ISYE 315 DISCUSSION 8 (Ch. 13 SPC and Process Capability)
np-chart (number of defectives)
d = np = # of defectives
Using the data from the above problem, compute the control limits for the np-chart. Is the process
in control? Use 3 sigma control limits.
Is the process in control?
#3. c-chart (average number of defects in a sample)
In a sample of n items, c is the total number of defects in the sample
The Woodland Paper Company produces paper for the newspaper industry. As a final step in the
process, the paper passes through a machine that measures various quality characteristics. When the
process is in control, it averages 20 defects per roll.
Setup a control chart limits for the number of defects per roll. Use 3 sigma control limits
The first two rolls contained 27 and 5 defects, respectively. Is the process in control?