According to the appearance of the sample and the detection target is not the same, can choose different ways of the coil, generally through the type, probe type and insert type coil 3. Through the coil is used to detect pipe fittings, rods and cables, its inner diameter is slightly larger than the objects to be detected, the application of the objects to be detected in the coil at a certain rate, can detect cracks, impurities, dents and other shortcomings. Probe coil is suitable for partial detection of samples. When the coil is used, it is placed on the metal sheet, pipe or other parts to check the eddy current loss, fatigue and cracks on the inner cylinder of the take-off and landing support rod and the turbine leaf. Insert coil, also known as the internal probe, is placed in the hole of the pipe or parts for the cavity online detection, can be used to check the etching level of the cavity of a variety of pipelines. In order to improve detection sensitivity, probe and plug-in coils are mostly equipped with transformer skeletons. Eddy current method is the key to the production line of metal hose, rod, wire rapid detection and its large number of parts such as bearing steel balls, valve of eddy current flaw detection (at that time in addition to the eddy current equipment configuration is needed of the fully automatic handling and transport machinery equipment), material screening and intensity is measured, can also be used to measure the coating and coating of fine really thick.