NEW SOUTH WALES DEPARTMENT OF EDUCATION AND TRAINING. Manufacturing and Engineering ESD. Sample Examination EA607 MAGNETIC PARTICLE TESTING

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1 Name: NEW SOUTH WALES DEPARTMENT OF EDUCATION AND TRAINING Manufacturing and Engineering ESD Sample Examination EA607 MAGNETIC PARTICLE TESTING AS3998 LEVEL B 6161J * * * * * * * Time allowed Two hours plus 10 minutes reading time PART A ATTEMPT ALL QUESTIONS PART B ATTEMPT ALL QUESTIONS PART A 2 marks per question PARTB 4 marks per question TOTAL MARKS AVAILABLE = 100 PART A ALL QUESTIONS TO BE ANSWERED ON THE EXAMINATION PAPER PART B ALL QUESTIONS TO BE ANSWERED ON THE EXAMINATION PAPER Non-programmable calculators may be used.

2 SECTION A Answer ALL questions by placing the letter representing your answer in the space provided. There is only ONE correct answer to each question. Each question 2 Marks 1. For the detection of circumferential cracks in steel rings the preferred magnetising method is: A) central conductor method B) coil C) induced current method D) parallel conductor method 2. For the detection of radial cracks in steel rings the preferred magnetising method is: A) central conductor method B) coil C) induced current method D) parallel conductor method 3. Compared to a 30 mm diameter mild steel rod tested using a head shot, a mild steel sleeve 30 mm o.d. and 20 mm i.d. tested using a central conductor would require: A) the same amperage B) a lower amperage C) a higher amperage D) higher or lower amperage depending on the relative lengths of the rod and tube 4. Fluorescent magnetic inks when compared to colour-contrast magnetic inks have: A) a higher concentration of particles B) a lower concentration of particles C) larger particles D) smaller particles

3 5. A procedure requires an alternating current of 2000A peak. If the equipment used has an ammeter indicating Root Mean Square (RMS) values, the meter should read approximately: A) 700A B) 1000A C) 1400A D) 2800A 6. Compared with alloy steels, carbon steels with the same carbon content have a: A) higher permeability and higher retentivity B) lower permeability and lower retentivity C) lower permeability and higher retentivity D) higher permeability and lower retentivity 7. Which defect type is not detectable by magnetic particle testing? A) centreline cracks in austenitic stainless steel welds B) hot tears in steel castings C) toe cracks in alloy steel weldments D) lap defects in hot rolled steel bars 8. When a ferromagnetic material is simultaneously magnetised in two directions the resulting magnetic field is termed a: A) consequent field B) distorted field C) leakage field D) vector field 9. The property of ferromagnetism can be explained in terms of atomic structures with: A) an excess of electrons B) complete outer electron shells C) paired electrons D) unpaired electrons

4 10. The part configuration which is easiest to magnetise using a magnetising coil is: A) long and narrow B) short with a large diameter C) spherical D) the part configuration has little effect on the ease of magnetisation using a coil. 11. When seeking seam defects in coil springs magnetisation should be effected using: A) a central conductor B) a coil C) a headshot D) a yoke 12. Why are materials such as lead or copper braid placed on the contact faces of heads of magnetising benches? A) because they have a lower melting point B) to provide magnetic induction C) to reduce the tendency to arcing D) to resist corrosion of the contact faces Hertz a.c. tends to flow through an article: A) evenly through the cross section of the article B) near the outside surface of the article C) near the inside surface of a hollow article D) near both the inside and outside surface of the article 14. Demagnetisation is: A) always carried out with a.c. B) always carried out with d.c. C) generally carried out with a.c., though d.c. can be used D) generally carried out with d.c., though a.c. can be used

5 15. Which of the following materials is not suited to inspection by the magnetic particle test? A) cast iron B) mild steel C) nickel D) titanium 16. Sub-surface discontinuities are best detected by: A) a.c. with wet particles B) a.c. with dry particles C) d.c. with dry particles D) d.c. with wet particles 17. When inspecting a section of varying thickness: A) use the highest amperage first B) use only circular magnetisation C) use the lowest amperage suitable to the smallest cross section first D) use wet a.c. method 18. The strength of a magnetic field within a coil is determined by: A) current in the coil B) number of turns in the coil C) the diameter of the coil D) all of the above 19. Magnetisation of a steel with high permeability is: A) impossible B) difficult C) easy D) comparable to a steel of low permeability 20. Two methods of inducing circular magnetism in an article are: A) a coil and a central conductor B) a coil and a yoke C) a central conductor and a head shot D) a central conductor and a yoke

