Eddy current testingET

This method is widely used to detect surface defects, to sort materials, to measure thin walls from one surface only, to measure thin coatings and in some applications to measure case hardening depth. This method is applicable to electrically conductive materials only. In the method, eddy currents are induced in the object by bringing it close to an alternating current carrying coil. The alternating magnetic field of the coil is modified by the magnetic fields of the eddy currents. This modification, which depends on the condition of the object near to the coil, is then shown as a meter reading or cathode ray oscilloscope presentation.