4. Suppose the polymer-coating machine currently provides the following results:

Calculate the process capability ratio (Cp) for both the temperature and the thickness variables. Is the polymer-coating process able to meet the engineering standards 99.7% of the time? Explain. Overall, Steve Edwards, Vice President of Marketing at Dittenhoefer’s Fine China, is very pleased with the success of his new line of Gem-Surface china plates. Gem-Surface plates are different from regular china in that the plates have a special polymer coating that makes them highly resistant to chipping and fading. Not only are the plates more durable, but also they are completely dishwasher safe.
In order to manufacture the new plates, Dittenhoefer’s has leased a special machine to apply the coating and has put in place a drying system to “cure” the coating on the plates.
The research and development (R&D) lab has determined that in order to prevent defective plates, it is important that the machine apply the polymer coating at the proper temperature and in the proper thickness. Specifically, R&D has written up the following guidelines:
Coating thickness. The optimal polymer coating thickness is 4 microns. If the coating is 5 microns, the plates will take too long to dry. If the coating is Coating temperature. The polymer coating needs to be applied at a temperature between 160 degrees Fahrenheit and 170 degrees Fahrenheit, with the target temperature being 165 degrees Fahrenheit. If the temperature is lower than 160°, the polymer will not adhere properly and will flake off. If the temperature is higher than 170°, the polymer coating will fade the design on the plates.

Transcribed Image Text:

VARIABLE PROCESS MEAN Temperature 165 degrees Thickness 4 microns PROCESS STANDARD DEVIATION 2.55 degrees 0.42 micron