Thermal Processes
1. In advanced machining processes, what is the full form of EDM?
a) Electro discharge Machining
b) Electro discharge Manufacturing
c) Electrical dimensioning Machining
d) Electrode dimensions Manufacturing
Answer & Explanations
Answer: a
Explanation: Full form of EDM in advanced machining processes is, Electrodischarge machining.
2. The evolution of wire EDM took place in which part of history?
a) 1940s
b) 1950s
c) 1960s
d) 1970s
Answer & Explanations
Answer: d
Explanation: Evolution of wire EDM in 1970s was due to powerful generators, new wire electrodes, improved machining intelligence and better flushing.
3. Machining speeds have gone up to how many times after the invention of EDM?
a) Ten
b) Twenty
c) Thirty
d) Fifty
Answer & Explanations
Answer: b
Explanation: Machining speeds have gone up to 20 times after the invention of EDM.
4. By using EDM, how much percentage of machining costs can be reduced?
a) 10 %
b) 20 %
c) 30 %
d) 50 %
Answer & Explanations
Answer: c
Explanation: EDM decreased the machined cost at least by 30 %.
5. After invention of EDM, surface finish have improved by how much factor?
a) 10
b) 15
c) 20
d) 25
Answer & Explanations
Answer: b
Explanation: Surface finish have been improved by a factor of 15 after the invention of EDM.
Participate in Advanced Machining Processes Certification Contest of the Month Now!
6. Cavities with, which of the following factors can be produced using Electro discharge machining?
a) Thin walls
b) Fine features
c) Thin walls & Fine features
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: Cavities with thin walls and fine features can be machined using EDM.
7. Which of the following geometries can be machined using EDM?
a) Simple
b) Complex
c) Difficult to cut
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Electrodischarge machining can be used for simple as well as complex geometries.
8. State whether the following statement is true or false regarding EDM.
“In EDM, process is affected by hardness of material.”
a) True
b) False
Answer & Explanations
Answer: b
Explanation: EDM process is not affected by the hardness of material.
9. How much amount of burr is produced in this process?
a) 10 %
b) 40 %
c) 70 %
d) No burr
Answer & Explanations
Answer: d
Explanation: Electro discharge machining is a burr free process.
10. Which of the following mechanisms is used for material removal?
a) Electro discharge erosion
b) Magnetic abrasion
c) Electro chemical dissolution
d) Mechanical erosion
Answer & Explanations
Answer: a
Explanation: Material is removed by electro-discharge erosion (EDE) in EDM.
11. What is the value of order of frequency applied between the two electrodes in EDM?
a) 1 kHz
b) 3 kHz
c) 5 kHz
d) 7 kHz
Answer & Explanations
Answer: c
Explanation: The magnitude of frequency applied between the electrodes in EDM is about 5 kHz.
12. What are the magnitude of voltages used in Electro discharge machining?
a) 1 to 20 V
b) 20 to 120 V
c) 120 to 220 V
d) 220 to 320 V
Answer & Explanations
Answer: b
Explanation: In EDM, the magnitude of voltages range between 20 and 120 V.
13. What are the values of gaps between the electrodes in EDM?
a) 0.001 – 0.05 mm
b) 0.01 – 0.5 mm
c) 0.1 – 5 mm
d) 1 – 15 mm
Answer & Explanations
Answer: b
Explanation: In EDM, very small gaps that range between 0.01 – 0.5 mm are maintained.
14. How is material removed in Electro discharge machining?
a) Melt and evaporate
b) Corrode and break
c) Mechanical erosion takes place
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: In Electro discharge machining, material is melted and then evaporated.
15. What is the radius of channel, when electrical breakdown occur?
a) 4 µm
b) 6 µm
c) 8 µm
d) 10 µm
Answer & Explanations
Answer: d
Explanation: In EDM, the electrical breakdown occurs in dielectric in a channel of radius about 10 µm.
Get Free Certificate of Merit in Advanced Machining Processes Now!
16. State whether the following statement is true or false regarding EDM.
“In EDM, negative ions (electrons) collide with positive ions to generate heat.”
a) True
b) False
Answer & Explanations
Answer: b
Explanation: In Electro discharge machining, electrons collide with neutral atoms producing positive ions and further electrons.
