
Continuous Improvement of Quality 477
shows a plot in which there seems to be no relationship between X and Y�
Values of Y do not seem to be dependent on the values of X�
Case Study 8.5
Cores made of sand are dipped in a wash and dried in drying ovens in
a foundry� These cores should be dried enough to expel the moisture,
which strengthens the cores but over-drying will drive out the resin,
the bonding chemical, and make the cores brittle� Therefore, the drying
must be very carefully controlled� This was accomplished by control-
ling the dry- ability index of the ovens, which is an index that repre-
sents the amount of drying an oven is able to ...