Statistical Process Control Charts.

Operators at a plant that produces hydraulic pumps collected the following data on seal groove depth. Use these data to plot Average and Range charts. The company uses a mean depth of .067 for plotting sample means with an upper control limit of .0677 and a lower control limit of .0663. It uses a mean range of .0012 with an upper control limit of .0024 and a lower control limit of 0.

Sample# Sample Values in Thousandths 1 67 67 68 67 67 2 68 68 68 68 68 3 69 68 68 68 69 4 68 68 68 68 67 5 67 67 66 67 67 6 67 67 67 67 67 i, 67 68 66 68 67 8 69 68 68 68 68 9 66 67 67 66 67 10 67 67 68 67 67 11 68 67 67 68 68 12 66 67 67 66 67 13 67 67 66 67 68 14 67 67 68 67 66 Required:

a. Create a process control chart for the average groove depth.

b. Create a process control chart for the range of each sample.

c. Identify any samples that fall outside the control limits.

d. Describe any significant trends you see in the graphs.

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