MCQ on Powder Metallurgy Products
1. What is the pore volume in bearing materials?
A. 14-20%
B. 17-30%
C. 11-50%
D. 28-43%
Answer:: B
2. Which of the following substance is added to iron powder to improve the compressive strength of bearing?
A. Bismuth
B. Zinc
C. Copper
D. Lead
Answer:: B
3. Which of the following is not a characteristic of the bearings produced from iron?
A. Good wear resistance
B. High-oil-volume capacity
C. High porosity
D. Low-oil-volume capacity
Answer:: D
4. Copper is added to iron-copper-graphite powder mix to suppress the formation of ________
A. Cementite
B. Iron oxide
C. Copper oxide
D. Ledeburite
Answer:: A
5. What should be added to the iron powder mix to improve the speed capability?
A. Bismuth
B. Lead
C. Vanadium
D. Molybdenum
Answer:: B
6. Which of the following is not a feature of oil-impregnated bearings?
A. Excellent self-lubrication properties
B. Wide range of operating temperature
C. High-thermal expansion
D. Low-thermal expansion
Answer:: C
7. Dry bearing is made up of ______ with metal backing of _______ is available.
A. Teflon, aluminium
B. aluminium, Teflon
C. leaded bronze, aluminium
D. Teflon, bismuth
Answer:: A
8. Which kind of bearing material is suitable for oscillating and reciprocating motions?
A. Low-graphite content
B. High graphite content
C. High-oil content
D. High porosity
Answer:: B
9. What is the property of material for the application of fractional-horsepower motor bearings?
A. Moderate porosity
B. Low porosity
C. Minimum lubricating oil
D. High porosity
Answer:: D
10. The porous-metal bearings are used where re-lubrication is difficult.
A. True
B. False
Answer:: A
11. P/M bearings may be of the type ____________
A. dry type containing aluminum
B. porous type infiltrated with a lubricant
C. dry type containing teflon
D. porous type infiltrated with a lubricant, dry type containing teflon
Answer:: D
12. ________ type of porosity serves no purpose and must be minimized.
A. Moderate
B. Open
C. Closed
D. Interconnected
Answer:: C
13. Which type of porosity is connected to one another and to the external surface?
A. Moderate
B. Open
C. Closed
D. Interconnected
Answer:: D
14. _______ is obtained by subtracting the density (%) of the material from 100.
A. Hardness
B. Porosity
C. Specific gravity
D. Ductility
Answer:: B
15. _________ is possible only with the help of a pump during starting.
A. Hydrostatic lubrication
B. Boundary film lubrication
C. Hydrodynamic lubrication
D. Aerodynamic lubrication
Answer:: C
16. Under which of the following mechanisms the bearing performance depends on the ability of the lubricant to maintain a boundary film under load?
A. Hydrostatic lubrication
B. Boundary film lubrication
C. Hydrodynamic lubrication
D. Aerodynamic lubrication
Answer:: B
17. The performance factor is given by ______
A. PV
B. VF
C. AV
D. FA
Answer:: A
18. Which of the following is not a type of bearing?
A. Steel backed steel
B. Teflon bearing
C. Babbit backed steel
D. Unbacked bearings
Answer:: C
19. What is the PV value for thrust bearings?
A. 10,000
B. 50,000
C. 20,000
D. 30,000
Answer:: A
20. The load carrying capacity of bearing is expressed as the _______
A. efficiency factor
B. work factor
C. performance factor
D. capability factor
Answer:: C
21. Which of the following is not a characteristic of a P/M bearing material?
A. Ability to withstand both static and impact loads
B. Good wear characteristics
C. Good heat dissipation capacity
D. Short service life
Answer:: D
22. For bronze bearings, the amount of shrinkage _______ as the particle size of powder mix decreases.
A. decreases
B. increases
C. constant
D. moderate
Answer:: B
23. Which of the following material on addition to the powder mix lowers the strength of the bearing?
A. Oil
B. Lead
C. Bismuth
D. Graphite
Answer:: D
24. Which of the following bearing doesn’t belong to the class of non-porous bearing with steel backing?
A. Copper-antimony alloy
B. Aluminium based alloy
C. Copper based alloy
D. Babbitt
Answer:: A
25. Which of the following powder production method is used for the production of non-porous bearing with steel backing?
A. Mechanical alloying
B. Gas atomization
C. Water atomization
D. Electrolysis
Answer:: B
26. Lower lead content in copper-lead alloy is undesirable.
A. True
B. False
27. What should be amount of tin in copper-lead alloy containing 25% lead for production of non-porous bearing?
A. 14 – 20wt%
B. 4 – 10wt%
C. 1 – 5wt%
D. 11 – 15wt%
Answer:: B
28. For bronze bearings, the amount of shrinkage _______ as the particle size of powder mix decreases.
A. decreases
B. increases
C. constant
D. moderate
Answer:: B
29. Which of the following material on addition to the powder mix lowers the strength of the bearing?
A. Oil
B. Lead
C. Bismuth
D. Graphite
Answer:: D
30. Which of the following bearing doesn’t belong to the class of non-porous bearing with steel backing?
A. Copper-antimony alloy
B. Aluminium based alloy
C. Copper based alloy
D. Babbitt
Answer:: A
31. What is the compaction pressure range used for bronze bearings?
A. 775-1000 MPa
B. 500-800 MPa
C. 275-480 MPa
D. 200-300 MPa
Answer:: C
32. The microstructure of sintered copper base self-lubricating bearing consists of ________
A. pores
B. graphite particles
C. alpha phase, graphite particles
D. alpha phase, graphite particles, and pores
Answer:: D
33. Which of the following atmosphere is used for the sintering of bronze bearings?
A. Reducing
B. Oxidizing
C. Protective
D. Vacuum
Answer:: A
34. Iron base bearings are sintered at _______
A. 1500-1800°C
B. 900-1000°C
C. 800-850°C
D. 1100-1125°C
Answer:: D
35. ______ is carried out after sintering of self-lubricating bearings.