17. What are the values of temperature that are obtained while machining using EDM?
a) 2000 to 3000ᵒC
b) 4000 to 6000ᵒC
c) 8000 to 12000ᵒC
d) 15000 to 20000ᵒC
Answer & Explanations
Answer: c
Explanation: The temperatures obtained when the ions reach their respective electrodes, range between 8000ᵒC and 12000ᵒC.
18. What range of heat fluxes are obtained while machining using EDM?
a) 1017 W/m2
b) 1019 W/m2
c) 1024 W/m2
d) 1027 W/m2
Answer & Explanations
Answer: a
Explanation: Heat flux up to the value of 1017 W/m2 are obtained in EDM.
19. What is the duration of sparks that are produced in Electro discharge machining?
a) 0.001 – 1 µs
b) 0.1 – 2000 µs
c) 0.2 – 100 ms
d) 100 – 2000 ms
Answer & Explanations
Answer: b
Explanation: Duration of spark in Electro discharge machining is about 0.1 to 2000 µs.
20. State whether the following statement is true or false about material removal in EDM.
“In EDM, high pressures allow the metal to evaporate.”
a) True
b) False
Answer & Explanations
Answer: b
Explanation: High pressures in EDM try to prevent the super-heated metal from evaporation.
21. What are the values of pressure of the plasma in EDM?
a) Up to 2 atm
b) Up to 20 atm
c) Up to 200 atm
d) Up to 2000 atm
Answer & Explanations
Answer: c
Explanation: Pressure on the plasma channel rises to values as high as 200 atm when dielectric evaporates.
22. At the end of pulse, super-heated metal evaporates _______________
a) Explosively
b) Normally
c) Periodically
d) Occasionally
Answer & Explanations
Answer: a
Explanation: At the end of pulse, pressure drops suddenly and super-heated metal evaporates explosively.
23. After the explosion is over, how is the debris carried away?
a) Evaporation
b) Fresh dielectric
c) Old dielectric
d) All of the mentioned
Answer & Explanations
Answer: b
Explanation: Debris is carried away by the fresh dielectric that rushes in.
24. The layer formed when unexpelled molten metal solidifies is known as _______________
a) Reabsorbed layer
b) Recast layer
c) Unevaporated layer
d) Condensed layer
Answer & Explanations
Answer: b
Explanation: Unexpelled molten metal solidifies to form a layer known as recast layer.
25. Amount of material removed from anode and cathode depend on which of the following?
a) Electrons
b) Positive ions
c) Electrons & Positive ions
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: The amount of material removed from electrodes depend on the contribution of the charged ions.
26. What happens when the electron current predominates in the discharge?
a) More anodic removal
b) More cathodic removal
c) Remains same
d) All of the mentioned
Answer & Explanations
Answer: a
Explanation: When electron current predominates the electrical discharge, anodic material removal is greater than cathodic material.
27. Between what values mentioned below, do the discharges and sparks usually vary?
a) 1 and 10,000
b) 500 and 500,000
c) 500,000 and 1,000,000
d) None of the mentioned
Answer & Explanations
Answer: b
Explanation: Frequency of discharges or sparks generally vary between 500 and 500,000 sparks per second.
Take Advanced Machining Processes Tests Now!
28. What is the value of gap maintained between the electrodes when we use servo mechanism?
a) 10 – 100 µm
b) 100 – 200 µm
c) 200 – 500 µm
d) 500 – 1000 µm
Answer & Explanations
Answer: c
Explanation: In EDM, value of gap maintained between the electrodes range between 200 and 500 µm.
29. Based on the electrode gap, which of the following electric pulses are generated?
a) Open Circuit pulses
b) Sparks
c) Arcs
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Based on the electrode gap, electric pulses are distinguished which are – circuit pulses, sparks, arcs and short circuits.
30. State whether the following statement is true or false regarding EDM.
“In Electro discharge machining, electric pulses generated affect the material removal.”
a) True
b) False
Answer & Explanations
Answer: a
Explanation: In Electro discharge machining, electric pulses generated have an impact on the material removal.
