(35 points) Consider an experiment to improve a heat treatment process on truckleaf springs reported in Pignatiello and Ramberg (1985). The heat treatment whichforms the camber (or curvature) in leaf springs consists of heating in a high tem-perature furnace, processing by a forming machine, and quenching in an oil bath. The height of an unloaded spring, known as free height, is an important qualitycharacteristic whose target value is 8 inches. An experimental goal is to make thevariation about the target 8.0 as small as possible.

The five factors listed in Ta-ble 1 were chosen across the various stages of the process:

(A)furnace temperature

(B)and heating time

(C) are from the heating stage, transfer time

(D) is the time ittakes the conveyer to transport the springs from the furnace to the forming ma-chine, hold-down time

(E) is the time that the springs are held in a high pressure