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IES331 Quality Control
Chapter 7: Process and Measurement System Capability Analysis
Example1: Gauge Capability Analysis
Ten parts are measured three times by the same operator in a gauge capability study. The
data are shown here:
Part
Number
1
2
3
4
5
6
7
8
9
10
a)
b)
c)
d)
1
2
3
100
95
101
96
98
99
95
100
100
100
101
93
103
95
98
98
97
99
100
98
100
97
100
97
96
98
98
98
97
99
Describe the measurement error that results from the use of this gauge
Estimate total variability and product variability
What percentage of total variability is due to the gauge?
If specifications on the part are at 100 ± 15, find P/T ratio, signal-to-noise ratio,
and discrimination ratio and comment on adequacy of the gauge.
Example2: Specification limits for assembled parts
Two parts are to be mated (inserted). Part A is a shell with diameter mean of 20 and
the standard deviation of 0.3. Part B is an insert with diameter mean of 19.6 and the
standard deviation of 0.4. The specification of the clearance between mating parts are
0.5 ± 0.4. What fraction of assemblies will fail to meet specifications if assembly is at
random?