extensively used.
Improve phase is aimed only on making the improvement like
improving the designing, testing and implementation of the solution from
previous phases. Design of Experiment (DOE), Implementation Plan, Change Plan
etc tools are used in this project.
Control phase establishes automated and managed mechanisms to
maintain and sustain improvements in the process. Poka-Yoke, Statistical
Process control etc are important tools here.
Six
Sigma Professionals
Six Sigma methods are today widely used
all around the globe across all industries. Hence highly skilled six sigma
professionals are required.
According to skills, experience and responsibilities Six sigma professionals
are organised into Six Sigma white belt, Six Sigma Yellow Belt, Six Sigma Green
Belt, Six Sigma Black Belt, Six Sigma Master black Belt and Six Sigma Champion.
Six
Sigma White Belt (CSSWB), has basic
entry level knowledge of Six Sigma from awareness perspective. He/She can
participate in local problem solving teams that supports overall projects but
not a part of Six Sigma Teams.
Six
Sigma Yellow Belt (CSSYB), is an
entry level Six Sigma professional who has general level knowledge of Six Sigma
and its methods. Participates as a Six Sigma project team member and reviews
project improvement techniques etc.
Six
Sigma Green Belt (CSSGB), have in
depth knowledge of Six Sigma Methods, processes etc; Leads six sigma Projects
and Teams; Trains Yellow belt and White belt. Project management, Team
Management and Task Management are all Green belt’s responsibility. A green
belt also supports a Black Belt in collecting and analysing quality problems.
Six
Sigma Black Belt (CSSBB) , leads Six
Sigma project, trains and coaches project team. She/he understands six sigma
methods and tools in details including supporting systems and tools. A black
belt understands all aspects of DMAIC in exact details and has six sigma
experiences over 3 years.
Six Sigma Master Black Belt (MBB),
trains and coaches black belts and green belts. A MBB functions more a Six
sigma Program Level by developing key metrics and strategic directions. A MBB
acts as an organisation’s six sigma technologist and internal consultant. A MBB
has Six Sigma Experience over 10 years.
Six
Sigma Champion is the highest level
of six sigma professional organisation. A Six sigma champion translates
company’s goals and vision to create an organisational deployment plan,
identifies project, allocates resources and removes road blocks.
Six Sigma training and Certifications
can be obtained from American society of Quality(ASQ), Aveta Business institute
and many more organisations internationally. In India, Indian Statistical
institute(ISI), KPMG, Benchmark Six sigma, Govt. Of India’s ICSL Vskills etc.
provide six sigma certification and training. Various companies have their
internal Six Sigma certification program tailored to their needs.
Other
Quality Assurance techniques
Six Sigma is the highest level of
quality assurance which incorporates previous techniques. But there are many
quality techniques which are used along with six sigma. Kaizen, TQM, Just in
Time Technique(JIT), Lean manufacturing etc.
Kaizen refers to any continuous
improvement( large or small) in an organisation. JIT caters to need of
customers when it occurs.
Lean manufacturing focuses on lean
philosophy which is about waste elimination in all forms at workplace. 5S
workplace organisation, Kanban, Muri and Muda are all Lean Techniques.
Conclusion
In today’s highly competitive economy,
quality assurance is of utmost importance. Be is customer satisfaction,
increasing profits, eliminating waste etc , Six Sigma plays a vital role in all
these aspects. Companies today work to achieve six sigma level of quality
competence at all levels.
Author
Sidhartha
Pattnaik , is a final year B.Tech
student of Mechanical Engineering at College
Of Engineering and Technology, (Biju Patnaik University of Technogy),
Bhubaneswar. He is also a Certified Six Sigma Green Belt (CSSGB) Professional
with ICSL Vskills Licence No. 7278. He can be reached at sidharthapattnaik28@gmail.com
