Plastic sheets are manufactured on your blown film line. The Cp value is 1.7. You sell the plastic sheets to your customers with specification of 2 mm ± 0.4 mm.
1. List three important assumptions you must make to interpret the Cp value.
2. What is the theoretical process standard deviation, σ?
3. What would be the Shewhart chart limits for this system using subgroups of size n = 4?
4. Illustrate your answer from part 2 and 3 of this question on a diagram of the normal distribution