A new machine has just been installed to cut and rough-shape large slugs. The slugs are
then transferred to a precision grinder. One of the critical measurements is the outside
diameter. The quality control inspector randomly selected five slugs each half-hour, measured
the outside diameter, and recorded the results. The measurements (in millimeters)
for the period 8:00 A.M. to 10:30 A.M. follow.
Time
Outside Diameter (millimeters)
1
2
3
4
5
8:00
87.1
87.3
87.9
87.0
87.0
8:30
86.9
88.5
87.6
87.5
87.4
9:00
87.5
88.4
86.9
87.6
88.2
9:30
86.0
88.0
87.2
87.6
87.1
10:00
87.1
87.1
87.1
87.1
87.1
10:30
88.0
86.2
87.4
87.3
87.8
a. Determine the control limits for the mean and the range.
b. Plot the control limits for the mean outside diameter and the range.
c. Are there any points on the mean or range chart that are out of control? Comment on the charts.