Figure 3. Main effects plot of DOE variables waterjacket core length.
Figure 4. Regression analysis for left bank.
The team began to narrow its focus on core dimensions and possible core shrinkage as a contributing cause for the short waterjacket length. The team developed a method to mea- sure the waterjacket cores on a CMM machine from the in- side of bore 1 to the inside of bore 4. Waterjacket cores were measured multiple times to determine repeatability. Once the team was confident of the measurement system, they be- gan to collect information on both old and new coreboxes. The team looked at uncoated cores vs. coated and new vs.
International Journal of Metalcasting/Summer 10
old cores. The cores also were weighed as an indicator of density. From an initial small sampling of waterjacket core dimensions, the data indicated the cores were shrinking ap- proximately 0.02 in. (0.5 mm), as shown in Figure 5. The casting plant consulted with its current resin and sand sup- pliers to assist with the investigation. With suppliers on the team, more extensive testing was conducted in a laboratory setting to increase the number of variables investigated with- out disrupting block production.
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