At DCL Engineering Group, we employ several methods of non-destructive testing of components. Gear housings are usually checked where required using a dye penetrant method of crack detection. Gears, keys and shafts undergo the more sophisticated method of Fluorescent Magnetic Particle checking, where a specially designed magnetic tool induces a magnetic field in the components. Fine metal particles are sprayed on, and the specific high powered fluorescent lamp will show any imperfections on the surface of the component being checked. For more detailed analysis, full x-rays can be done if required.

The benefit to you, as a customer, of this specialised checking procedure is that DCL Group has removed the possibility of inherent failure occurring if cracking was present and not detected. It is another example of the way that DCL Engineering Group goes that extra distance to give you the greatest chance of a long service life in your component once refurbished by us.

Fluorescent Magnestic Particle Testing

Magnetic particle testing is effective in finding surface deterioration on ferromagnetic (materials that can be magnetised) materials. Once the item is temporarily magnetised, fine iron particles are applied to the surface and will form along the lines of the magnetic force from the magnet. Flaws on the surface will cause the lines to be distorted and this method is best suited for detecting surface flaws.

Dye Penetrate Inspection

Dye Penetrate Inspection (DPI), also known as liquid penetrant inspection, is a common and low-cost method to detect surface cracks on non-porus materials (not having vessels that appear as pores). DPI can also be used on non-ferrous materials and is used to detect cracks, leaks, casting and forging defects. Liquid penetrant is applied to the surface and absorbed into defects by capillary action. After a period of time the penetrant is drawn out and a visual inspection is performed on defects.

DPI is used when Fluorescent Magnetic Particle Testing is impractical due to the size or shape of a component is by using a dye to see if it soaks into a surface crack. This is most often used on larger fabrications or castings, such as gearbox housings and large flanged couplings.


If a component is suspected of internal faults which don’t show on the surface, such as some forgings, then the component can be x-rayed to determine the internal structural soundness prior to proceeding with the component.

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