Current Quality Culture Mini Paper
Six Sigma Quality Control
By:
Shawn Higbee
Steve Soseman
Kaya Tolon
"In the past, customers were happy if 99.5 percent of the parts you gave them worked with
no problem. Now world-class companies want only 200 rejects for every million parts and,
ultimately, they want zero."
-
John Bertrand, President, A.O. Smith Electrical Products Company
What is Six Sigma?
Six Sigma (6σ) is the name of the methodology used to achieve a minimum number of defects in
manufactured products or mistakes in service transactions. Historically speaking, the 6σ method
was a statistical expression created by Phillip Crosby as a synonym for a quality control standard
that was so rigid that it would virtually eliminate defects in manufactured goods
(www.sixsigma.de/english/index_eng.htm). It was first implemented by Motorola in 1985 as a
means to improve the quality of their products and services. In the first nine years of its use by
Motorola, it was responsible for over $2 billion in bottom-line savings
(www.mpcps.con/SIX0.html).
So what exactly is 6σ quality control…? It is quality control standard, which essentially
eliminates defects in products and services. The lower-case Greek letter, sigma (σ), is the
common symbol for the standard deviation of a population of values. Generally speaking, σ is a
number that quantifies the shape of the distribution of a population of values, whereas small value
of σ is synonymous with low variability and high quality. With a 6σ quality control system in
place, 99.99966% of all the parts a company produces will fall within the tolerances it sets forth.
This equates to roughly 3.4 defective products for every million produced. For all practical
purposes, this is the lowest possible number of defects possible from any manufacturing process
(www.sixsigmaqualtec.com/Products/sixsigma/success.html).
The difference between 6σ and the traditionally used 3σ quality control limits (99.73% of the
parts fall within specifications) might not seem significant, but when placed in a different context,
the fallacy of 3σ quality control becomes obvious. For example:
•
Virtually no modern computer would function.
•
10,800,000 healthcare claims would be mishandled each year.
•
18,900 US Savings bonds would be lost every month.
•
54,000 checks would be lost each night by a single large bank.
•
4,050 invoices would be sent out incorrectly each month by a modest-sized
telecommunications company.
•
540,000 erroneous call details would be recorded each day from a regional
telecommunications company.
•
270,000,000 (270 million) erroneous credit card transactions would be recorded each
year in the United States.
Source: http://www.qa-inc.com/knowledgecente/articles/SixSig_pg140-2.html
Is Six Sigma good for every company?
The benefits of implementing a 6σ include increased productivity, reduced waste, and higher
profit margins. In reality, companies that utilize three or four sigma spend about 15% of their
revenues fixing defects on returned products
(www.sixsigmaqualtec.com/Products/sixsigma/index.html). By tightening their quality
standards, companies can add tremendously to their profit margins and boost their bottom line
profits. As tempting as these benefits are, a 6σ program may not be right for all companies.
Small companies might find it prohibitive to significantly upgrade their systems to the point
where they are able to produce products at the 6σ level. Additionally, it costs a minimum of
$5,000 for the training and can require up to a month to train one employee in 6s standards and
procedures (A "6σ Black Belt" is the popular term for those who have been through the training).
These costs can be prohibitive in many smaller companies. Especially for companies that are in
non-competitive, non-evolving fields or if they deal with a small customer base that does not
demand significantly higher levels of quality.
Applying Six Sigma:
In order for a company to adopt a Six Sigma methodology their first and foremost step should be
a commitment by the top executive leaders of the company. This is done to insure that the process
is not just a technical method undertaken by engineers; rather it involves changing the way the
entire company views the needs of their customers and the level of quality they are capable of
producing.
According to Advanced Systems Consultants’ (ASC) – the first consulting firm to implement a
6s Program, after having presented the executives with their strategy, they prepared 6s
performance indices, identifying the critical business issues of the company. They then classified
the processes according to their impact on the customer-defined issues and indices. Next they
defined projects and built teams (the leaders of which were "6σ Black Belts", and their members
" 6σ Green Belts"), which were then tasked with the control of and optimization the company's
processes. Then a periodic review by each team was done and the 6s performance studied.
Finally, the improvements were institutionalized and uniform standards were set throughout the
company.
This program uses a sound engineering approach to improving product quality and reducing
waste. It has applications to technical processes and to many service related fields. Whether it be
in a consulting firm or a financial institution, 6s Black Belts are the technical implementers of 6s
quality standards and will continue to expand these techniques to new industries.
References:
Advanced Systems Consultants (ASC): http://mpcps.com/SIX0.html
(American Society for Quality, ASQ: http://www.asq.org/products/sigma/index.html
Motorola University: http://mu.motorola.com/SixSigma/SixSigma.html
Six Sigma Academy: http://www.6-sigma.com/do.html
Six Sigma Program: http://www.mpcps.com/SIX0.html
Six Sigma Success: http://www.sixsigmaqualtec.com/Products/sixsigma/success.html
Six Sigma Training: Implement proven, leading-edge six sigma methodologies:
http://www.sixsigmaqualtec.com/Products/sixsigma/index.html
Knowledge Center: http://www.qa-inc.com/knowledgecente/articles/SixSig_pg140-2.html