Non Destructive Testing (NDT) in Modern Manufacturing

Do you really want to just “hope that it’s right”?!?!

 

Over the past 30 years or so manufacturing processes and techniques here in the US and abroad have improved significantly, giving us a higher level of quality and consistency in the products that we build, as well as keeping manufacturing costs (and in turn, retail prices) down. One of the key items that has evolved significantly in the last 3 decades is the use of non-destructive testing (NDT) integrated directly into the manufacturing process. NDT is not really a specific type of testing per se, but more of a mentality. The philosophy is that you are able to inspect for critical defects in components or workmanship, often in areas that cannot be seen by an unaided human eye, and during the inspection you do not damage or destroy the part in any way. Some of the more common techniques of NDT are Real-Time Radiography (X-ray), ultrasonic testing, eddy current technology, magnetic particle testing, and liquid dye penetrate testing. While each of these various methods are very different in their core technologies and application, the end goal of each is the same: Verify and validate component quality in areas that are difficult or impossible to see otherwise without damaging or destroying the part in the process.

Industrial radiography started to show up in mainstream manufacturing shortly after the end of WW2, and we’ve been finding new uses for it ever since. A very good example (and one of the more mature applications) of this is the use of radiography in welding inspection. It’s very easy for a welder to lay a very pretty cover pass over inferior root and/or filler passes. With just a visual inspection, the weld in question would probably pass with flying colors. But once you shoot an x-ray of the weld, all the ugly stuff inside is on display for the whole world to see. Critical welds in building, bridge, and pipeline construction have long been inspected in this manner to confirm that the finished weld is a solid structural union of the parent metals.

While NDT solutions have long been a key part of manufacturing, it wasn’t always real-time feedback as it now can be, and it wasn’t always integrated directly into the manufacturing process. ‘Spot check’ NDT procedures were once the norm (and can still be found in many manufacturing processes today), where a small percentage of parts were randomly NDT inspected after completing the entire manufacturing cycle. If all of the parts pass the spot check with flying colors, life goes on as usual. If failures showed up during NDT analysis, then things get complicated. Huge lots of parts need to be quickly quarantined and 100-percent NDT inspections on the quarantined lots will usually follow. Needless to say, NDT spot checking any of your mission-critical components post-manufacture is a sketchy thing at best and a costly nightmare at worst.

Using a lean automation mindset, integrating “100 percent” NDT inspections into critical processes allows validation of component quality prior to adding any additional value to the part. Rejected parts are offloaded at the point of failure instead of later down the line, with no additional work being performed on the flawed part (and consequently no additional costs absorbed). This also minimizes or completely eliminates the need for component backtracking or quarantines of part lots that would normally occur if a problem wasn’t caught and dealt with at the point of failure.

Critical components such as automotive safety components, implanted medical devices, and many other complex manufactured items have long relied on integrated NDT solutions to assure reliable, life-saving performances over and over again. If your mission-critical manufacturing process truly is a matter of life and death, it’s very probable that an integrated NDT solution in your manufacturing process may be a wise investment for your company.

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