Quality system design | n/a

 Need questions 7, 9, and 10 answered. Thanks!

7. The data represents the copper concentration in a plating process. Copper concentration in a plating pool is controlled by an automated colorimeter that takes readings and adjusts the concentration as required. To verify the correct functioning of a new colorimeter system, copper concentration is measured manually six times per shift. 

(a) Plot an x-bar and R control chart for this process. Perform runs tests to Western Electric. Is the process in control? Revise the control limits as necessary.

(b) Estimate the mean and standard deviation of the revised process. 

(c) Is the layer thickness of the revised process normally distributed?

(d) If the specifications are 9.0  2.0 ppm, estimate the process capability. 

 9. For the data in problem 7, the target copper concentration ppm is 9.0.

 (a) Estimate the process standard deviation from the control charts in problem 7. 

(b) Create a tabular CUSUM chart for this process, using standardized values h = 5 and k = ½. (c) Interpret the CUSUM chart. 

10. Create an EWMA control chart for the problem 7 copper concentration ppm data using λ = 0.1 and L = 2.7. Interpret the EWMA control chart in comparison to the CUSUM chart. 

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