One of the methods of non-destructive tests is to find defects that reach the surface in non-porous materials.

Defect signs can be seen regardless of the size, configuration, internal structure or chemical composition of the workpiece being tested and regardless of the direction of the defect. Penetrating liquid can penetrate (and be drawn) inside different types of pores that lead to the surface by using capillarity. For this reason, this method is suitable for detecting all surface cracks, lamination, shrinkage defects, porosity and similar defects in cast parts, forging, welding and other production methods.

applications:

Liquid penetrant testing is widely used to test ferrous and non-ferrous metal castings, powder metallurgy parts, and ceramics and glassware.

In practice, the penetrant inspection process is relatively simple. The equipment is generally simpler and less expensive than most other NDT methods. When used on ferromagnetic metals, in some cases, the sensitivity of the liquid penetrant test is better than that of the magnetic particle test.

Limitations:

The biggest limitation of liquid penetrant testing is the ability to detect defects that only reach the surface. Another factor that may reduce the effectiveness of penetrant testing is the surface roughness of the part being tested. Hard, uneven and porous surfaces increase the possibility of error.

The penetrative liquid test mainly depends on the wettability of the workpiece surface so that the liquid penetrates into the holes. Cracking ability is affected by capillary action.

The penetrative liquid test requires at least the following 5 items:

Surface preparation
Penetrating liquid
Wipe off excess penetrant
Application developer
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