Fujiyama Electronics, Inc. has had difficulties with circuit boards purchased
from an outside supplier. Unacceptable variability occurs between two drilled
holes that are supposed to be 5 cm apart on the circuit boards. Thirty samples
of four boards each were taken from shipments from the supplier as shown in the
data from the worksheet below. Data in the worksheet below can also be accessed
in Doc Sharing in a file named Fujiyama Electronics Sample Data.
Fujiyama Electronics
Observations
Sample 1 2 3 4
1 4.92 4.26 4.94 4.29
2 4.65 5.54 5 5.42
3 5.77 5.26 4.76 4.79
4 6.25 4.88 5.66 4.44
5 5.27 5.41 6.02 4.91
6 5.22 5.38 5.08 4.65
7 5.47 4.68 4.56 4.7
8 5.71 4.54 4.17 4.87
9 5.24 5.58 4.72 5.41
10 4.42 5.18 4.79 4.73
11 5.14 4.26 4.71 5.48
12 4.92 5.78 5.5 5.05
13 5.79 3.83 4.3 4.78
14 4.92 4.8 4.75 5.59
15 5.68 5.74 4.65 5.2
16 5.43 4.81 5.27 4.96
17 4.79 6.04 4.47 5.18
18 4.43 5.08 3.69 6.43
19 6.35 5.95 6.29 5.89
20 5.03 4.66 5.25 4.46
21 6.32 6.09 5.57 5.91
22 4.3 5.47 4.27 4.34
23 6.07 4.97 5.51 5.02
24 5.11 4.9 5.91 4.66
25 4.5 5.24 4.86 4.35
26 4.91 4.79 5.74 5.03
27 4.65 4.71 4.81 5.32
28 4.7 5.5 6.04 4.3
29 5.87 5.3 5.78 5.07
30 4.41 4.75 4.95 5.11
Calculate X-Bar-Bar, R-Bar, and associated control limits using the data in the
table above.
Create X-Bar•R (Average & Range) Control Charts from the data in the table
above.
Discuss notable out-of-control conditions displayed in the completed X-Bar•R
(Average & Range) Control Charts. Only consider points outside the control
limits. Do not consider runs, set of points within certain zones, and so forth.
If the conditions you note could be defined as assignable conditions, and they
are removed from the process, then what will happen to the X-Bar•R Control
Chart?
Remove the data related to the out-of-control points you observed from the
original data, and recalculate new X-Bar-Bar, R-Bar, and associated control
limits.
Create new X-Bar•R (Average & Range) Control Charts from your updated data.
Discuss how the two sets of Control Charts are different. What has changed?
