MPI EMC

Question 1

(QUESTION #3) When two pieces of steel rub against each other and either or both are in a magnetized condition, an indication is some-
times formed when magnetic particles are applied. These indications are scrawl-like, ranging from very sharp to fuzzy.

This is called (check one)
a. cracks
b. constriction
c. cold working
d. magnetic writing

Answer 1

d. magnetic writing

Question 2

(4) Indications caused by leakage fields due to internal splines, keyways, and drilled holes close to a test surface are

-defects
-nonrelevant
-magnetic writing
-boundary zones

Answer 2

nonrelevant

Question 3

(5) Sub-surface defect indications usually appear

-sharp and distinct
-sharp and wide
-wide and fuzzy
-high and loosely held

Answer 3

-wide and fuzzy

Question 4

(QUESTION #1) Place a check mark next to each material listed below which can be examined by the magnetic praticle method.
a. medium alloy steels
b. carbon steels
c. aluminum g. lead
d. magnesium
e. brass-copper
f. bronze
g. lead
h. ferro magnetic metals

Answer 4

a. medium alloy steels
b. carbon steels
h. ferro magnetic metals

Question 5

(9) In considering demagnetization, which residual field is most objectionable?
a. longitudinal
b. circular

Answer 5

a. longitudinal

Question 6

(10) Which residual field is most difficult to demagnetize?
a. longitudinal
b. circular

Answer 6

b. circular

Question 7

(11) The amount of amperage used for magnetic particle inspection using the dry, prod method is based on:
a. thickness of part
b. distance between the prods
c. diameter
d. total length of part

Answer 7

b. distance between the prods

Question 8

(12) Which is the most sensitive, continuous method or residual method?

Answer 8

continuous method

Question 9

(13) Which brings out surface indications most clearly?
a. A.C.
b. D.C

Answer 9

a. A.C.

Question 10

(14) How is the inside diameter of a cylinder best magnetized?
a. head shot
b. prods at either end
c. central conductor placed between contact heads
d. cylinder placed crosswise in solenoid

Answer 10

c. central conductor placed between contact heads

Question 11

(15) The space within and surrounding a magnetized part or conductor carrying a current is known as:
a. saturation point
b. magnetic field
c. ferromagnetic
d. paramagnetic

Answer 11

b. magnetic field

Question 12

(16) Any mass of iron, steel, or material capable of attracting other like masses is known as a ____

Answer 12

magnet

Question 13

(17) Coercive force is a material which attracts other like materials when energized with electric current. True or false

Answer 13

false

Question 14

(18) Permeability is the ease with which a metal or metallic part can be magnetized.
true or false?

Answer 14

true

Question 15

(19) A metal that is easy to magnetize is said to have high permeability.
true or false?

Answer 15

true

Question 16

(20) A metal that is difficult to magnetize is said to have high permeability.
true or false

Answer 16

false

Question 17

(23) The areas on a magnetized part from which the magnetic field is leaving or returning into the part is called:

a. salient points
b. magnetic poles
c. defect
d. field

Answer 17

c. defect

Question 18

(24) The property of magnetic metal to keep or retain a magnetic field after the magnetizing current is removed is called:

a. saturation point
b. retentivity
c. diamagnetism
d. bipolar magnetism

Answer 18

b. retentivity

Question 19

(25) The strength of a magnetic field is known as:
a. flux density
b. ferromagnetic
c. magnetic poles
d. coercive force

Answer 19

a. flux density

Question 20

(26) A sharp well defined indication is most likely to be:
a. sub-surface defect
b. surface defect

Answer 20

b. surface defect

Question 21

(29) The defect indication is strongest when the magnetic field is at a 90° angle to the defect.
true or false?

Answer 21

true

Question 22

(30) What group of materials is repelled by magnets?
a. paramagnetic
b. ferromagnetic
c. fluxematic
d. diamagnetic

Answer 22

d. diamagnetic

Question 23

(31) What group of materials is most strongly affected by magnetism and may be inspected by magnetic particle inspection?
a. diamagnetic
b. alloys
c. ferromagnetic
d. nickel based metals

Answer 23

c. ferromagnetic

Question 24

(32) When the flux lines or lines of force traverse the part in a direction essentially parallel to the long axis of the test piece,
the lines of force tend to return through the air from one pole to the other forming a closed magnetic field. This is known
as what type of magnetization?

a. circular
b. longitudinal
c. transverse
d. continuous·

Answer 24

b. longitudinal

Question 25

(33) In what manner has the part been magnetized when the magnetic flux always has a completely ferromagnetic return? a. circular b. longitudinal c. transverse d. continuous

Answer 25

a. circular

Question 26

(37) Give two causes of distorted fields.

Answer 26

1. differences in contact pressure 2. differences in surface or internal resistance 3. irregularities in configuration o(part 4. design of magnetizing equipment or application

Question 27

(39) When longitudinally magnetizing a part in a coil, how is the effective amperage determined? a. amperage applied multiplied by number of turns in coil b. number of turns in coil multiplied by width of part c. amperage indicated by ammeter d. I= E/R

Answer 27

a. amperage applied multiplied by number of turns in coil

Question 28

(41) Through what medium are discontinuities demonstrated in magnetic particle inspection? a. finely divided ferromagnetic particles of high permeability, low coercive force and very high retentivity b. finely divided ferromagnetic particles of high permeability and low retentivity c. red oil like subtance with good capillary action d. metal shavings and particles

Answer 28

b. finely divided ferromagnetic particles of high permeability and low retentivity

Question 29

(43) When the finely divided ferromagnetic particles are in oil suspension, the test method is called a. oil and Whiting technique b. oil suspension technique c. wet method d. spray or dip method

Answer 29

c. wet method

Question 30

(44) Inspecting a part by magnetizing then applying the medium is called (check one} a. continuous method b. wet method c. residual method d. dry method

Answer 30

c. residual method

Question 31

Inspecting a part by applying the suspension while the current is flowing is called (check one) a. continuous method b. dry method c. residual method d. demagnetization method

Answer 31

a. continuous method

Question 32

The flux density is always greatest (check one} a. just after the current is removed b. during the maximum current flow

Answer 32

b. during the maximum current flow

Question 33

(49) A sharp variation in the permeability of material being inspected causing a magnetic particle indication is called a (check one) a. defect b. discontinuity c. nonrelevant indication d. false indication

Answer 33

b. discontinuity

Question 34

(50) A discontinuity which will affect the service life of the part being inspected and is detrimental to its quality, appearance or performance is called a (check one) a. nonrelevant indication b. defect c. scrap d. magnetic pole

Answer 34

b. defect