What is Six Sigma?

What is Six Sigma?

Six Sigma is a set of tools used to control business processes by reducing defects and improving quality. It is based on the idea that defects result from deviation and that, therefore, there should be no more than six sigma (standard deviations) between a process and its norm. The value of six sigma represents 3.4 defects for one million manufactured products!
Six Sigma involves understanding customer needs, analyzing data, and improving processes.


In what areas do we apply 6 Sigma?

Although the most common examples of 6 Sigma refer to improving the quality of a product in a processing or manufacturing environment, 6 Sigma applies in every operational field. Troubleshooting tools and methods can be applied from the design phase to the warranty and even in support service areas.

The main goal of 6 Sigma is to reduce variation in a process. If the variation of a process is small, this process can better meet customer expectations.

To reduce variation, the team needs to understand how inputs change or outputs vary. This relation is represented by the mathematical equation; y = f (x), where y is the output, x represents the inputs, and f represents the function or relationship between the two.

In what situations do we use 6 Sigma?

In reality, not all problems can be treated with the same quality tools. In fact, it has been observed that most problems tend not to be very complex or difficult to solve. These types of problems can be solved using the PDCA cycle, because the root cause is known or easy to determine. But, there are also problems in which the cause of the root is not known and is not easy to determine.
These problems, although fewer in number, often cause the largest amount of scrap parts, as they persist for a long time and require additional operations, such as inspection and reprocessing of non-compliant products.
To solve these problems requires additional tools and different methodologies, such as those contained in the 6 Sigma-DMAIC method. But, all these problem-solving tools and specific methods are found in the set of tools of the production systems of the industrial groups, because they represent ways to reduce costs and achieve operational excellence.


What is the methodology for implementing Six Sigma? What is DMAIC?

-Who are the customers and what are their priorities?
A Six Sigma team identifies a suitable project, based on operational objectives, as well as customer needs and feedback received from them.
Also at this stage, the team identifies those characteristics, called CTQ – “critical to quality” (essential characteristics for quality), which the client considers vital.

-How is the process measured and how is it carried out?
The team identifies the essential factors of the internal processes, which influence the CTQ and measures the defects resulting from those processes.

-What are the most important causes of defects?
The team finds out why the defects occur by identifying the key variables
which most likely produce process variation.

-How do we eliminate the causes of defects?
The team confirms the key variables and measures their effects on the CTQ, then identifies the maximum acceptable limit of the key variables and validates a system for measuring the deviations (G) of the variables. The team modifies the process to keep it below the maximum limit (or above the minimum limit).

-How can we maintain improvements?
Tools are installed that ensure that key variables are kept below the maximum limit over time. In some cases, the fifth step, mentioned above, should be accompanied by the “recognition” of the problem before the “definition”
and “standardization” and “integration” should be the last steps in improving the process, by permanently incorporating the solution.

What are the organizational roles in Six Sigma?

Black Belt, Green Belt, Yellow Belt, White Belt

Champions – qualified business leaders, who promote and lead the Six Sigma process is an essential department of operations;
Black Belt Masters – Qualified business leaders, responsible for strategy, training, monitoring, mentoring, deployment, and Six Sigma results;
Black belts – qualified experts, who lead process improvement teams, who deal with projects, and who guide green belts;
Green belts – provide the organization with teaching and leadership skills. They are qualified quality leaders and are responsible for the strategy, training, guidance, conduct and results of Six Sigma processes.


Six Sigma ensures knowledge and compliance with customer requirements. It uses a systematic strategy to solve problems and requires actions based on data and analysis. 6 Sigma is also effective (and) in solving complex problems with multiple root causes.
6 Sigma aims to reduce process variation
-Understanding the functions Y = f (x) (inputs-outputs / processes)
Determining the dominant source of variation
Controlling the dominant source of process variation