Table of Content
- Applications of Eddy Current Testing
- Purpose of Eddy Current Testing
- Advantages of Eddy Current Testing
- Limitations of Eddy Current Testing
- Key Takeaways
In the world of non-destructive testing, eddy current inspection stands out as a versatile and powerful technique used to inspect a wide range of conductive materials. 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.
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Applications of Eddy Current Testing
Eddy Current Testing (Eddy Current NDT) 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 aluminium 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. The first one is a high-frequency instrument for detecting surface-breaking cracks in non-ferrous and ferrous components. The second one is a low-frequency instrument for inspecting subsurface cracks in non-ferrous components.
In ferrous materials, identifying the subsurface cracks is possible only when the materials are saturated magnetically to eliminate permeability impacts. This is a complicated procedure that is achievable with automated tube testing systems. Applications of Eddy Current Testing are widely used in detection.
In the Detection Procedure of Surface Cracks, eddy currents are too sensitive. High frequencies of the order of 2 MHz provide high resolution, but the probes are too small, and covering a vast surface area consumes a lot of time. Large probes are required for low-frequency crack detectors to enable favorable coil inductances.
The setting of the frequency is critical, and it is in the range of 10 Hz to 100 Hz, which depends on the depth of penetration needed. Phase sensing circuits are necessary because phase changes, rather than amplitude changes, have a significant impact on the subsurface eddy current fields.