Radiography Inspection Method through CR

 

If there is one thing in life we can always be certain of, it is change and the constant evolution of technology. Change is not something we should fear, rather embrace; this is especially true in technology. In recent years the technology used in the Radiography Inspection method has gone through some phenomenal changes. The NDT industry is becoming more acclimated in using Digital Radiography techniques including (CR) Computed Radiography, (DDA) Digital Detector Array, and even (CT) Computed Tomography. When these technologies are performed with proper techniques, they have been proven to have better probability of detection than film.   Recently, we have experienced an increase in customer demands, across all industries, promoting the change from film to a non-film CR process.

Radiography Inspection

The CR Process

Rather than using expensive film and chemistry to produce a radiograph; CR uses a reusable Imaging Plate. The Imaging Plates (IP) contains a layer of phosphors. When the phosphor layer is exposed to x-Rays or gamma rays, a latent image is temporarily stored in the IP. After exposure, the plate is transported to the CR system’s scanner.  Inside the scanner a focused laser beam triggers the release of the stored image as visible light. That visible light is then detected by the PMT (Photo Multiplier Tube) where it is converted into an electronic signal. This analog electronic signal is then sent to the ADC (Analog to Digital Converter) where it is assigned a specific pixel value based on the bit depth of the system. From the ADC, the raw image is sent to the computer/software to be displayed and evaluated by an inspector on a high resolution LCD screen.  The IP is then erased by a specific wavelength of light to purge all residual data from the Imaging Plate. Unlike film, the Imaging Plate is a reusable media. Although the IP does not last indefinitely, if handled with care, they will last an extended period of time. This process decreases the materials used, specifically, the amount of film and processing chemistry.

The Equipment

We have introduced Computed Radiography in our Manchester, CT and Hampton, VA facilities for the inspection of weldments and castings for our Aerospace customers. Both of the labs have installed Fuji Dynamix HR-2 CR systems. Specifically, this system provides both locations with the flexibility to meet industry requirements and demands. The Fuji Dynamix HR-2 system conforms to the requirements of ASTM E 2446 as IP/Special and EN14781-1, and ISO 16371 as IP 1/40. This system also provides the ability to select from 200µm, 100µm, 50µm, and even 25µm scan settings depending on the resolution required to detect various defect sizes. When using a (UR-1) Ultra High Resolution Imaging Plates with a 25µm scan has proven to have a (SRb) Basic Spatial Resolution of 40µm. This means the system is capable of detecting discontinuities less than .002” at 1X geometric magnification when needed.

Some of the Benefits of CR are listed below:

·         Less environmental and safety concerns than film.

·         Reduction in cost when compared to film.

·         Image acquisition is faster than film, increasing production time.

·         More consistent image quality. Film processor chemistry can fluctuate daily. CR scanner is more consistent and repeatable than film.

·         Defect measurements, and annotations can be saved on the image for customer review.

·         Annotations on the images are much easier to read for future review of the images.

·         Images can be sent to customer on a USB memory stick. Saves on shipping costs.

·         Imaging Plates can be custom cut to fit complex geometries.

·         Fuji HR 2 is capable of scanning imaging plates at 25 microns allowing for resolution that rivals film.

·         High spatial and density resolution and Excellent signal to noise ratio (SNR).

·         Images can be shared with the customer engineering or R&D departments for problem solving/troubleshooting. Much more latitude than film. The need for multi load film is virtually eliminated.

·         Film is considered to be equivalent to 8 bit with 256 shades of gray, Fuji HR 2 at 14 bit with 16,384 shades of gray. (Much more latitude and dynamic range than film).

With the addition of CR in our Hampton, VA and Manchester, CT locations, we can offer the CR process to companies interested in utilizing this technology for their aerospace components. In the field, we offer CR for the inspection of piping and other objects. Take advantage of this high quality, cost efficient solution.