General Dynamics, Inc. is a manufacturer of hydraulic machine tools. It has had a history of leakage trouble resulting from a certain fitting. Twenty five samples of machined parts were selected, one per shift, and the diameter of the fitting was measured.
a) Construct a X-bar and R charts for the data provided in the following attached file. R Chart and X-bar Chart – General Dynamics.xlsx
b) What do you think of the results?
c) If the regular machine operator was absent when sample 4, 8, 14 and 22 were taken, how will the results in part b be affected?
d) A second table in the worksheet represents measurement taken during the next ten shifts, after the operator was back. What information does this table provide to the quality control manager?