6 21. In the magnetic flow method of inspection, magnetism is induced using: A) flexible cable B) a yoke C) prods D) a coil 22. When a field in a part of ferromagnetic material has reached a point where the field strength is no longer increased by a further increase in magnetising force the piece is said to be: A) saturated B) coerced C) retentive D) magnetic 23. Longitudinal magnetisation may be induced in a part by passing an electric current: A) along the part from end to end B) along the part using prods held against the surface and spaced about 200mm apart C) along a conductor threaded through the part D) through a coil surrounding the part 24. The magnetic properties of magnetic particle test media (particles) should include: A) high permeability, high retentivity B) high permeability, low retentivity C) low permeability, high retentivity D) low permeability, low retentivity 25. When using stationary bench equipment, the usual duration of the current shots for the current flow method is: A) as short as possible B) approximately 0.5 to 1 second C) approximately 5 seconds or longer D) the duration of the current shot is of no importance and any of the above could be used

7 26. Three causes of non-relevant indications are: A) drilled hole near the surface, very high amperage, lack of fusion B) very high amperage, drilled hole near surface, blow holes C) change of section thickness, very high amperage, drilled hole near the surface D) lack of fusion, change of section thickness, grinding cracks 27. If a current is passed through an electrical conductor, the conductor will be surrounded by: A) an electric current B) a residual field C) a magnetic field D) an eddy current field 28. Before carrying out a magnetic particle test, the part should be: A) cleaned of surface contamination to avoid false indications B) cleaned of surface contamination so the magnetic test media can enter surface discontinuities C) left in its as-received condition to avoid disturbing any defects D) thoroughly cleaned to remove any contamination that may be caught in surface cracks 29. The most difficult discontinuity to detect when carrying out a magnetic particle test is: A) a deep seated internal crack B) a surface crack C) a seam D) a subsurface crack 30. Coercive force: A) represents the reverse magnetising force necessary to remove the residual magnetism in a material B) describes the means by which the magnetic particles are suspended in the liquid when using the wet method C) is the force necessary to magnetise a part to a level required for magnetic particle testing D) describes the magnetising force used with the continuous method

8 Answer ALL questions in the space provided. SECTION B MARKS QUESTION 31 4 With the aid of a diagram briefly describe the principle of operation of the magnetic particle test. QUESTION 32 2 (a) What is the principle of the various demagnetisation methods used in magnetic particle testing? 2 (b) Outline one means of demagnetisation using a demagnetising coil. QUESTION 33 Indicate the scope of the magnetic particle test in terms of: 1½ (a) types of materials which can be tested 1½ (b) type(s) of defects detectable (in general terms) 1 (c) defect orientation

9 QUESTION 34 2 (a) Name and sketch a suitable method to magnetic particle test a mild steel sleeve, as sketched, to detect fine longitudinal cracks on the outside surface. 2 (b) Calculate the required amperage for (a). QUESTION 35 Give the advantages of using: 2 (a) a.c. current 2 (b) non-fluorescent inks for the magnetic particle test QUESTION 36 4 List TWO (2) desirable properties of magnetic particles and TWO (2) geometric properties for the magnetic particle test.

10 QUESTION 37 4 Sketch typical hystersis curves, labeling the quantities plotted for: (a) magnetic particles (b) permanent magnets. QUESTION 38 For a low fill factor magnetising coil: 1½ (a) give a formula for calculating the required current. 1½ (b) nominate the desired L / D ratio and indicate the effect of having this ratio too low. 1 (c) what length of component is considered to be adequately magnetised per magnetisation?

11 QUESTION 39 4 Briefly outline TWO (2) test variables which improve the capacity of the magnetic particle test to detect sub-surface discontinuities. QUESTION 40 Name 2 specific types of defects suited to detection by the magnetic particle test for each of the following: 1 (a) hot rolled bars 1 (b) castings 1 (c) welds 1 (d) service induced END OF EXAMINATION

MAGNETIC PARTICLE TESTING

1.Module details Module name Nominal duration MAGNETIC PARTICLE TESTING Two modules. Module codes MT02 (EA607) It is anticipated that a learner holding the prescribed entry level skills will achieve the