Six sigma method is engineering solution to zero defect movement started by Phil Crosby.
Zero Defects is the approach to quality that was developed and promoted by the guru Philip B. Crosby in his book ‘Quality Is Free’.
It’s a way of thinking about quality that doesn’t tolerate errors or defects and continually strives to improve processes and prevent errors so that work is always done correctly without needing repetition or rework or generating waste;
The accepted theory was that a certain level of defects is seen as normal or acceptable, as implied by the Acceptable Quality Limit approach; Crosby took a strong line against AQLs for precisely that reason, he saw them as a “commitment, before we start the job, that we will produce imperfect material”.
Zero Defects is based on four key principles:
Quality is simply conformance to requirements.
It is always cheaper to do the job right the first time than to correct problems later
Quality is measured in monetary terms (the price of non-conformance)
The performance standard for a process must be Zero Defects.
The key word for achieving Zero Defects is Zero defects production. Not reworking to correct errors of deviations.
The case for Zero Defects
Crosby explains that defects result in costs which can be measured - inspection, waste/scrap, rework, lost customers, etc. By eliminating defects these costs are sufficiently reduced that the savings more than pay for the quality improvement programme; hence his assertion that ‘Quality is Free’ and his advocacy of the quality management movement.
As with many areas of quality management it’s about the philosophy and the journey you take from where you are now to being a better business, it is the “attitude of defect prevention”.
When your goal is zero defects it sets a standard against which all your processes can be assessed. It’s about continually striving to work better and not being satisfied with the status quo.
Crosby gave a 14 step quality improvement programme.
Lockheed Martin - Proud of Phil Crosby and Zero Defect Program
It was at the Martin Company’s Orlando plant that a far-reaching and influential program was born: Zero Defects, the granddaddy of nearly every quality control program in the world.
One of the plant’s first jobs was the production of the first Pershing missile for the United States Army. Philip Crosby was the quality control manager on the Pershing missile program, and he established the four principles of Zero Defects:
1) Quality is conformance to requirements,
2) Defect prevention is preferable to quality inspection and correction,
3) Zero Defects is the quality standard, and
4) Quality is measured in monetary terms—the Price of Nonconformance.
Put simply, it’s better to do it right the first time than to have to correct mistakes later. Crosby’s standards were credited with a 25 percent reduction in the Pershing missile program’s overall rejection rate, and a 30 percent reduction in scrap costs. Zero Defects meant a better product, produced more economically.
The Martin Company offered Zero Defects freely to all other aerospace companies and, years later, it was adopted by automobile manufacturers around the world.
Zero Defects was the guiding principle behind Martin Marietta’s work on the Titan rocket series, which propelled NASA’s Gemini astronauts into orbit over ten months in 1965 and 1966. The end result was a program that launched ten manned missions and had a 100 percent success rate—a feat unmatched in space travel before.
More articles by me on Six Sigma
The Certified Six Sigma Black Belt - Donald Benbow and T.M. Kubiak - Book Information
Six Sigma - Introduction
Total Quality Management: Focus on Six Sigma - Review Notes
Control of Variation in Inputs and Outputs - Management Insights from Statistics