Magnetic Particle Testing

               The magnetic particle testing method (MT) is one of the most sensitive, reliable and productive NDT-methods for surface testing of products from ferromagnetic materials. The method is based on the attraction of ferromagnetic particles by force of leakage flux which appears above surface defects like cracks, laps, lacks of fusion, and pores after an adequate magnetisation. MT can be used for indication of open surface defects and under certain conditions for detection of near-surface defects. A higher probability of detection is achievable if the direction of a defect is oriented perpendicularly to the direction of the applied magnetic field. The smaller is the angle between the defect and magnetic field lines, the weaker will be the indication.

Microscope image of cracks	Fluorescent MT image of the cracks
APPLICATION FIELDS: Metallurgy Engineering  Aircraft Industry Automotive Industry Ship Building Constructional Engineering Pipelining Power Machine Building Chemical ENgineering Transport (air, rail, motor transport).	DEFECTS INDICATION Cracks Hair Cracks Tears Silver Spots Lacks of Fusion Pores

The magnetic particle testing is a procedure which consists of following steps:
                1. Preparation of the test objects’ surfaces for testing;
                2. Magnetisation of the object;
                3. Application of magnetic particle suspension (powder) onto the test object;
                4. Inspection;
                5. Demagnetisation.

Circular, longitudinal or combined magnetisation is used for the magnetic particle testing. There are a lot of magnetisation schemes, some of which are shown below.