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UNDERSTANDING THE SIX SIGMA PRINCIPLE

Six Sigma: When quality control becomes an unnecessary preoccupation

Developed and espoused by Motorola in 1987, Six Sigma (6Σ) a business strategy concept and management philosophy that sets the highest standard of discipline in meeting extremely high objectives, collecting data and analyzing results to almost zero-degree of error tolerance as a way to reduce waste, defects and irregularities in both products and services.

The Greek letter sigma (Σ) is used to statistically signify the disparity from a given standard.

In statistical parlance, Six Sigma is the “nickname” of six standard deviations from the mean—which numerically translates to about two (2) defects per billion. In layman’s language, a particular manufacturing process cannot go beyond producing two (2) defects per billion parts produced. Six Sigma is, therefore, achieved only if defects are kept to an almost perfect production rate equivalent to 99.9997%. In other words, the widely used failure rate of 3.4 parts per million is already an unacceptable mathematical figure—which in reality corresponds to roughly 4.5 sigmas. (Use the Sigma Level/ DPMO calculator to compare sigma level with or without this 1.5 shift)

Since Six Sigma focuses on process quality, it is imperative to measure how many defects are in a process and thereby figure out how to systematically eliminate errors—adopt fine-tuning methods—and achieve concrete and measurable results which is close to being perfect.

Once the level of Six Sigma excellence and consistency is realized, quality control normally is no longer necessary.

The 6-Sigma characteristic

Six Sigma is a meticulous, precise and calculated analytical process for anticipating and addressing quality improvement. It is likewise an essential yardstick in solving process-related problems.

It can also be applied to a gamut of strategies, tools, formulas and methodologies to improve the profitability of companies through defect reduction, yield improvement, improved consumer satisfaction and optimum product performance.

Fitting in different ‘belts’

The Six Sigma is implemented using trained key players known as “Black Belts”, “Green Belts” and “Master Black Belt”.

The “Green Belt” is a person trained in 6-Sigma methodology who is a member of the Six Sigma process improvement action teams.

A “Black Belt”, on the other hand, is the person who is part of the leadership structure for process improvement teams. These belters are technically-oriented personnel who are highly-regarded to lead teams and advise management-level officers.

And what does a “Master Black Belt” do? Well, he or she acts as the program manager or Six Sigma director. He checks and watches over process improvement projects and provides support to Black Belts when the event requires. A Master Black Belt teaches other Six Sigma students and helps them achieve Green and Black belt status.

In Six Sigma, statistical tools usually follow the DMAIC step—or the Define, Measure, Analyze, Implement and Control charts.

Specific tools are used as control charts covering Pareto diagrams, process mapping, value stream mapping and scatter plots. In addition, Lean Manufacturing and TPM tools are used as well as Kaizen, 5S, OEE and LCC.

Can 6-Sigma do it right?

Perhaps the question should be: How important is Six Sigma?

Majority of companies around the globe typically operate at about 4-sigma precision—or nearly 99% perfection.

A 4-Sigma level would mean producing products at the rate of 6,200 defective items for every million you produce—compared to only 3.4 defectives if one is at the 6-Sigma level.

When Motorola introduced the Six Sigma philosophy, the scheme was applied to repetitive manufacturing processes. Today, it has evolved into a constant and structured process of improving all aspects of operations to consistently meet customer satisfaction in both products and services because Six Sigma is driven by the dictates of the consumers.

The Motorola approach has encouraged leanness, simplicity and the correct attitude of doing-it-right-the-first-time. Six Sigma proponents claim that they have achieved 50% process cost reduction, improved cycle-time, reduced wastage, increased customer satisfaction and maintaining production quality.

The Six Sigma way is to understand the customers’ needs, gather valuable information and data from the processes, and make accurate statistical analysis from it to improve the processes.

At the end of the day, making it to the Six Sigma level is learning from the mistakes and successful process deployments in the past, and getting the required support from co-workers and the valuable backing of top management.

If companies are able to make Six Sigma take place in their respective backyards, quality control becomes an unnecessary preoccupation—and companies will definitely have a happy, satisfied and growing customer base.

Oskar Olofsson, 2009