Process Control of Temperature
The temperature of the penetrant materials and the part being inspected can have an effect on the results. Temperatures from 27 to 49oC (80 to 120oF) are reported in the…
Use and Selection of a Developer
The use of developer is almost always recommended. One study reported that the output from a fluorescent penetrant could be multiplied by up to seven times when a suitable powder…
Penetrant Removal Process
The penetrant removal procedure must effectively remove the penetrant from the surface of the part without removing an appreciable amount of entrapped penetrant from the defect. If the removal process…
Penetrant Application and Dwell Time
The penetrant material can be applied in a number of different ways, including spraying, brushing, or immersing the parts in a penetrant bath. The method of penetrant application has little…
Selection of a Penetrant Technique
The selection of a liquid penetrant system is not a straightforward task. There are a variety of penetrant systems and developer types that are available for use, and one set…
Preparation of Part
One of the most critical steps in the penetrant inspection process is preparing the part for inspection. All coatings, such as paints, varnishes, plating, and heavy oxides must be removed…
Developers
The role of the developer is to pull the trapped penetrant material out of defects and spread it out on the surface of the part so it can be seen…
Emulsifiers
When removal of the penetrant from a defect due to over-washing of the part is a concern, a post-emulsifiable penetrant system can be used. Post-emulsifiable penetrants require a separate emulsifier…
Removability
Removing the penetrant from the surface of the sample, without removing it from the flaw, is one of the most critical operations of the penetrant inspection process. The penetrant must…
Dimensional Threshold of Fluorescence
The dimensional threshold of fluorescence is a property that is not currently controlled by the specifications but appears to largely determine the sensitivity of a fluorescent penetrant. A. L. Walters…