31. Open gap voltages contribute to how much amount of material removal?
a) 20 %
b) 50 %
c) 70 %
d) No contribution
Answer & Explanations
Answer: d
Explanation: Open gap voltage that occur at too large distances do not contribute to any material removal.
32. When the electrode gap is too small or electrodes are in contact, how much material is removed?
a) 10%
b) 20%
c) 30%
d) No material removed
Answer & Explanations
Answer: d
Explanation: When electrodes come in contact with one another, short circuits occur and material removed is not possible.
33. Which components mentioned below are affected due to arcs?
a) Work piece
b) Tool
c) Work piece & Tool
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: Arcs are believed to occur at same spots on electrode surfaces which damage both tool and work piece.
34. Which of the following pulses contribute to the desired material removal in EDM?
a) Open circuit pulses
b) Short circuits
c) Arcs
d) Sparks
Answer & Explanations
Answer: d
Explanation: The sparks are the one which contributes to the desired material removal in Electro discharge machining.
35. Which of the following are main components of EDM?
a) Dielectric system
b) Servomechanism
c) Power supply
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Main components of machining system in EDM are – dielectric system, power supply and servomechanism.
36. What is the function of feed-control system in Electro discharge machining?
a) Constant gap
b) Supply power
c) Dielectric fluid supply
d) Work piece holding
Answer & Explanations
Answer: a
Explanation: Feed control system is used to maintain constant gap between electrodes.
37. What is the use of power supply system in Electro discharge machining?
a) Constant gap
b) Supply power
c) Dielectric fluid supply
d) Work piece holding
Answer & Explanations
Answer: b
Explanation: Power supply system is used to supply pulses at certain voltages, current, on time and off time.
38. What is the function of dielectric circulation unit in Electro discharge machining?
a) Constant gap
b) Supply power
c) Dielectric fluid supply
d) Work piece holding
Answer & Explanations
Answer: c
Explanation: Dielectric circulation unit is used to supply dielectric fluid for flushing.
39. Which of the following materials are used as electrodes in EDM?
a) Graphite
b) Copper
c) Brass
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: All the materials mentioned above, can be used as electrodes in Electro discharge machining.
40. Metals with _________ melting point and _________ electrical conductivity are chosen as tools in EDM.
a) Low, good
b) Low, bad
c) High, good
d) High, bad
Answer & Explanations
Answer: c
Explanation: In EDM, metals with high melting point and good electrical conductivity are used as tools.
41. Copper has _________ Electro discharge machining wear and _________ conductivity.
a) Good, better
b) Good, worse
c) Bad, better
d) Bad, worse
Answer & Explanations
Answer: a
Explanation: Cu is the metal which has better conductivity and good electro discharge machining wear.
42. Which of the following tungsten carbides are used as electrodes in EDM?
a) Silver tungsten
b) Copper tungsten
c) All of the mentioned
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: Both Silver tungsten and copper tungsten are the tungsten carbides used in EDM.
43. State whether the following statement is true or false regarding materials used in Electro discharge machining.
“In metals, copper graphite has less electrical conductivity than graphite.”
a) True
b) False
Answer & Explanations
Answer: b
Explanation: Copper graphite has better electrical conductivity than graphite.
44. Brass metal ensures which type of sparking conditions in Electro discharge machining?
a) Stable
b) Unstable
c) Unsteady
d) Insecure
Answer & Explanations
Answer: a
Explanation: Brass is a type of metal which ensures stable sparking conditions in Electro discharge machining.
45. In addition to the feed of tool, Electro discharge machining tool can have which type of motion?
a) Oscillatory
b) Rotary
c) Vibrational
d) All of the mentioned
Answer & Explanations
Answer: b
Explanation: In addition to feed, the tool electrode may have rotary or orbiting motion.
46. Which of the following parameters determines the size of cavities?
a) Size of electrode
b) Radius of orbit
c) All of the mentioned
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: Size of electrode and radius of orbit determines the size of cavities in EDM.
47. Electrode orbiting ________ the flushing of dielectric fluid in Electro discharge machining.
a) Improves
b) Decreases
c) Reduces
d) Degrades
Answer & Explanations
Answer: a
Explanation: The additional orbiting motion of electrodes helps in improving the flushing by creating a pumping effect of dielectric liquid.
