X-ray inspection can be found lost wax casting casting internal defects, such as porosity, shrinkage cavity and crack, inclusion, etc.On important castings, such as defense industry with type I castings, typically after 100% of ray inspection.Commonly used ray are: X rays, and g rays.Penetration of the former than the latter, but the sensitivity is higher than the latter, these rays can penetrate the metal, make the photographic film.Ray through the objects, and objects in the atomic interaction, ray energy was constantly absorbing and scattering and attenuation.The faster, the density of the object, the greater the energy attenuation of castings in the hole, the density is far lower than the density of the metal, such as the inclusion ray with these defects, the attenuation is small, on the negative energy is larger than zero defect parts, therefore, can show the shape of the defect on the film.