Non-Destructive Test/NDT/NDI

This is a technique to find small discrepancies or cracks in materials or parts, without causing damage the material or part.

The effect of discrepancies or cracks may cause the integrity of a material or part to deteriorate, and benefits reliability checks, evaluations and trouble shooting.

The most commonly used methods are:

- Visual inspection

- Penetrant dye

- Magnetic particle

- Ultra sonic

- X-Ray

- Eddy current

- Thermography

- Shearography

Penetrant dye

This is a method used to detect surface breaking defects. It is used on non-porous materials and therefore used specifically on non-ferrous materials as well as ferrous metals.

The principle of the method lies in a penetrating fluid, hygroscopic properties and visual inspection.

Magnetic particle

This is a method which can be applied to ferrous metals only and is able to produce evidence of discrepancies on or just below the subject surface.

The principle of the method lies in the ability to produce a magnetic field in the part or material and use a responsive medium to detect a so called "leak field" where a discrepancy is located.

Test conditions

Penetrant dye and magnetic particle testing can be performed in preferably well lit areas, however it is preferred to perform the test in a darkened inspection room equipped with an UV inspection lamp as well as a UV background lamp. This addition to the inspection/test improves the quality (visibility) of the process by approx. 10 times due to the responsiveness of the human eye to UV illumination in a dark setting.