Magnetic particle flaw detector is a non-destructive testing equipment used to detect surface and near surface defects of ferromagnetic materials. It detects surface or near surface defects by magnetizing the object being measured and applying magnetic powder to its surface, using the leakage magnetic field generated by the defect to adsorb the magnetic powder and form visible traces.
The basic principle of magnetic particle flaw detector is to utilize the interaction between the leakage magnetic field at the defect of the workpiece and the magnetic powder. When the surface and near surface of ferromagnetic workpieces are magnetized, the discontinuity of magnetic field lines at the defect site generates a leakage magnetic field on the surface of the workpiece, which attracts magnetic particles to form a magnetic particle accumulation at the defect site - magnetic traces, thereby displaying the position, shape, and size of the discontinuity.
Magnetic particle flaw detector is suitable for detecting various ferromagnetic materials, such as steel and iron. It can detect small cracks and defects, such as fatigue cracks and grinding cracks.
The basic principle of magnetic particle inspection is to utilize the characteristics of magnetic materials. When the object being tested is magnetized, the magnetic changes at the defect site will form a leakage magnetic field, and the accumulation of magnetic powder will indicate the defect. The specific methods include:
Wet method: Magnetic powder suspension is used in oil, water, or other liquid media, suitable for detecting small surface defects such as fatigue cracks, grinding cracks, etc.
Dry method: Dry magnetic powder is used in certain special occasions, suitable for local area inspection of large castings, forgings, and large structural components.
classification
According to the magnetization method, it can be divided into electromagnetic yoke flaw detector and rotating magnetic field flaw detector.
According to the current type, magnetic particle flaw detectors can be divided into AC, DC, AC/DC dual-use types, etc. The DC power supply is a rechargeable battery, suitable for field operations without power supply and on-site operations in containers, bridges, pipelines, etc. where high voltage cannot enter. It can work continuously for more than 6 hours on a single charge.
According to the testing method, it can be divided into dry powder method and wet powder method.
According to the magnetization direction, it can be divided into circumferential magnetization method, longitudinal magnetization method, composite magnetization method, and rotational magnetization method.