Endoscopy as a NDT Tool for Failures Prevention in Machineries

The last 2 decades different high tech optical tools have been developed for allowing different visual examinations through optics of very small sizes permitting them to be entered, f.e., inside lubrication holes of machines and directly inside machine sub-assemblies such as rolling-elements bearings and gear meshes, bringing back through optical fibers the signal and allowing the user to record, store pictures and films of what is under examination. Such modern tools allow then the Failure Analyst to examine each functional or working surfaces searching for potential signs of "nascent" or extended damages (Pitting, wear, overheating, ...) increasing in such a way "safety operations" and avoiding unplanned machineries stops. After a short review of the endoscopy principles, an overview of the different technologies that nowadays exists, a point will be done on the performances, advantage and disadvantages of theses FA&P techniques. Some industrial cases studies devoted to heavy industries (Paper, Mining, Cement) will underline this article.