Dye Penetrant Testing
We provide single and serial testing of your components for surface defects with dye penetrant testing
Non destructive testing with dye penetrant testing (PT)
What is dye penetrant testing?
Dye penetrant testing (PT), also called red-white testing, is a surface crack detection method. It is suitable for testing surfaces for defects in almost all materials and is widely used in industry.
How does dye penetrant testing work?
Surface inspection by means of dye penetrant testing makes use of the capillary effect. The capillary effect describes the behavior of liquids in contact with capillaries, e.g. in contact with tubes, cracks, cavities, notches and scratches. Due to an interaction of the surface tension of liquids and materials, a liquid is also drawn into such capillaries by gravity. An everyday example of the capillary effect would be, for example, the absorption of water by a sponge or the rising of water in a straw.
The first step is to carefully clean and degrease the surface of the component to be tested so that the flaws are open to the surface without interruption.
Spray on dye penetrant:
Then spray the surface with the intensely red colored or fluorescent dye penetrant. Due to the capillary effect, the dye penetrates into the defective areas of the component.
Removing the dye penetrant
After a certain exposure time, the dye penetrant is carefully removed from the surface, for example with water or a system cleaner, and the component is dried.
Spray on developer
In the next step, a white developer is sprayed on. The red penetrant “bleeds” from the defects, making them visible. If fluorescent dye penetrant is used, defects are made visible by irradiation with UV light.
When is dye penetrant testing used?
Dye penetrant inspection is used to detect defects on the surface of the material.
Detectable defects are:
- Surface shrinkage cavities
- The defect must be open to the surface
- The material to be tested should not be porous
- The surface of the material must be clean and free of grease
- Smallest detectable flaw:
From 0.01 mm
Detectable defect location:
* The specifications depend on the geometry and physical properties of the material to be tested and are therefore only intended as a guideline.
Dye penetrant testing with VOGT Ultrasonics
We test your components either single or in series in our VOGT test center in Burgwedel (Hanover) or directly at your site.
Non destructive testing by dye penetrant testing (PT) of component fixtures of a machine
PT Testing the front suspension of a passenger aircraft
PT on the wind vane of a large wind tunnel. There are bleeding indications of surface porosity, but no stress cracks.