Liquid penetrant testing - The perfect non-destructive testing solution

Liquid Penetrant Testing (LPI), also known as Fluorescent Penetrant Inspection (FPI), is a widely utilized non-destructive testing technique in the aerospace and medical industries. This cost-effective method is used to detect surface-breaking flaws, such as cracks, porosity, laps, seams, and other surface discontinuities.

Liquid penetrant testing is the perfect non-destructive testing solution.

Image Credit: Kemet International Ltd

Kemet, a leader in precision surface finishing, now offers advanced FPI systems with process control features for repeatability, safety, and traceability of each batch within set parameters.

These systems conform to the ASTM E1417 FPI standard, which is common in both the aerospace and medical industries. Kemet's offerings include standard systems as well as the flexibility to combine automated and manual operations.

This approach results in streamlined and maintainable NDT inspection, with options for integrated wastewater handling and extraction systems that can lead to cost savings in process chemicals, labor, and energy consumption.

The process of Fluorescent Penetrant Inspection

Before conducting a Fluorescent Penetrant Inspection (FPI), it is crucial to ensure that the surface of the material being tested is free from any contaminants that may fill in defects or create false indications of flaws. One effective method for achieving this is through ultrasonic cleaning.

This cleaning process is critical because if the surface of the part is not properly prepared to receive the penetrant, the defective product may be moved on for further processing.

Once the surface has been cleaned, the fluorescent penetrant is applied and allowed to seep into any defects or flaws in the material, a process known as the dwell time. The duration of dwell time varies depending on the material being inspected and the size of the indications being sought.

After the designated dwell time has elapsed, the penetrant on the surface of the material is carefully removed, ensuring that it is only removed from the surface and not from within any identified defects.

Following the removal of excess penetrant, a contrasting developer may be applied to the surface as a background to enhance the detection of flaws.

In the case of Fluorescent Penetrant Inspection (FPI), the inspector utilizes ultraviolet radiation at an appropriate intensity for the intended inspection operation. This process must be conducted in a dark room to enhance the contrast between the glow emitted by the penetrant in the defective areas and the unlit surface of the material.

Once the inspection is completed, the product is returned for final cleaning.

Kemet, a supplier of advanced FPI systems, offers fully automated systems for airframe components, turbine blades, and medical implants, as well as smaller manual systems for less critical parts.

An intelligent combination of automation and manual handling provides labor savings, while an adjustable layout can provide a small footprint. As with the cleaning machines, these FPI systems are durable, safe, ergonomic and user-friendly.

A variety of systems are available, from flexible manual roll track spray lines, with a small footprint to fully automated roll conveyor immersion lines for high capacity, mass production with dipping penetrant application, “Dust Storm” developer chamber and integrated pre and post-wash. 

Additional options include material handling and batch traceability via a data log, fully automated penetrant and developer spray, basket rotation, basket trolleys, and automatic loading/unloading conveyors.

In addition to Fluorescent Penetrant Inspection (FPI) systems, Kemet also offers a range of other cleaning and inspection solutions, such as:

  • Ultrasonic Cleaning Tanks, which come in sizes ranging from 40 to 160 liters, and have over 400 high-performance formulations to choose from.
  • Aqueous Cleaning Fluids that comply with validation standards of ISO 19227-2018 and biocompatibility standards of ISO 10993-18, making them ideal for the medical industry.
  • Passivation lines that comply with the clean room standards of ISO 7.
  • Vacuum Solvent Cleaners with minimal solvent loss that significantly reduce process costs. 

About Kemet International Ltd

Established in 1938, Kemet International Limited is at the forefront of precision lapping and polishing technology, using Diamond Compound and Diamond Slurry, which are manufactured in house to ISO 9001:2015 quality standards. We offer innovative solutions to operations which demand precision finish and close tolerance. Kemet's highly specialised and accurate lapping machines can machine a wide variety of materials for numerous applications.

Operating at the forefront of orthopaedic implant polishing technology for over 20 years, Kemet International Ltd has transformed the quality and cost of manufacture of tibial trays and hip heads/cups.

Kemet's process Laboratories are fully equipped with the latest range of Lapping Machines, Polishing Machines, Ultrasonic Cleaners, Mould Polishing and Metallographic & Geological thin sectioning Equipment to carry out tests on customers' samples. In addition, our team of industrial chemists are able to manufacture bespoke diamond lapping and diamond polishing compounds and diamond suspensions.

Let Kemet help you develop a new process, reduce costs or solve immediate technical problems. Kemet offer training courses covering all aspects of lapping and polishing in our Lapping Laboratories or at your own premises. Kemet International actively takes part in the leading Trade Shows and Exhibitions and have received many awards for our achievements internationally.

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Last updated: Jan 24, 2023 at 5:51 AM


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