Besides the cost advantage, casting allows designers to incorporate features like small radii to enhance the integrity and performance of the part. Designers and manufacturers met repeatedly during the design process. Among the things the group discussed were materials for the door, wall thickness, tolerances, and contour control. Once the doors were made, close dimensional checking and straightening in a unique fixture ensured that they would fit properly in their frames and thus meet thei cost and performance constraints. One of the main concerns of the design team was maintaining the door's strength while adding louvers to it.
Vented door is a net-shaped part ready for assembly.
The only parts that require post-casting machining are the hinge lugs at the bottom. Since the designers wanted to limit machining to that which was required for assembly, they had to come up with a reliable way to inspect the casting. They decided to provide target points from which critical features could be measured using geometrical tolerancing. For example, to check the door's edge profile, Grumman engineers made a plaster cast of a door that fit in the existing access-door frame. If a door edge fell outside the tolerance limits, it was straightened with a fixture developed by the manufacturer.