A. Sizing
B. Impregnation
C. Plating
D. Joining
Answer:: A
36. _______ are bearings containing bronze or iron powder mixed with graphite.
A. Hydrocarbon impregnated
B. Oil impregnated
C. Plastic impregnated
D. Metal impregnated
Answer:: B
37. Tin powder is made by _________
A. Atomization
B. Electrolysis
C. Reduction
D. Cold stream process
Answer:: A
38. _______ base bearings, atomized or reduced powders are employed.
A. Bismuth
B. Bronze
C. Iron
D. Tin
Answer:: C
39. Mixing of elemental powder is essential prior to compaction.
A. True
B. False
Answer:: A
40. Green density distribution is an important factor for production of porous bearings.
A. True
B. False
Answer:: A
41. Resin impregnation of porous bearings makes them _________
A. heat-treatable
B. non-heat treatable
C. reduces density
D. weak
Answer:: B
42. Oil impregnation of porous bearings is done for _____ minutes.
A. 80
B. 50
C. 30
D. 70
Answer:: C
43. Which of the following is an alternative to the immersion technique for impregnation of porous bearings?
A. Reducing impregnation
B. Grease impregnation
C. Oxidizing impregnation
D. Vacuum impregnation
Answer:: D
44. ________ bearing is used where soft journal is employed.
A. Brass bearings
B. Aluminum bearing
C. Lead bronze
D. Straight tin bronze
Answer:: C
45. The life of aluminum bearings is ________
A. 35 hours
B. > 200 hours
C. 7 hours
D. < 160 hours
Answer:: B
46. Which of the following conditions are necessary for the development of fluid film in porous bearings?
A. Viscosity
B. High speed
C. Low speed
D. High speed and viscosity
Answer:: D
47. The loss of oil occurs from the _____ in a cylindrical bearing.
A. top
B. cylindrical surface
C. ends
D. bottom
Answer:: C
48. Which of the following factors determine the rate of circulation of oil in oil-impregnated bearings?
A. Permeability of the porous bearing
B. Viscosity of the oil
C. Temperature
D. Permeability of the porous bearing, and viscosity of the oil
Answer:: D
49. The temperature of oil should not be _______ than the proper running temperature.
A. lower
B. higher
C. equal
D. very low
Answer:: B
50. The running temperature of the oil affects the ______
A. bearing performance
B. bearing life and performance
C. bearing life
D. bearing dimensions
Answer:: B
51. __________ is used in food industries.
A. P.T.F.E bearing
B. Non-porous bearing
C. Infiltrated bearing
D. Dry-lubricated bearing incorporating graphite
Answer:: C
52. _________ are employed in gearboxes.
A. Copper-lead bearings
B. Lead-tin alloy
C. Self-lubricating bearing
D. Infiltrated bearing
Answer:: A
53. Overlay layer of lead-tin alloy on copper-lead alloy has reduced fatigue properties.
A. True
B. False
Answer:: B
54. _________ are used in hot water circulating pump.
A. P.T.F.E bearing
B. Non-porous bearing
C. Infiltrated bearing
D. Dry-lubricated bearing incorporating graphite
Answer:: D
55. Which of the following is not a feature related to the P.T.F.E material for bearings?
A. Low coefficient of friction
B. Sintering temperature is 90°C
C. Sintering temperature is 900°C
D. Chemical stability from -200°C up to 300°C
Answer:: C
56. Which of the following is a drawback of the P.T.F.E material for bearings?
A. High thermal expansion
B. High thermal conductivity
C. High shear strength
D. Non-toxic
Answer:: A
57. Which of the following are methods for impregnating the metallic matrix with P.T.F.E, according to Blainey?
A. Hot pressing
B. Hot rolling, and aqueous impregnation
C. Hot rolling
D. Hot pressing, and aqueous impregnation
Answer:: D
58. Which of the following is the limitation of aqueous impregnation method?
A. Easy to get a penetration depth > 0.01”
B. Suitable for flat sheets only
C. Suitable for curved sections only
D. No loss of P.T.F.E by extrusion
Answer:: B
59. The performance of P.T.F.E /metal bearings largely depends on _________
A. Base material
B. Compacting pressure
C. Journal material
D. Sintering temperature
Answer:: C
60. DQ and DQ2 are the two types bearings produced by Glacier Metal Co. Ltd. by dispersing brass and Pb respectively.
A. True
B. False
View Answer:
Answer:: B
.
61. The ratio of interference to bore closure doesn’t rely on ______
A. density of bearing
B. rigidity of housing
C. density of shaft
D. strength of bearing
Answer:: C
62. ________ clearance for higher PV values are required.
A. Small
B. Large
C. Moderate
D. Nil
Answer:: B
