X-Ray CT for Quantitative Casting Material Evaluation

Casting is an economical way to manufacture parts. However, castings are rarely used as primary structure in aircraft because of the large safety factors that are required for design allowables. This conservatism in utilization is due, in part, to the traditional limitations in evaluation technology for castings. The safety factor increases the overall weight of the casting, which defeats the cost and weight savings that castings offer. Significant gains in casting utilization are possible by a combination of control of the casting microstructure and proper nondestructive evaluation (NDE) of the product. The presently applied NDE criteria for accepting castings involves a comparison to a qualitative standard and has very little to do with their ability to provide operational service. Computed tomography is an enabling technology whose measurements can be used to quantify the product quality level and improve the consistency of casting manufacture.