Magnetic particle inspection is the defect of detecting the surface and near surface of workpiece. Including crack!
Detection of cracks in general with surface detection (magnetic particle or permeability), high sensitivity. In view of the hook surface oil is more, the effect of penetration test is not good, and the hook is generally ferromagnetic material, so the effect of magnetic particle inspection is good.
The cracks of crane hook are divided into manufacturing cracks and fatigue cracks. Personal understanding should be fatigue crack.The fatigue crack of the hook usually appears in 2 places:1, the hook of the inner concave plastic deformation or wear place, from the plastic folding initiation;2. The thread position of the straight handle hook;If it is sling, it will be more complicated.Fatigue crack detection generally use magnetic powder or penetration (magnetic powder first), but for the threaded parts may be missing, the need to increase ultrasonic testing;Flaw detection is a relatively strong professional work, the hook is part of the special equipment, the state provides for an annual inspection and testing should be open, non professional staff is not recommended for testing.
