Please enable JavaScript.
Coggle requires JavaScript to display documents.
Chapter 4a - Magnetic Particle Inspection MPI (part 1, 2, 3) - Coggle…
Chapter 4a - Magnetic Particle Inspection MPI (part 1, 2, 3)
MPI
Is a method that can be used to detect surface & near surface defects/flaws/discontinuities in ferromagnetic materials (steel & iron)
Is fast & relatively easy to apply & part on the surface preparation is not as critical as for some of the NDT methods. These characteristics make MPI one of the most widely utilized NDT methods
Is based on the principle: magnetic lines of force (flux) will be distorted by the presence of the defect in a manner that will reveal its presence
-
-
-
Methods used
Inspect variety of product forms including:
- Many different industries used MPI to determine a component's fitness for used
- Some examples of industries that use magnetic particle inspection are the steel (structural), automotive, petrochemical, power generation & aerospace industries
- underwater inspection is another area which MPI is used to test the item such as (offshore, structures & underwater pipelines)
-
-
In theory, MPI is a relatively simple concept. It can be considered as a combination of 2 NDT methods which is magnetic flux leakage testing & visual testing
-
Considered the case of a bar magnet. It has a magnetic field in & around the magnet. Any place that a magnetic line of force exits/enters (the magnet is called a pole)
A pole where a magnetic lines of force exits the magnet as it called a north pole & a pole where the lines of force enter the magnet is called south pole
When a bar magnet is broken in the center of its length, 2 complete bar magnets appear
If the magnet is just cracked but not broken completely into 2 NP (north pole) & SP (south pole) will form at each edge of cracks
-
The magnetic field spreads out when it encounters the small air gap created by the crack because the air cannot support as much as the magnetic field per unit volume as the magnet can
When the field spreads out, it appears to leak out the materials called flux leakage field