If you want to learn more about quality control with respect to an organization, chances are good that you’ll run across the subject of nondestructive testing, or NDT. It sounds like NDT is a very complicated process, but that’s not the case at all. In fact, as time passes you’ll find that NDT has a very straightforward side.
Nondestructive testing (referred to later on in this guide as NDT) covers everything from checking out materials and inspecting them, to looking at a part or component for irregularities. The difference that separates this type of testing from other methods is that the part can still be put into production after NDT phases are completed. As you can imagine, this means that NDT protects the company by allowing product to continue to be sold, rather than losses in manufacturing piling up due to the testing process. It’s not always possible to use NDT but it’s a recommended practice when it’s feasible.
Is there a time when you don’t want to use NDT? Absolutely. If you’re handling materials where you need to test tensile strength, or fracture toughness, or even how ductile the material is, then destructive tests are definitely the way to go. NDT covers discontinuities, differences, and irregularities.
Reliability across the board is what you want to find in a product. This is very important as costs go up when you have to refine a product over and over because it’s not safe. In some fields where heavy government regulation is present, NDT helps keep fines from occurring due to noncompliance.
NDT and quality control go hand in hand. A uniform standard of quality is easier to obtain when you have measured testing processes that can yield you a wider variety of data.
There are lots of different test methods that fit under the NDT umbrella. Some companies use laser testing, or ultrasonic testing. Ultrasonic testing is actually very interesting. High pitched frequencies are introduced into the part and some of the sound will return back to the sending unit. As long as the operator knows what speed the sound is moving through the part and the time needed for the sound to come back to the unit, the distance is easily calculated. The sounds used in this type of testing are too high to be heard by the human ear, but they can still affect the particles within a component.
You have two types of motion present within the unit being tested: compressional motion and shear motion. Both directions of motion can highlight inconsistencies in the material, if the sound returned moves at a different rate than the established standard.
One of the most interesting techniques of laser testing is actually holographic testing. In this procedure, a laser is used to look at changes to the surface of a testing component as direct stress is applied. This can be mechanical stressors, extreme pressure, heat, or even excessive vibration. The testing procedures would be documented by the operator at every stage, and the data collected would be used to determine whether or not the material passes the inspection or not. If not, the component is discarded at a lower loss than if it were allowed to move forward in the manufacturing stage.
No matter what method you choose for NDT, you’re bound to gain interesting insights into your quality control process. Check it out today!
