Factors for calculating three-sigma limits for the

x-chart and R-chart

Size of Sample (n)	Factor for UCL and LCL for x-chart ( A2)	Factor for LCL for R-Chart ( D3)	Factor for UCL for R-Chart ( D4)
2	1.880	0	3.267
3	1.023	0	2.575
4	0.729	0	2.282
5	0.577	0	2.115
6	0.483	0	2.004
7	0.419	0.076	1.924
8	0.373	0.136	1.864
9	0.337	0.184	1.816
10	0.308	0.223	1.777

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 8.30 and for the mean range at 0.31 mm. The process is in control, as established by samples of size 6. The upper and lower specifications for the diameter of the rollers are (8.30 +0.25) and (8.30 -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 mm and the LCLR equals mm. (Enter your responses rounded to two decimal places.)