Question

Samples ofn-6 items each are taken from a manufacturing process at regular intervals. A normally distributed quality characteristic is measured, and X and S values are calculated for each sample. After 50 samples, we have 50 50 X, = 1000 S,-75 and a) Compute the control limits for the Xand S control charts. b) Assume that all points on both control charts plot within the control limits computed in part (a). What are the natural tolerance limits of the process? c) If the specification limits are 19-4.0, what are your conclusions regarding the ability of the process to produce items within these specifications? d) Assuming that if an item exceeds the upper specification limit it can be reworked, and if it is below the lower specification limit it must be scrapped, what percent scrap and rework is the process producing? e) If the process were centered at u-190, what would be the effect on percent scrap and rework?

Answer 1