Six Sigma Process Quality
Printed From: One Stop Testing
Category: Quality Assurance @ OneStopTesting
Forum Name: Quality Methodologies / Streams @ OneStopTesting
Forum Discription: Any Good Testing Engineer must know about All the Quality Certifications & Methodologies like ISO, IEEE, CMM, PCCM, CMMMi, XP, Agile and many more.
URL: http://forum.onestoptesting.com/forum_posts.asp?TID=719
Printed Date: 16Nov2024 at 7:30pm
Topic: Six Sigma Process Quality
Posted By: satabdi
Subject: Six Sigma Process Quality
Date Posted: 05Apr2007 at 4:49am
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In 1985, Bill Smith at Motorola demonstrated a correlation between how often a product was repaired during manufacture and its life in the field. Defect levels in the parts per million (ppm) rather than in parts per hundred (%) were needed to improve the reliability of semiconductors and electronic products in order to compete with the Japanese. Hence, the development of the Motorola Six Sigma quality program with its landmark quality level of 3 ppm defects.
The process mean will vary each time a process is executed using
different
equipment, different personnel, different materials, etc. The
observed
variation in the process mean was ± 1.5 sigma. Motorola
decided a design
tolerance (specification width) of ± 6 sigma was
needed so that there will
be only 3.4 ppm defects -- measurements outside
the design tolerance. This was
defined as Six Sigma quality.
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Six Sigma was intended to improve the quality of processes that are
already
under control -- major special causes of process problems have
been removed.
The output of these process usually follows a Normal
distribution with the
process capability defined as ± 3 sigma.