Computed tomography (CT) is a process wherein numerous x-ray images are acquired as a test object is rotated around. Each individual radiograph provides a two-dimensional view through the object, and then all of these images are reconstructed using sophisticated computer techniques. The result is a 3D-like representation of the part, similar to a CAD object. It can be moved in virtual space, and planes cut through the past, showing internal features.
Liquid penetrant testing exploits the high capillary action of particular fluids to seep into surface breaking features, thus revealing the presence of flaws. In this video, a basic red penetrant is applied to a part and, after a specific procedure, is blotted back out of a crack, spreading laterally enough to provide an indication vivid enough for detection. While ostensibly simple in application, this test method requires careful attention to processing details to maximize its potential for flaw-finding.
This video shows the magnetic particle process. When a current is passed through a test object, a magnetic field is established perpendicular to the current direction. At the point of surface breaking cracks, this field leaks into air, attracting fine magnetic particles. In the instance shown, the particles have been tagged with a fluorescent tracer to vividly stand out when viewed under ultraviolet lighting.