The management of a dried milk manufacturer wanted to evaluate the process capability of its packaging lines. A can line was studied for weight of filled cans. The specification is 974 grams plus or minus 14 grams (including the weight of the can itself). Thirty-five samples of six cans were weighed, and sample mean and range were calculated. The process was in control. The grand mean was 975.7 grams and process standard deviation was 4.7581 grams.
a. Calculate the Cp and ratios. Is the filling line capable?
b. After changing the wearable parts of the line, including the piston cylinders, 46 samples of 6 cans were weighed. The grand mean was 976.19 grams and process standard deviation was 2.891 grams. Calculate the new values of Cp and Cp* ratios. Has tire filling line become capable?