Non-Destructive Testing FAQs

Non-destructive testing (NDT) is a testing method that will not cause damage or alter the integrity of safety-critical components being tested for imperfections.

Non-destructive testing includes Dye Penetrant Inspection, Fluorescent Penetrant Inspection (FPI), Magnetic Particle Inspection (MPI), x-ray, Ultrasonic, and Eddy Current.

Non-destructive testing is important because it provides a consistent and safe method of ensuring the fidelity of safety-critical components. This type of testing prevents the use of worn parts that can break and cause injury.

Fluorescent Penetrant Inspection (FPI) is a testing method used to detect cracks in safety-critical components that are made out of non-porous materials, such as metals, plastics, ceramics, and glass. The process utilizes fluorescent dye, which is applied to the part and fills any existing cracks. A special UV light is then used to illuminate where the penetrant has gotten into the imperfections of a part being tested.

Magnetic particle inspection (MPI) is a non-destructive testing method that is used to detect surface defects and cracks in parts that are made out of magnetic materials, such as iron, nickel, cobalt, and other ferromagnetic alloys. MPI is the process of using a magnetic field to determine where a crack may be on parts such as forgings, castings, fasteners, weldments, machined, or stamped parts.

Dye penetrant inspection, also known as liquid penetrant inspection, is also interchangeable with fluorescent penetrant inspection. It is dependable and harmless to the part being tested. Fluorescent dye is applied to a part, and the cracks hold the penetrant within, making them visible to the naked eye once the developer is applied and a UV light illuminates the dye.

The first step in non-destructive testing is to clean the part. It is important that the correct cleaner is used in the cleaning process before the penetrant can be added to the surface of the part. This ensures that the defects on the part surface are accessible to the penetrant fluids.

A penetrant is a substance that can get into cracks and other surface defects. It is used in dye penetrant inspections to help make cracks and imperfections in parts visible to the naked eye. Fluorescent dyes are also used as penetrants and developers are used to bring them to the surface to help make cracks visible under UV-A light.

A product can be tested up to ten times depending on the specification. Automating a process will increase process precision to reduce process variability, minimizing the number of times a part needs to be processed. This reduction can be significant—sometimes on the order of 1/3!

A developer is a substance that is used to bring the penetrant back to the surface of the part, thus making the penetrant visible as it emerges from a crack or imperfection in a part.