48. Quality of hole produced by orbiting motion is _________ to that obtained by using stationary electrode.
a) Inferior
b) Superior
c) Lower
d) All of the mentioned
Answer & Explanations
Answer: b
Explanation: Quality of hole produced by orbiting motion is superior to that obtained by using stationary electrode.
49. In EDM, electrode polarity depends up on which of the following components?
a) Work piece
b) Electrode material
c) All of the mentioned
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: In Electro discharge machining, electrode polarity depends on both work piece and electrode material.
50. Which one among the following, is the most important factor in determining the tool wear?
a) Melting point
b) Boiling point
c) Power supplied
d) Feed rate
Answer & Explanations
Answer: a
Explanation: In EDM, melting point is the most important factor in determining the tool wear.
51. Electrode wear ratios can be expressed as, which of the following wears?
a) End wear
b) Side wear
c) Corner wear
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Electrode wear ratios are expressed as end wear, corner wear, side wear and volume wear.
52. The term no wear in EDM occurs when electro-to-work piece wear ratio is __________
a) <1%
b) <3%
c) <5%
d) <10%
Answer & Explanations
Answer: a
Explanation: In Electro discharge machining, no wear is the term used when the electrode-to-work piece ratio is less than 1%.
53. Which of the following are the other factors that influence the electrode wear?
a) Voltage
b) Current
c) Electrode material
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: In EDM, electrode wear depends on the factors such as voltage, current, electrode material and polarity.
54. State whether the following statement is true or false regarding wear in EDM.
“In EDM, electrode wear is less dominant when it comes to micromachining applications.”
a) True
b) False
Answer & Explanations
Answer: b
Explanation: Electrode wear is more when it comes to micromachining applications in EDM.
55. State whether the following statement is true or false regarding wear in EDM.
“In EDM, corner wear ratio does not depend on type of electrode material.”
a) True
b) False
Answer & Explanations
Answer: b
Explanation: In EDM, corner wear ratio depend on the material of electrode used.
56. In Electro discharge machining, highest wear ratio is associated with which type of melting point?
a) Low
b) Medium
c) High
d) Very high
Answer & Explanations
Answer: a
Explanation: In Electro discharge machining, lowering of the melting point of electrode material results in high wear ratio.
57. Which of the following is not a function of dielectric in EDM?
a) Flush particles
b) Cool the section
c) Maintain voltage
d) Provide insulation
Answer & Explanations
Answer: c
Explanation: Flushing particles, providing insulation and cooling the sections that are heated, are the functions of dielectric.
58. Which of the following are the main requirements of dielectric fluids?
a) Viscosity
b) High flash point
c) Minimum odour
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Adequate viscosity, high flash point, oxidation stability, minimum odour, low cost and good electrical discharge are the main requirements of dielectric fluids.
59. Which of the following can be used as dielectric fluids in EDM?
a) Kerosene
b) Silicon fluids
c) Distilled water
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: The dielectric fluids used are kerosene, silicon fluid, ethylene glycol, water in emulsions and distilled water.
60. In EDM, inadequate flushing will not result in which of the following consequences?
a) Arcing
b) Debris removal
c) Decrease electrode life
d) Increased production time
Answer & Explanations
Answer: b
Explanation: Inadequate flushing in Electro discharge machining results in less removal or no removal of debris.
61. Which methods below, are used for introducing the dielectric in machining gap?
a) Normal flow
b) Reverse flow
c) Jet flushing
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Four methods namely normal flow, reverse flow, jet flushing and immersion flushing are used for introducing dielectric.
62. Few large holes are _________ than many small flushing holes in Electro discharge machining.
a) Worse
b) Better
c) Well
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: Many small holes are better than a few large holes in machining thorough the EDM process.
63. State whether the following statement is true or false regarding the dielectric in EDM.
“In EDM, flushing through the tool is more preferred than side flushing.”
a) True
b) False
Answer & Explanations
Answer: a
Explanation: Flushing through the tool is preferred than side flushing for deep cuts.
64. In Electro discharge machining, which type of dielectric flow mentioned below is desirable?
a) Unsteady flow
b) Steady flow
c) Unstable flow
d) None of the mentioned
Answer & Explanations
Answer: b
Explanation: In EDM, steady dielectric flow on the entire electrode-work piece interfaces is most desirable.
