NDT provides an excellent balance between quality control and cost-effectiveness. An x-ray machine or radioactive isotope is used as a source of radiation.
Radiation is directed thought a part an onto film.
When the film is developed, a shadowgraph is obtained that shows the internal soundness of a part. Possible imperfections show up as density changed in the film, in much the same manner as an x-ray can show broken bones. Surface imperfections will distort the magnetic field and concentrate the iron particles near imperfections, thus indication their presence. The test object or material is coated with a visible or fluorescent dye solution. The excess dye is removed from the surface, and then a developer is applied.