Concepts of MPI (1)

Question 1

Define Leakage Fields

Answer 1

(Flux leakage or Leakage flux)
Disruptions in the magnetic field of a magnetized article (defects/discontinuities)
- Causes the uniform field to be distorted and extend into air beyond the part surface

Question 2

Why are defects/ leakage fields detectable in magnetic particle?

Answer 2

Leakage fields cause the formation of new poles with opposing polarity to the original poles.

Creates an area where lines of force are densely packed - magnetic particles become highly attracted to.

Question 3

Defects are best detected at a ___° angle to the direction of field current

Answer 3

90°

Question 4

Describe Permeabilities role in magnetic defect detection

Answer 4

Higher permeability, lower resistance to magnetization path, magnetic particles are more drown to the discontinuity and “bridge the air gap”.

Question 5

The discontinuity in a part being magnetized will cause an interruption in magnetic field, some of the field is _________ resulting in a leakage field.

Answer 5

forced into the air above the discontinuity.

size and strength of leakage field is dependant on size and orientation of the discontinuity with respect to magnetic field direction.

Question 6

What is a Dipole? and Magnetic Poles?

Answer 6

Two poles on either end of a magnetic field (N and S) known as Magnetic Poles.

Question 7

Define Consequent Poles

Answer 7

(concurrent poles) exist when more than two leakage poles are present simultaneously in a magnetized article. That establish new poles of opposite polarity to that of the original lines of force.