In: Statistics and Probability
Consider the piston ring data in the following table. Assume that specifications are 74.00 ± 0.035 mm. Estimate the process capability (Cp and Cpk) using:
Convert the Cp found above into approximate dpm.
Inside Diameter Measurements (mm) for Automobile Piston Rings
|
Sample |
ID |
|
1 |
74.03 |
|
1 |
74.002 |
|
1 |
74.019 |
|
1 |
73.992 |
|
1 |
74.008 |
|
2 |
73.995 |
|
2 |
73.992 |
|
2 |
74.001 |
|
2 |
74.011 |
|
2 |
74.004 |
|
3 |
73.988 |
|
3 |
74.024 |
|
3 |
74.021 |
|
3 |
74.005 |
|
3 |
74.002 |
|
4 |
74.002 |
|
4 |
73.996 |
|
4 |
73.993 |
|
4 |
74.015 |
|
4 |
74.009 |
|
5 |
73.992 |
|
5 |
74.007 |
|
5 |
74.015 |
|
5 |
73.989 |
|
5 |
74.014 |
|
6 |
74.009 |
|
6 |
73.994 |
|
6 |
73.997 |
|
6 |
73.985 |
|
6 |
73.993 |
|
7 |
73.995 |
|
7 |
74.006 |
|
7 |
73.994 |
|
7 |
74 |
|
7 |
74.005 |
|
8 |
73.985 |
|
8 |
74.003 |
|
8 |
73.993 |
|
8 |
74.015 |
|
8 |
73.988 |
|
9 |
74.008 |
|
9 |
73.995 |
|
9 |
74.009 |
|
9 |
74.005 |
|
9 |
74.004 |
|
10 |
73.998 |
|
10 |
74 |
|
10 |
73.99 |
|
10 |
74.007 |
|
10 |
73.995 |
|
11 |
73.994 |
|
11 |
73.998 |
|
11 |
73.994 |
|
11 |
73.995 |
|
11 |
73.99 |
|
12 |
74.004 |
|
12 |
74 |
|
12 |
74.007 |
|
12 |
74 |
|
12 |
73.996 |
|
13 |
73.983 |
|
13 |
74.002 |
|
13 |
73.998 |
|
13 |
73.997 |
|
13 |
74.012 |
|
14 |
74.006 |
|
14 |
73.967 |
|
14 |
73.994 |
|
14 |
74 |
|
14 |
73.984 |
|
15 |
74.012 |
|
15 |
74.014 |
|
15 |
73.998 |
|
15 |
73.999 |
|
15 |
74.007 |
Solution:

Overall Range = Average of all Ranges = 0.022733
Overall Standard Deviation in this regard is: 0.00537
Calculations:

Part B:
Standard Deviation Case
Here,
CPK = 2.131
So there will be 0 DPM in this regard.
Refer the chart given below...
Range Case
Here,
CPK = 0.504,
So, there will be close to 500000 DPM in this regard.
Refer the chart given below for reference...

End of the Solution...,