Ect ndt is a non-destructive testing method which uses the principle of electromagnetic induction to evaluate the properties of conductive materials and their workpieces or find defects by detecting the changes of induced eddy current in the workpiece to be tested.
In industrial production, ect ndt is one of the main means to control the quality of various metal materials and a few non-metallic materials (such as graphite, carbon fiber composites, etc.) and their products. Compared with other ndt methods, it is easier for ect ndt to realize automation. It has a very high detection effect especially for profiles such as tube, bar and wire. Its working principles are as follows:
This is how the eddy currents are generated. When a conductor is placed in a variable magnetic field, there is a induced electric field of eddy currents around the changing magnetic field. The induced electric field acts on the free charge in the conductor, which makes the charge move and forms eddy currents.
The alternating current is connected to the detection coil to generate an alternating magnetic field perpendicular to the workpiece. When the testing coil is close to the workpiece to be inspected, eddy current is induced on the surface of the workpiece, and a magnetic field opposite to the original magnetic field is generated at the same time, which partially offsets the original magnetic field, resulting in changes in the resistance and inductance of the detection coil. If there are defects in the metal workpiece, the strength and distribution of eddy current field will be changed, and the coil impedance will be changed. The defect can be judged by detecting this change.
With the development of microelectronics and computer technology and the application of various signal processing technologies, ect ndt transducer, ect ndt signal processing technology and ect ndt instruments have made great progress.