1. Compare the test results from the production tests between the mechanical unit and the air unit. This analysis should consider both average and test variation.
a. All paper machines and grades combined - air versus mechanical
i. What is the offset between the two instruments?
ii. Does one instrument have greater variation than the other?
b. Between paper machines, all grades combined - PM1 vs PM2 vs PM3 air versus mechanical
i. What is the offset between the two instruments on PM1? PM2? PM3?
ii. How do these offsets compare to the overall offset?
c. Between basis weights on each paper machine
i. What is the offset between weights on each machine, and how does that compare to the overall offset for that machine?
d. The mill has the ability to run the same grade on multiple paper machines. Compare the relationship between the two instruments for the following (consider both average and variability):
i. 45 lb and 50 lb weights combined on PM2 and PM3 (45lb and 50lb grades are considered lightweight)
ii. 70 lb weights on PM1 and PM3
e. What do you conclude about the relationship between the instrument results in each scenario?
2. Compare the variability in test results between the current method (air instrument, 12 pops), the new mechanical unit with 12 pops, and the new mechanical unit with 6 pops. What is the impact on test variability if we reduce the number of pops down to six when we implement the new mechanical instrument? What would be the impact on test variability reported to the machines if the new mechanical instrument is put on line with an average of 6 pops versus 12? Would you recommend 12 pops instead and why?
3. Select a grade and basis weight for each machine and plot the following control charts for both the mechanical and air test results. Select a combination that has at least 25 data points. Interpret the results for each instrument. What does each type of chart tell you? Does the instrument make a difference in the perceived stability of the process?
a. Individual/moving range charts
b. The appropriate charts to assess process average and variation using a subgroup size of 12
4. The most customer-sensitive grades for ZDT are 100lb and higher basis weight products on PM1. In order to achieve adequate ZDT, the machine must attain a certain level of refining. Too little refining can hurt ZDT, while too much refining will cause runnability problems on the machine. In order to optimize both situations, ZDT limits have been established. Based on an analysis of grades greater than 100 lbs on PM1, what would the limits be for the mechanical ZDT test results if the following limits are currently in place for the air ZDT unit? Assess the process capability if the machine wants to run consistently between the upper and lower action limits using data from the new mechanical ZDT instrument.
a. Reject = 85
b. Lower action limit = 83
c. Target = 92
Upper action limit = 95