65. Metal is removed on which of the components in electro discharge machining?
a) Electrode tool
b) Work piece
c) Electrode tool & Work piece
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: In Electro discharge machining, material is removed from both tool and work piece.
66. On which of the following components, does the MRR depend?
a) Work piece
b) Electrode tool
c) Electrode tool & Work piece
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: Material removal rate not only depends on work piece material but also the tool material.
67. Which of the following factors influence the material removal rate?
a) Pulse condition
b) Electrode polarity
c) Machining medium
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: The factors such as pulse conditions, electrode polarity and machining medium also affect the material removal rate.
68. In Electro discharge machining, materials with low melting point have which type of material removal rate?
a) Very low
b) Low
c) Medium
d) High
Answer & Explanations
Answer: d
Explanation: In Electro discharge machining, materials having low melting point have high material removal rates and vice-versa.
69. In Electro discharge machining, materials with low melting point have which type of surface roughness?
a) Rough
b) Smooth
c) Fine
d) All of the mentioned
Answer & Explanations
Answer: a
Explanation: In Electro discharge machining, materials having low melting point have high rougher surfaces and vice-versa.
Take Advanced Machining Processes Tests Now!
70. What are the values of material removal rates in EDM?
a) 0.001 to 0.1 mm3/min
b) 0.1 to 400 mm3/min
c) 400 to 1000 mm3/min
d) 1000 to 5000 mm3/min
Answer & Explanations
Answer: b
Explanation: In EDM, material removal rates range from 0.10 to 400 mm3/min.
71. What happens to the material removal rate if the sparks are very less in EDM?
a) Decreases
b) Increases
c) Increase and then decrease
d) All of the mentioned
Answer & Explanations
Answer: a
Explanation: In EDM, if sparks generated are less then material removal rate decreases.
72. What is the relation between the melting point and the material removal rate?
a) Directly Proportional
b) Inversely proportional
c) Indirectly proportional
d) None of the mentioned
Answer & Explanations
Answer: b
Explanation: In Electro discharge machining, material removal rate is inversely proportional to the melting point.
73. What happens to the crater size if we increase the current keeping the pulse time constant?
a) Increase
b) Decrease
c) Decrease and increase
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: By keeping pulse time constant and increasing current, crater size also increases.
74. What happens to the crater size if we decrease the pulse time keeping the current constant?
a) Increase
b) Decrease
c) Increase and decrease
d) None of the mentioned
Answer & Explanations
Answer: b
Explanation: By decreasing pulse time and keeping current constant, crater size also decreases.
75. On which of the following factors do the craters depend?
a) Physical properties
b) Mechanical properties
c) Composition of medium
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: In EDM, craters depend on the physical and mechanical properties of material and composition of medium.
76. The maximum depth of damaged layer is how many times that of average surface roughness?
a) 1.5 time
b) 2 times
c) 2.5 times
d) 3 times
Answer & Explanations
Answer: c
Explanation: Depth of damaged layer is two and half times the average surface roughness value.
77. What happens to the surface roughness values if the MRR increases in EDM?
a) Increases
b) Decreases
c) Decrease and increase
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: In EDM, the surface roughness values increases linearly with increase in the material removal rates.
78. State whether the following statement is true or false regarding the surface roughness in EDM.
“In EDM, graphite electrodes produce smoother surfaces than metal ones.”
a) True
b) False
Answer & Explanations
Answer: b
Explanation: In EDM, graphite electrodes produce rougher surfaces than that of the metal ones.
79. In Electro discharge machining, what happens to the surface finish if the pulse energy is decreased?
a) Reduces
b) Decreases
c) Improves
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: In Electro discharge machining, the surface finish improves if the pulse energy is decreased.
80. Using of a mate electrode in Electro discharge machining _____________ the surface roughness of material.
a) Increases
b) Decreases
c) Enhances
d) None of the mentioned
Answer & Explanations
Answer: b
Explanation: By using a mate electrode in Electro discharge machining, the surface roughness values are decreased.
