performing liquid penetrant dye inspection

V

Vulcanite

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Jan 16, 2009
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Do you have to have alot of expensive equipment to perform liquid penetrant dye inspection to look for flaws in steel w/ the dye & the black light?

I heard of it but don't know what exactly is involved? Wondering if this is cottage industry friendly?
 
There are two types of dye penetrant tests .One is done with black light ,the other is done in daylight.The second one is done with a red dye which is put on the metal ,the metal wiped off and a white 'paint' is sprayed on. If there are cracks the dye has gone into the crack and then bleeds into the white paint.This is specifically for cracks and is a common proceedure for welders. The one with black light uses an electrically charged piece of steel and can detect cracks and some other near surface defects.
 
As mete said, 2 types of pen test. It'll be cheapest for you to go with the visible method, as you don't need a black light. Capillary action is the vehicle which makes this test work, so the defects must be open to the surface. After the part being tested is cleaned of dirt, grease, etc. using a solvent, the dye is applied for a set time. Then wiped clean with a dry rag to remove excess penetrant, then once more with a rag dampened with solvent. After the solvent evaporates the developer (which I liken to baby powder) is applied. If their are any defects the developer draws the dye out of them. As the penetrant is typically red, it shows up very well against the white background of the developer.

Some mag particle methods will find near surface discontinuaties. Mostly all ferrous materials are tested using Mag Particle.
 
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Finally, a question about something I've done. The start up for dye penetrant is just buying the dyes, solvent, and developer. I dont know if its necessary, but suppliers sell all three, so it seems reasonable to use the solvent, developer, and dye all from the same source. Search the web for basic technique and supplies, though T Blades technique is good. The dwell time can vary a little, and the time allowed for the developer to do its work can too. Magnaflux supplies some of the stuff we use at work for magnetic particle and penetrant testing. Penetrant is only for surface flaws. You can get flourescent dyes for penetrant testing, but without a black light they arent worth much. If you have a black light, you can see cracks from across the room, if its dark. Its pretty cheap, compared to other testing methods, to get started and works well if you have some experience. I think Bob Engnath used this method to test his japanese style blades. His old website says he used a crack detector spray. I assume it was penetrant testing. For an information overload, check out the American Society of Non-destructive Testing (ASNT). This seems a good way to test blades for macroscopic cracks.
 
Most welding supply stores carry some sort of dye penetrant kits. Maine Oxy carries the Visible Magnaflux. You can pick up fine cracks that could be missed otherwise with the visible dye.

Here is a good place to start: www.ndtmart.com

If you go with fluorescent dyes then you will need a black light or a blue light with the orange lens. The cost goes up just getting the black light.
 
"M" Post reported. - Now Deleted
Not cool, joining forum to post on 11 year old thread to promote your company. It isn't even as if the Original Poster is still interested, not been on forum since December 2012.
 
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