Online and Real-Time Measurement of Magnetic Powder Dosage in Magnetic Particles Inspection (MPI) of Materials

The feasibility of a method to provide assurance of the compliance of inspections of component quality to

international standards will be assessed. The method applies to magnetic particle inspections which detect

cracks in metallic components and involves the use of a high frequency electromagnetic sensor. The sensor

resonates at a frequency in the microwave frequency band. The working fluid used in the inspection is a dilute

suspension of ferromagnetic particles, in which each particle is coated with a fluorescent dye. Particles will

collect in the magnetic fields around cracks in the component being inspected and can be found via their

fluorescence. The sensor will measure the concentration of particles in the fluid during the inspection, a sample

of the fluid being drawn from the testing apparatus and pumped through the sensor before being returned to

the testing apparatus. The current method of measuring particle concentration is performed prior to

inspections and takes several hours, the new method is a real-time solution which is also more appropriate to

automatic data logging.