81. What happens to the surface roughness if oxygen gas is introduced in the gap?
a) Increases
b) Decreases
c) Decrease and then increase
d) All of the mentioned
Answer & Explanations
Answer: b
Explanation: In EDM, surface roughness increases with the supply of oxygen gas in gaps.
82. By how much percent surface roughness is reduced if we use proper dielectric flow?
a) 25%
b) 50%
c) 75%
d) 100%
Answer & Explanations
Answer: b
Explanation: In Electro discharge machining, if we use a proper dielectric fluid flow, surface roughness is decreased by 50 percent.
83. What are the tolerance values obtained by machining using EDM?
a) ± 10 mm
b) ± 15 mm
c) ± 25 mm
d) ± 40 mm
Answer & Explanations
Answer: c
Explanation: The tolerance values of ± 25 mm are obtained when we machine components using EDM.
84. How much extra tolerances are achieved when we choose proper variables?
a) ± 5 mm
b) ± 10 mm
c) ± 15 mm
d) ± 20 mm
Answer & Explanations
Answer: a
Explanation: Extra tolerances of ± 5 mm are obtained with a proper choice of process variables.
85. What are the values of temperatures obtained in Electro discharge machining?
a) 1000 to 2000 oC
b) 2000 to 4000 oC
c) 4000 to 8000 oC
d) 8000 to 12000 oC
Answer & Explanations
Answer: d
Explanation: The temperature attained while machining in Electro discharge machining are from 8000 to 12000 oC.
86. What is the value of thickness of recast layer obtained when power of 5 µJ is given?
a) 1 µm
b) 3 µm
c) 5 µm
d) 7 µm
Answer & Explanations
Answer: a
Explanation: When a power of 5 µJ is given, recast layer thickness of 1 µm is obtained.
87. What are the values of thickness of recast layers in Electro discharge machining?
a) 0.001 to 0.025 µm
b) 0.01 to 0.25 µm
c) 1 to 25 µm
d) 10 to 250 µm
Answer & Explanations
Answer: c
Explanation: In Electro discharge machining, the value of thickness of recast layers ranges from 1 to 25 µm.
88. In Electro discharge machining, some annealing of the work piece can be expected __________ the machined surface.
a) On
b) Just below
c) Above
d) At bottom
Answer & Explanations
Answer: b
Explanation: Annealing of some part of the work piece in EDM can be expected just below the machined surface.
89. The depth of the annealed surface is __________ to the amount of power used in machining operation.
a) Directly proportional
b) Inversely proportional
c) Exponential
d) All of the mentioned
Answer & Explanations
Answer: a
Explanation: The depth of annealed surface in EDM is proportional to the amount of power used.
Participate in Advanced Machining Processes Certification Contest of the Month Now!
90. What are the values of thickness of annealed surface obtained while machining using EDM?
a) 1 to 25 µm
b) 50 to 200 µm
c) 200 to 500 µm
d) 500 to 1000 µm
Answer & Explanations
Answer: b
Explanation: Values of annealed surface thickness range from 50 µm to 200 µm.
91. In EDM, choosing electrodes that produce which type of machining reduces the annealing effect?
a) Stable
b) Unstable
c) Uneven
d) All of the mentioned
Answer & Explanations
Answer: a
Explanation: In Electro discharge machining, choosing the electrodes which produce more stable machining reduces the annealing effect.
92. What happens to the fatigue strength of alloys if altered surfaces are produced in Electro discharge machining?
a) Increases
b) Reduces
c) Enhances
d) Improves
Answer & Explanations
Answer: b
Explanation: The altered surface layers that are produced in Electro discharge machining, significantly reduces the fatigue strength of alloys.
93. The altered layers formed during the process of EDM consists of which of the following?
a) Tempered layers
b) Heat affected zones
c) Intergranular precipitates
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Altered layers consists of recast layers, tempered layers, HAZs and intergranular precipitates in EDM.
94. During roughing process through Electro discharge machining, what is the thickness of layer formed?
a) <0.075 mm
b) <0.125 mm
c) <0.500 mm
d) <0.750 mm
Answer & Explanations
Answer: b
Explanation: The thickness of layer obtained after machining is <0.127 mm in EDM.
