Question

Control charts are to be kept on the thickness measurements for a process that rolls 10-gage copper sheets. The current specification in the sheets is 0.1360+0.0020 inch. After collecting 25 samples of n 5 measurements at approximately half-hour intervals, the data were used to determine Σ L:3.421 inches and R.-0.044 inches, with i1 to 25. Assume that the quality characteristic is normally distributed a. Compute the control limits for the X and R control charts for this process (10 pts.) Ans: rChart UCL 0.1379 UCL 0.0037 R Chart CL 0.1368 CL 0.0018 LCL=0.1358 LCL= 0.0000 b. All points on both control charts fall between the control limits on part (a) What are the natural tolerance limits of the process? (5 pts.) Ans: UNTL-0.1391 NTL 0.1346 c. 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 what percent rework is the process producing? (5 pts.) Ans: 6.26% 0.01% A new process is started, and the sum of the sample standard deviations for 30 samples of size 5 is S700, with i 1 to 30. The specifications of the product are 720 ± 85 a. What are the appropriate parameters for an S control chart for this process? (5 pts.) Ans: S Chart UCL 48.74 CL 23.33 LCL = 0.00 What is an estimate of the standard deviation of the process (0)7(5 pts.) Ans: 24.82 What is the process capability ratio? (5 pts.) Ans: 1.1414 What are your conclusions regarding the ability of the process to produce items within these specifications? (5 pts.) Ans: Conclusion b. C. d.

Please answer to all parts of the problems. Do not answer if you do not get the right answer. Thank you!

Answer 1

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