The data in the following table were the result of an experiment to determine the effect that three factors—holding pressure, booster pressure, and screw speed—had on part shrinkage in an injection molding process. The data in the table are coded values of part shrinkage.

(a) Analyze the data to determine the important effects.

(b) Within the bounds of the study, which settings of the three factors minimize shrinkage?

(c) Based on the analysis in (b), suggest another design to see whether better settings can be found.

(d) Assume that uniformity of the parts is the goal, with minimum shrinkage a secondary objective. Also assume that the inability to keep holding pressure constant during operation is a major cause of variation in the dimension of the parts. Choose settings to increase uniformity of the parts by desensitizing the process to variations in holding pressure.

Transcribed Image Text:

Holding Pressure + Booster Booster Screw Pressure Pressure Speed + + 21.9 15.9 22.3 17.1 20.3 16.7 21.5 17.5 (2) (8) (1) (6) 16.8 14.0 27.6 24.0 + 15.4 15.0 27.4 22.6 (7) (3) (5) (4)