Magnetic Patricale Testing

Question 1

MT advantages?

Answer 1

a.) Magnetic Particle Testing is the best method for detecting very fine shallow surface cracks.
b.) Magnetic Particle Testing is fast and simple.
c.) Magnetic Particle Testing does not require pre-cleaning.
d.) Magnetic Particle Testing works well through thin coatings of paint.
e.) Magnetic Particle Testing is inexpensive.

Question 2

MT disadvantage?

Answer 2

a.) The material must be Ferro-Magnetic material.
b.) The orientation and strength of Magnetic fields is critical.
c.) Magnetic Particle Testing can only detect surface and sub-surface discontinuities.
d.) Magnetic Particle Testing use high currents.
e.) Demagnetization may be required depending on post test conditions.

Question 3

6. What is a Diamagnetic metal in Magnetic Materials, and name some materials used with MPI as a process? (2)

Answer 3

a.) Diamagnetic metals have a small and negative susceptibility to magnetization and are slightly repelled.
b.) Diamagnetic metals cannot be magnetized.
c.) Copper, Silver and gold are examples of diamagnetic materials.

Question 4

7. What is a Paramagnetic metal in Magnetic Materials, and name some materials used with MPI as a process? (2)

Answer 4

a.) Paramagnetic metals have a small and positive susceptibility to magnetizations and are slightly attracted.
b.) Paramagnetic metals can be magnetized.
c.) Magnesium, molybdenum, lithium and tantalum are examples of paramagnetic materials.

Question 5

8. What is Ferromagnetic materials, and name some materials used with MPI as a process? (3)

Answer 5

a.) Has a large and positive susceptibility to magnetization.
b.) They have a strong attraction and are able to retain the magnetization after the magnetizations field has been removed.
c.) Ferromagnetic metals can be magnetized.
d.) Iron, Cobalt and Nickel are some examples of ferromagnetic metals

Question 6

Name some principles and describe the sequence that Magnetic Particle Testing can be used in.

Answer 6

a.)Magnetic Particle Testing (MPI) involves placing a magnetic fled into a part and applying Magnetic Particles to the surface.
b.) Where there is a discontinuity, the magnetic field will form north and south poles at the discontinuity.
c.) The Magnetic Particle will then be attracted to these poles and the discontinuity will become visible to the operator that is doing the inspection.

Question 7

4. Describe what the Line of Force is in Magnetic Particle Testing.

Answer 7

a.) The flow from north to south outside and south to the north from inside.
b.) Do not cross.

Question 8

5. What is a Vector Field?

Answer 8

a. It is when two magnetized field are simultaneously in the same part, the object is not magnetized in two
directions at the same time.

Question 9

Name some Magnetizing Current Characteristics Found in Magnetic Particle Testing and give a brief description of each AC Current and DC Current usage.

Answer 9

Alternating Current (AC)
a.) AC is the best method to detect surface breaking discontinuities.
Direct Current (DC).
a.) HWDC is the best way for detecting sub-surface discontinuities.

Question 10

11.Describe the term Yoke Magnetization.

Answer 10

a.) Each electromagnetic AC yoke shall have a lifting power of at least 4.5kg at maximum pole spacing that will be used.