Page 97 - Six Sigma for electronics design and manufacturing

Six Sigma for Electronics Design and Manufacturing
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engineers are responsible for setting the specification limits for new
products as broad as possible and still permit the proper functioning
of the product. Manufacturing engineers have to narrow the manu-
facturing process distribution, as measured by the standard devia-
tion of the product characteristics. This can be achieved by more fre-
quent maintenance schedules, improving incoming inspection
methods, working with suppliers, increased operator training, and
performing design of experiments (DoE) to reduce the variability of
the process.
The formal definitions of six sigma and other quality measuring
systems such as Cp and Cpk were introduced. In addition, their rela-
tionship to determining the defect rate and examples of calculations
were also shown, from both variable and attribute manufacturing
processes. An important part of these quality systems is the under-
standing of the assumptions underlying each system. The choice of
the proper system should be compatible with the type of business the
enterprise is engaged in and its competition.
The assumption that all manufacturing and supply data are nor-
mally distributed was examined, and methods to prove normality
were shown. In the case of nonnormality, alternate methods for trans-
forming data to normal distribution, performing six sigma calcula-
tions, and then converting the data back to the original distribution
were also shown.
2.6 References and Bibliography
Bowker A. and Lieberman G. Engineering Statistics. Engelwood Cliffs, NJ:
Prentice-Hall, 1972.
Box, G. and Hunter W. Statistics for Experimenters. New York: Wiley, 1978.
Burr, I. Engineering Statistics and Quality Control. New York: McGraw Hill,
1953.
Chan, L. et al. “A New Measure for Process Capability: Cpm.” Journal of
Quality Technology, 20, 3, 162–175, July, 1988.
Clausing D. and Simpson H. “Quality by Design.” Quality Progress, January
1990, 41–44.
Crosby, P. Quality Is Free. New York: McGraw Hill, 1979.
Deming, Edwards. Quality, Productivity and Competitive Position. Published
video lectures and notes. MIT Center for Advanced Engineering Studies.
1982.
Devore, J. Probability and Statistics for Engineering and the Sciences. Bel-
mont, CA: Brooks/Cole, 1987.
Dixon W. and Massey, F. Introduction to Statistical Analysis. New York: Mc-
Graw Hill, 1969.