Importance of Six Sigma

Introduction

The Greek alphabet Sigma (styled as σ) is used in Statistics as a symbol of Standard Deviation (SD), which stands for a quantification of deviation or variation from a set of standard Data range.

The Six Sigma or 6σ is a term which owes its root to terminologies related to statistical sculpts of industrial processes. The Six Sigma is an overall rating which indicates an almost defect-free status of an industrial manufacturing process. In a Six Sigma process the output of a manufacturing facility should ideally have 99.99966 % perfection or 3.4 Defects Per Million Opportunities (DPMO).

Evolution of Quality Concept:
   

In early part of the twentieth century the industrial entrepreneurs were facing a serious problem regarding rejection of finished goods, which was a serious loss in terms of money, man-hour and frequent failure to meet delivery deadlines. In 1930 Walter A. Shewhart, an American physicist and Statistician first pioneered the concept of Statistical Process Control (SPC). His was the concept that revolutionized the manufacturing capabilities of American industries manifold during WWII.  After the Second World War, ISO came into existence in 1947. And ISO 9000 was launched in 1987 which was based on British Standards i.e. BS 5750 series. Meanwhile, in US two engineers of Motorola Inc., namely Mr. Bill Smith and Mr. Mikel J. Harry gave birth to the concept of Six Sigma methods in 1986.

A few words about Six Sigma method:

Although the six sigma method was invented by Motorola engineers, Bill Smith and Mikel J. Harry but GE, Honeywell, Dow Chemicals used this philosophy more than others to reduce their wastes and subsequently increase their savings by billions of dollars.

An important announcement made by GE in 1998 helped in spreading the popularity of Six Sigma. They saved $350 million by implementing Six Sigma. A lean production process cuts off losses and later on the figure touched more than $1 billion. 

The basic objective of Six Sigma method is to increase profitability of an Organization by reducing wastes and by enhancing maximum customer satisfaction.

The Six Sigma method or techniques is targeted to achieve no more than 3.4 DPMO output. But the standards set by Six Sigma methods may vary depending on the nature of business or product of the organization. For e.g. the yardstick of 3.4 DPMO from the raw material suppliers of circuit boards to a Smartphone manufacturer will not fetch desired quality benchmark of 3.4 DPMO, because the circuit components should be 100% defect free. The critical components of Six Sigma are abbreviated as DMAIC i.e. Define, Measure, Analyze, Improve and Control.

To accomplish Six Sigma quality, a system must not produce more than 3.4 DPMO (Defects per Million Opportunities). An 'opportunity' is termed as a probability or possibility of deviation from stipulated specifications or simply called Non-conformity. Therefore, Six Sigma quality needs to be almost unblemished in expediting the major course of action in an industrial process.

Hence, Six Sigma takes into account six major factors, those are, Critical about Quality, Defect in finished product, Process capacity, Variation to enhance customer satisfaction, Stable operations , Design for Six Sigma.

Mathematically speaking, a Six Sigma Process is defined as the output being a process Function of the inputs. If, X is the key process input variable or raw material in a process, then key output variable or finished product shall be   Y = F(X)

Some basic Key Words of Six Sigma:

KPIV – Key Process Input Variable

KPOV-Key Performance Output variable

DPMO-Defects Per Million Opportunities

CSSGB-Certified Six Sigma Green Belts

DFSS-Design For Six Sigma

DMADV- Define, Measure, Analyze, Design and Verify

IDOV – Identify, Design, Optimize and Verify

QFD – Quarterly Functional Deployment

FEMA – Failure Modes and Effects Analysis

VOC- Voice of Customer

Six Sigma Tools:

The Design tool DFSS is different from DMAIC because DFSS is applied for any new process, whereas, DMAIC is applied only for the existing process of manufacturing.  DFSS has two major variants namely, DMADV and IDOV. Apart from these QFD and FEMA are also used.

The DMADV is used for a new process and has five phases like:-

Define – This is the first phase, where the target is designed to achieve customer satisfaction,

Measure – In this 2^nd phase the process is measured to identify critical characteristics,

Analyze – In this phase the design is analyzed so as to develop and design alternatives,

Design – An improved alternative is designed.  

Verify – Finally the improved design is verified and validated if found compatible.

IDOV is used to cater to a completely new requirement of customer and consists of four

phases:-

Identify- Here the specific customer needs are identified

Design- In this phase, permutation and combination is done with process parameters and inputs so as to determine the proper process required to meet the customer’s specific needs.

Optimize- The basic resources are utilized optimally to achieve maximum customer satisfaction

Verify- In this phase the design is tested and only after 100% competency it is approved.

QFD is needed to know customer needs by utilizing VOC and design the process in line with that and manufacture the product accordingly.

The other DFSS tool used to analyze risk management is FMEA-Failure Modes and Effects Analysis

Six Sigma Calculations:                                                                                                                   

The six sigma calculation is based on the following formulae:-

 DPMO = {(Total Defects) ÷ (Total Opportunities)} × 1000000

% of Defects = {(Total Defects) ÷ (Total Opportunities)} × 100
% of Yield = 100 – (Defects in Percentage)
Process Sigma = NORMSINV [1 - {(Total Defects) ÷ (Total Opportunities)}] + 1.5

                                                       OR,

Process Sigma = 0.8406 +    SQRT [9.37 – 2.221 × {(in (DPMO)}]

 

Six Sigma Certification:

The certification offers an individual the expertise to understand and utilize the tools and methods of Six Sigma to enhance the manufacturing potential of his organization to achieve almost flawless output. There are various levels of certification which replicate the martial art classification such as Master Black belt, Black belt, Green belt, Yellow Belt and White belt. The Belt mirrors the individual’s status in the Organization.

The Belt Hierarchy: 

The Belts symbolize the skill, power, responsibilities and accountability of an individual within an organization practicing Six Sigma.

Levels or hierarchy in six sigma:

1. The topmost executives, who are the final decision makers in an Organization, own Six sigma. They provide with leadership and direction and decide on implementing Six Sigma.

2. Six Sigma Champions- they Coach MBB or Master Black Belts. They decide on identifying the scope of the projects and develop strategies befitting the Organization.

3. Master Black Belts –they take overall responsibilities for the implementation of the projects and processes by coaching Black Belts and Green Belts and other functionaries below them.

4. Black Belts - They are attached to specific Projects and devise strategies for specific projects and are Team leaders. They are supported by Green Belts and other functionaries below them.

5. Green Belts – They take care of routine jobs and assist Black Belts and take responsibilities for the effective implementation of the strategies devised by their leaders.

Conclusion:

Although, Six Sigma finds its success in any work environment, such as Healthcare, IT, Banking, Finance, Manufacturing, Radio & Telecommunications, but the basic limitation of application lies in the matter of size of the Company. Business analysts and consultants pointed out one important factor which should not be ignored, is that Six Sigma is a process which should be implemented for Companies with huge workforce, it will not be successful or cost –effective in that sense if the manpower of the organization is less than 500 or so.