Problem 20 An automatic lathe produces rollers for roller bearings, and the process is monitored by statistical process control charts. The central line of the chart for the sample means is set at 8.90 and for the mean range at 0.38 mm. The process is in control, as established by samples of size 4. The upper and lower specifications for the diameter of the rollers are (8.90 +0.25) and (8.90 -0.25) mm, respectively. Click the icon to view the table of factors for calculating three-sigma limits for the x-chart and R.chart a. Calculate the control limits for the mean and range charts. The UCLR equals 87 mm and the LCLR equals 0.00 mm. (Enter your responses rounded to two decimal places.) The UCL; equals mm and the LCL, equals mm. (Enter your responses rounded to two decimal places.) Factors for calculating three-sigma limits for the x-chart and R-chart Factor for LCL for R-Chart (D3) 0 Size of Sample Factor for UCL and LCL (n) for x-chart (A2) 2 1.880 3 1.023 0.729 5 0.577 6 0.483 7 0.419 0.373 9 0.337 10 0.308 O O O O Factor for UCL for R-Chart (D4) 3.267 2.575 2.282 2.115 2.004 1.924 1.864 1.816 1.777 0 0.076 0.136 0.184 0.223