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6
Process Capability Analysis at a
Manufacturing Company
This case study is about a Six Sigma project implemented by the production
manager at a manufacturing rm that produces a critical automobile part
used in cars produced by three major automobile companies. The produc-
tion manager aims to improve the capability of the manufacturing process.
Recall the following process capability ratios from Chapter 2.
=
σ
=
µ−
σ
=
−µ
σ
=
C
C
LSL
C
USL
C
6
3
3
MIN{
p
pl
pu
pk pl pu
where
USL = Upper specication limit
LSL = Lower specication limit
µ = Process mean
σ = Process standard deviation
The higher the C
p
and C
pk
values are, the better the process is.
Section 6