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Original Date: 05/08/1995
Revision Date: 01/18/2007
Information : Computed Radiography
In September 1994, McDonnell Douglas Aerospace (MDA)-St. Louis installed and began using the Fuji AC-2 Computed Radiography (CR) equipment. The company had historically been applying Nondestructive Testing (NDT) and evaluation techniques and had relied primarily on X-ray and ultrasonic methods in parts evaluation. Although these methods worked well, they did not provide the desired fidelity of data under certain circumstances such as identifying titanium flange and composite layup bondline integrity.
CR technology is based on a filmless process which utilizes a reusable phosphorus image plate as the sensing mechanism. Like film, the image plate is placed near the specimen and exposed. Following exposure, the latent image is extracted from the image plate by the main image reading system. The image reader then digitizes the image plate’s response and assembles a data file or frame. The complete process requires 1.5 minutes, in contrast to film processing which requires 8.5 minutes, and can be repeated every 15 seconds. Once read, the image plate is erased and may be reused. The digital data file produced by the reader is exported to an off-line imaging workstation where the CR data can be analyzed and stored.
CR represents feasible alternatives to industrial film for a significant number of inspection applications in the NDT labs at MDA-St. Louis. With the CR system, NDT setup time and cost is reduced, film handling and archiving are eliminated, film developing cost is eliminated, and environmental concerns of film processing are eliminated.
This technology has high utility, facilitates digital archiving of data, and allows magnification of associated images for easy inspection of critical features. The value of radiographic analysis is renewed because of the utility of CR data and a high degree of confidence in this radiographic technique. Future plans at MDA-St. Louis include the formation of a NDT common database which incorporates CR data, ultrasound-C-scan data and rejection report data. Easy access to this common database will be provided to customers in satellite locations via remote communications.
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