A process at a manufacturing plant produces a two-layer film. Each layer thickness is measured by a properly calibrated measuring device. The first layer has a target mean specification of 0.055 in. and the second layer has a target mean specification of 0.030 in. The combined finished product has specifications of 0.085 in. + 0.005 in. The following data were obtained from measurements of each layer individually. Four samples were taken each hour for 30 hours.
a. Assume that the processes used to produce each layer component are stable and predictable. Use the raw data (120 data points) for each component layer to estimate the respective layer standard deviation and variances. What is the estimated variance of the resultant product? Is the resultant product capable?
b. Estimate the percentage of layered films that will be outside the specification limits.
c. What needs to done to re-center or re-target the components so that the composite product (layer film) production is on target.
d. If the suggestions in part c can be achieved, estimate the total percentage of output that would be outside the specification limits
e. If the suggestions in part c can be achieved, how much would the variance of Layer 1 have to be reduced in order to meet the composite specifications in the plus/minus 3 sigma sense?