Page 251 - CITS - Welder - Trade Theory

WELDER - CITS

Eddy current testing, Principal, advantage

Objectives : At the end of this lesson you shall be able to
• state eddy current
• explain the applications of the eddy current
• explain the advanctages of the eddy current.

Eddy Current Testing is a versatile non-destructive testing method that is typically used to identify defects in
materials without causing any harm to the object or reducing the shelf life of the component.
It permits examining the conductivity, thus the hardness, geometry, and chemistry of any material that is electrically
conductive when it is brought into the vicinity of a coil.
Generally, Applications of Eddy Current Testing are used to detect porosity, voids, cracks, hardness, the density
of the material, thickness, thread, and surface condition.
Applications of Eddy Current Testing
Eddy Current Testing includes various applications; here are some of the applications that are widely used.
1 Material Sorting

Electromagnetic sorting bridges and Ferrous segregation are some of the valuable tools for sorting steel that
has been hardened.
Conductivity meters can be used in sorting copper and aluminum alloys in both cases, i.e., hardness variation and
compositional variation.
A lot of concentration is required in order to ensure that the variation being inspected is the appropriate one.
For instance, the occurrence of a change in the conductivity of an aluminum alloy is due to a change in its
composition or a change in its hardness.
This particular method delivers a better classification of the properties that material holds than any other method
used for sorting materials because eddy current fields permeate below the surface of the components.

2 Weld Testing
Eddy current testers with high frequencies have been used for a long time to identify cracks in ferrous welds.
There is an advantage to executing this method, as it is capable of detecting cracks through paint layers.
One drawback of this method is the high noise levels that result from the permeability changes that occur in the
weld. This is one of the major applications of ECT.
3 Crack Detection
Eddy Current Testing equipment for identifying cracks can be classified into two categories.

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CITS : C G & M - Welder - Lesson 83 - 97