Magnetic particle testing

The principle of magnetic particle inspection is to magnetize the workpiece made of magnetic conducting metal materials to the saturation degree. If the material is very uniform inside and there is no defect, there will be evenly distributed magnetic field lines inside. If there are cracks, slag inclusions or air holes and other defects on the surface or near surface area of the workpiece, these defects will hinder the passage of magnetic field lines, generate magnetic flux leakage phenomenon, and make the surface on both sides of the defect produce magnetic field lines A pair of N, S pole local magnetic field is generated. At this time, if the magnetic powder or magnetic powder suspension is placed on the surface of the inspected workpiece, the magnetic powder will be absorbed by the leakage magnetic field, resulting in the agglomeration of magnetic powder, thus clearly showing the image of the defect.            Magnetic particle testing is suitable for the detection of raw materials, semi-finished products, finished products and parts in service, as well as the detection of plates, profiles, pipes, bars, weldments, steel castings and forged steel parts. It can find the surface and near surface defects of the workpiece. It can't check the non-magnetic materials, such as austenitic stainless steel, copper, aluminum, etc. magnetic particle testing is widely used in the inspection of metal materials and finished products because of its intuitive defect display, low cost, fast inspection speed and high inspection accuracy