Six Sigma is literally the range in which most errors will occur, but the term has earned a greater meaning. Many large corporations throughout the world use the Six Sigma process to improve their organization’s performance. It is not a quality standard or a management system to measure and report results, but – when properly used – it is a way of thinking about your organization and most importantly your customers, both external and internal. Lean is the toolbox for dealing with issues to improve flow in business processes and originates from the Japanese automotive industry.

Definition

Six Sigma can be defined as a methodology to reduce process variations that cause defects, defined as unacceptable deviation from the mean or target; and to systematically work towards reducing variation to eliminate those defects.

Mathematics

In the 1980s Bill Smith was able to demonstrate where Motorola’s production process could be optimized further. Instead of using the traditional quality methods of that time, he measured the number of defects per million opportunities in a certain process.

Frederick Gauss (1777-1855) developed the mathematical concepts that are used in Six Sigma. His normal distribution curve describes how probability is distributed. Or, in normal English, how likely it is that a value higher or lower than the average is encountered. The standard deviation, a measure for the spread in the normal distribution, is represented by the Greek lower case letter sigma (s).

Note that not all measurements will results in a Gaussian distribution. Read more about statistics in the Tools & Skills section of this site.
 

Improved Performance

If this Motorola approach did not have the desired effect, nobody – apart from mathematicians - would ever have heard of Six Sigma. But the commitment to use the results from this research and the determination to find ways to reduce the number of defects, led to impressive cost savings. More than $ 16 billion, claims Motorola.

This success inspired General Electric, Allied Signal, and other large corporations to implement Six Sigma throughout their organizations.

Tools & Skills

Six Sigma has two key methodologies – DMAIC (Define Measure Analyze Improve Control) and DFSS (Design for Six Sigma). DMAIC is used to improve an existing business process. Sometimes a DMAIC project may turn into a DFSS project because the process in question requires complete re-design to bring about the desired degree of improvement.

DMAIC

Basic methodology consists of the following five phases:

• Define formally define the process improvement goals that are consistent with customer demands and enterprise strategy.
• Measure to define baseline measurements on current process for future comparison. Map and measure process in question and collect required process data.
• Analyze to verify relationship and causality of factors. What is the relationship? Are there other factors that have not been considered?
• Improve optimize the process based upon the analysis using techniques like Design of Experiments and Lean.
• Control setup pilot runs to establish process capability, transition to production and thereafter continuously measure the process and institute control mechanisms to ensure that variances are corrected before they result in defects.

DFSS

Design for Six Sigma (DFSS) is a separate and emerging discipline related to Six Sigma quality processes. The tools and order used in Six Sigma require a process to be in place and functioning. DFSS has a different objective: that of determining the needs of customers and the business, and driving those needs into the product solution created.

DFSS uses systems engineering techniques to avoid process problems at the outset. These techniques include tools and processes to predict, model and simulate the product delivery system as well as the analysis of the developing system life cycle itself.

DFSS is largely a design activity requiring specialized tools including: Quality function deployment, Axiomatic design, TRIZ, Design for X, Design of experiments (DOE), Taguchi methods, Tolerance design, and the Response surface methodology. While these tools are sometimes used in the classic DMAIC Six Sigma process, they are uniquely used by DFSS to analyze new and unprecedented systems/products.

Roles

Six Sigma identifies five key roles for its successful implementation.

• Executive Leadership includes CEO and other senior management. They are responsible for setting up a vision for Six Sigma implementation. They also empower the other role holders with the freedom and resources to explore new ideas for breakthrough improvements.
• Champions are responsible for the Lean Six Sigma implementation across the organization in an integrated manner. The Executive Leadership draws them from the upper management. Champions also act as mentor to Black Belts.
• Master Black Belts, identified by champions, act as in-house expert coach for the organization on Lean Six Sigma. They devote 100% of their time to Lean Six Sigma. They assist champions and guide Black Belts and Green Belts. Apart from the usual rigor of statistics, their time is spent on ensuring integrated deployment of Lean Six Sigma across various functions and departments.
• Black Belts operate under Master Black Belts to apply Lean Six Sigma methodology to specific projects. They devote preferably 100% of their time to Lean Six Sigma. They primarily focus on Six Sigma project execution, whereas Champions and Master Black Belts focus on identifying projects/functions for Lean Six Sigma.
• Green Belts are the employees who take up Lean Six Sigma implementation along with their other job responsibilities. They operate under the guidance of Black Belts and support them in achieving the overall results.

[From http://en.wikipedia.org/wiki/Six_sigma]