It’s hard to believe but the actual root of Six Sigma quality management is the bell curve, or normal curve, developed by Carl Gauss circa 1800. This curve of graphical points shows that far more of the examples in a set fall near the average (the norm), and far fewer examples are at the extremes. The key term is “normal,” because that is the basis of the ideas that became Six Sigma systems: normal should and must result in the perfect part, every time. So, under a 100-percent quality system, the most normal product of the manufacturing process is a perfect part.
Six Sigma got its name from Motorola’s Bill Smith. Intensive analysis of thousands of manufacturing processes has statistically shown that products coming off the line are expected to have six deviations from the customer’s expectations per million parts made. Sigma is a statistical symbol Smith used to name the process, which is based in these statistics.
In the mid-1980’s, Motorola refined the system for manufacturing, which is the subject we will stay with, but it has spread in the last 25 years into all divisions of business: finance, sales, customer service, logistics, reverse logistics and accounting.
Briefly, Six Sigma involves teams within (and often outside) the company finding errors in manufacturing and defects in products, and then defining why and how they happened. These teams or others then seek ways to stop or greatly reduce those circumstances from happening again. The goal is 100 percent defect-free products, which is impossible in reality but can be nearly achieved in short-run situations.
To incorporate Six Sigma, businesses gat key personnel trained in the basics, then assign individuals to get more advanced experience and training. Once trained, employees begin the process of implementation. Companies can hire Six Sigma professionals to integrate the system into the company’s manufacturing. This saves a lot of employee hours. Companies can also have a Sigma management team of their own workers whose responsibility will be to integrate the system and train other employees.
The quality system is not easy to implement. Like Total Quality Management and Zero Defects, Six Sigma in manufacturing depends on every employee buying into the idea and conscientiously looking for ways to improve his own work. Six Sigma tactics define “customer” as any person receiving the product at any stage, which includes the next employee down the line. The customer is therefore involved in total quality refinement as well.
In manufacturing, systems are not concerned only with quality but with reducing costs and operations, or becoming lean. This lean manufacturing must be incorporated with Six Sigma, not vice versa. Quality incentives, with a background of total quality management, must start with Six Sigma thinking. Six Sigma and lean manufacturing are now being integrated as one main objective for factories throughout the world.
All quality systems are based on statistical or historical achievements from past manufacturing incentives. As the quality of tools themselves, then electronic matching and finally Computer Aided Design and Manufacturing began to provide better products, customers began to expect then demand fewer defects. Six Sigma is one of these processes developed to make companies more competitive each year, while they improve each year.
Learn more about operations management in Interviews with Operations Management Masters.
Six Sigma Expert