Discussion:
Control chart for Kane on concentricity
Kane (1986) discusses the concentricity of an engine oil seal groove. Concentricity measures the cross-sectional coaxial relationship of two cylindrical features.
In this case, he studied the conccntricity of an oil seal groove and a base cylinder in the interior of the groove. I-le measures the concentricity as a positive devia- tion using a dial indicator gauge. Historically, this process has produced an aver- age concentricity of 5.6 with a standard deviation of 0.7. To monitor this pro- cess, he periodically takes a random sample of three measurements. The mean concentricities for 20 subgroups follow. The data are in consecutive order, read- ing across the rows. The first observation is 5.48, the second is 5.83, and so on.
5.48 5.83 6.69 6.04 5.64 5.23 4.89 5.72 5.39 6.1 9
5.78 5.76 5.82 5.63 5.73 5.05 4.62 5.74 6.60 6.81
Calculate the appropriate control limits and plot the control chart.