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Radiographic inspection is a nondestructive testing technique used to evaluate objects and components for signs of flaws which could interfere with their function. It is accomplished with the use of radiographs, images generated by bombarding the object under inspection with radiation. X-ray and gamma ray radiographic inspection are the two most common forms of this inspection technique. Materials testing companies often offer radiographic inspection to their clients, and some companies have their own inspection facilities for in-house inspections.
In film radiographic inspection, the object is mounted in a manipulator with sensitized plates behind it. X-ray or gamma ray radiation is aimed at the object, and the plate is exposed by the radiation which passes through the object. Once developed, the plate reveals an image of what is going on inside the object, in very precise detail. This can be used to identify flaws such as cracks, thickness variations, inclusions, bubbles, bad welds, and so forth.
The disadvantage to using film is that it takes time. Sometimes, companies prefer to use real time inspection, in which the radiographic image is displayed on a monitor as a device is moved over the object being inspected. This method tends to have less clear resolution, and it doesn't create a permanent record like film does unless the real time inspection is recorded, as is done in some cases. The advantage is that it can be done very quickly, which can be key during rapid inspection and repair.
Inspection radiography may be required by law for safety reasons, or a company may opt for using this technique to assure that their products are of high quality. The nondestructive nature is also an advantage, as radiographic inspection can be used to evaluate things quickly without needing to disassemble them or damage them in the process. For example, when airlines inspect aircraft components such as landing gear, radiographic inspection can be used to look inside to confirm that the components are in good working order.
Special precautions need to be followed when performing radiographic inspections, because people can be harmed by the exposure to radiation. People and devices need to be adequately sealed, and the inspection area must be clearly marked with warnings so that people understand that a radiation risk is present. It's also important to follow the protocol established for safety, using the radiographic inspection equipment as directed and with all safety features operational and working.
@Charred - I agree. Of the two processes described in the article, I prefer the film based radiographic process.
I understand the case for the videotaped approach if you need to move stuff quickly down an assembly line, but I prefer the improved clarity of the film image. Also, I believe that film can be scaled and resized at a much higher resolution than a frame from a video tape could.
I think it depends on what you’re trying to do. For missions critical applications like airplanes or defensive weapons systems, I think it’s worth it to take your time and get it all on film.
Industrial radiography seems like the way to go if you want to do non destructive testing of equipment, especially for small metal objects like ball bearings with very low tolerances. I can’t imagine how you would detect a hairline crack on such an object any other way.
I also think that another usefulness of the radiographic image, since it is so complete, is that you could probably use it to create a 3D model. Perhaps you could use these 3D models as baseline templates from which you can create other metallic objects at a miniature scale.
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