Dye Penetrant and Fluorescent Powder Testing
When your quality standard requires a surface finish free from tiny cracks, pores or other surface glitches that are hard to detect by the human eye, dye penetrant testing is used for both ferrous and nonferrous materials. The part is cleaned and a colored dye solution is applied to the surface of the part. The dye is suspended in penetrating oil and will freely flow into these surface imperfections. When our special developer is applied, the defects are clearly indicated.
A similar method suspends fluorescent powder in penetrating oil. This brightly colored film covers the parts and the penetrant finds its way into any defects.
Then the casting is dusted with drying powder and the fluorescent solution is drawn from the defect. Then a visual inspection in an ultraviolet light environment will easily show the defects as they will glow.
Generally, dye-penetrant testing techniques will identify defects on the surface of the casting and will not detect internal porosity or shrinkage that is not open to the surface. But these methods can detect rounded indications for porosity or gas on the casting surface. These two methods are less expensive than radiographic testing.
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Below are the main steps of Liquid Penetrant Inspection:
The test surface is cleaned to remove any dirt, paint, oil, grease or any loose scale that could either keep penetrant out of a defect, or cause irrelevant or false indications. Cleaning methods may include solvents, alkaline cleaning steps, vapor degreasing, or media blasting.
2. Application of Penetrant:
The penetrant is then applied to the surface of the item being tested. The penetrant is allowed to soak into any flaws. As expected, smaller flaws require a longer penetration time.
3. Excess Penetrant Removal:
The excess penetrant is then removed from the surface. The removal method is controlled by the type of penetrant used. Water-washable, solvent-removable or hydrophilic post-emulsifiable are the common choices. Emulsifiers represent the highest sensitivity level, and chemically interact with the oily penetrant to make it removable with a water spray.
The inspector will use visible light with adequate intensity (100 foot-candles or 1100 lux is typical) for visible dye penetrant. Ultraviolet (UV-A) radiation of adequate intensity (1,000 micro-watts per centimeter squared is common), along with low ambient light levels for fluorescent penetrant examinations. Inspection of the test surface should take place after 10- to 30-minute development time, depends of product kind. This time delay allows the blotting action to occur. The inspector may observe the sample for indication formation when using visible dye. It is also good practice to observe indications as they form because the characteristics of the bleed out are a significant part of interpretation characterization of flaws.
5. Post Cleaning:
The test surface is often cleaned after inspection and recording of defects, especially if post-inspection coating processes are scheduled.
How we prove your products meet standards?
We start by understanding your quality standards. We comply with ASTM standards and we are NADCAP accredited for Flourescent Penetrant, Magnetic Particle and Radiography Film. The standards that your parts need to meet will determine the process that we use. Below are the processess that we specialize in perfoming.