Introduction to Six Sigma – Concepts and Principles
Six Sigma is a statistical quality control mechanism that aims to achieve a maximum of 3.4 defects per million opportunities in any manufacturing process. Six Sigma was pioneered at Motorola in the 1980s with the initial goal of measuring defects that occur in the manufacturing process and minimizing them. This process helped Motorola save a great deal of money. Later, Six Sigma was also used at General Electric to achieve similar results. Today, Six Sigma is being implemented in almost every organization; in your financial, operational or production process to achieve dramatic improvements in them and therefore improve profits. Since Six Sigma led to high levels of customer satisfaction, it is being used in a variety of industries, be it telecommunications, healthcare, insurance, or software.
The term Six Sigma is derived from statistics. Sigma is a Greek symbol used to denote a standard deviation or variation from the mean or average in common parlance. The principle behind Six Sigma is to measure variations from the average and therefore try to control them. In a production process, this concept would translate into a process for measuring defects and controlling them with the aim of guaranteeing a defect-free production process.
Any Six Sigma project focuses on achieving radical improvement in a systematic way by managing defects and variations in any manufacturing process or service transaction. To accomplish this, experts typically take two approaches:
- The DMAIC Framework
- DFSS model
The DMAIC framework is used to make a process that works reasonably well even better. DMAIC is an acronym for Define, Measure, Analyze, Improve and Control. In the DEFINE stage, goals are defined based on critical parameters; either critical for quality or critical for production. These goals are derived from customer requirements. In the MEASURE stage, current performance related to service or production is measured against goals. In the ANALYZE stage, the current performance is studied to analyze the causes of variations or defects. In the IMPROVE stage, variations or defects are reduced. In CONTROL, action is taken to control future performance.
The DFSS model is implemented when there is no quality control process or the process is not effective at all. DFSS stands for Design for Six Sigma, which includes the following steps:
- IDENTIFY – Target identification based on critical parameters, industry benchmarks and customer requirements
- DESIGN – Weigh possible improvement solutions and decide on the best
- OPTIMIZE: Optimize performance by implementing statistical modeling techniques and refining processes with them
- VALIDATE – Validate those designs that are in accordance with the objectives of the process
Many times, it can happen that a project that could have started with the DMAIC framework is changed to a DFSS model because experts feel that a complete redesign is needed.
Depending on their level of experience, experts on a Six Sigma project are called Belts. A yellow belt is at the lower end of the skill spectrum, followed by the green belt, followed by the black belt, and finally the Master Black Belt, who is a mentor or coach to the other belts.