95. During finishing process through Electro discharge machining, what is the value thickness of layer formed?
a) <0.075 mm
b) <0.125 mm
c) <0.500 mm
d) <0.750 mm
Answer & Explanations
Answer: a
Explanation: The thickness of layer obtained during EDM finishing is <0.075 mm.
96. Which of the following processes can be used for restoration of fatigue properties?
a) Low-stress grinding
b) Chemical machining
c) Reheat treatment
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: For removal of altered layers processes such as low-stress grinding, chemical machining, reheat treatment, metallurgical type coating and application of shot peening.
97. State whether the following statement is true or false regarding the HAZ in EDM.
“In EDM, post treatment to recover fatigue strength is not recommended.”
a) True
b) False
Answer & Explanations
Answer: b
Explanation: After machining using EDM, post treatment to restore the fatigue strength is recommended.
98. Which of the following shapes can be produced using Electro discharge machining?
a) Complex shapes
b) Simple shapes
c) All of the mentioned
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: Electro discharge machining is used to machine complex shapes to a high degree of accuracy.
99. Which of the following materials can be machined using Electro discharge machining?
a) Heat resistant alloys
b) Super alloys
c) Carbides
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: EDM is used to machine materials such as carbides, heat resistant and super alloys which are difficult-to-machine materials.
100. Which of the following are the applications of Electro discharge machining?
a) Holes
b) Slots
c) Texturing
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Micromachining of holes, slots, dies, texturing, milling, surface modification and mechanical pulsing are some typical applications of Electro discharge machining.
101. State whether the following statement is true or false regarding the applications of EDM.
“In advanced machining processes, the incorporation of EDM with CIM increased the length of time for unit operation.”
a) True
b) False
Answer & Explanations
Answer: b
Explanation: The incorporation of EDM in CIM reduced the length of time per unit operation.
102. Which type of electrode is used for drilling in Electro discharge machining?
a) Flat electrode
b) Cuboidal electrode
c) Tubular electrode
d) Spherical electrode
Answer & Explanations
Answer: c
Explanation: Tubular electrode is mostly preferred in Electro discharge machining, for drilling purpose.
Take Advanced Machining Processes Practice Tests – Chapterwise!
Start the Test Now: Chapter 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
103. The dielectric fluid is flushed in thorough which part of the electrode in drilling in EDM?
a) Interior hole
b) Side gaps
c) All of the mentioned
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: EDM drilling uses a tubular electrode which flushes the dielectric thorough the interior holes for removing debris.
104. Which type of holes can be produced through drilling using Electro discharge machining?
a) Irregular
b) Curved
c) Tapered
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Drilling of work piece using EDM produced holes which can be irregular, curved, tapered as well as inclined holes.
105. What are the values of general feed rates used for drilling in EDM?
a) 0.1 mm/min
b) 0.3 m/min
c) 0.5 mm/min
d) 0.7 mm/min
Answer & Explanations
Answer: a
Explanation: Usually a feed rate of 0.10 mm/min is used for drilling the work piece using Electro discharge machining.
106. What are range of diameter values obtained by drilling using EDM?
a) 0.01 to 0.05 mm
b) 0.1 to 0.5 mm
c) 1 to 5 mm
d) 10 to 15 mm
Answer & Explanations
Answer: b
Explanation: Diameter values while drilled using Electro discharge machining, ranges from 0.10 to 0.50 mm.
107. What are the values of overcuts left behind after drilling of work piece?
a) 0.01 to 0.05 mm
b) 0.1 to 0.5 mm
c) 1 to 5 mm
d) 10 to 15 mm
Answer & Explanations
Answer: a
Explanation: Overcut values from 0.01 to 0.05 mm are obtained after the drilling process in EDM.
108. Electro discharge sawing is an application of EDM which employs __________ as tool material.
a) Steel band
b) Disc
c) Steel band & Disc
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: Electro discharge sawing is an application of EDM which employs either steel band or disc as tool.
109. When compared to the conventional abrasive sawing, how many times faster is the MRR?
a) Twice
b) Thrice
c) Four
d) Five
Answer & Explanations
Answer: a
Explanation: Electro discharge sawing cuts the work piece material at the rates which are twice that of conventional abrasive sawing method.
110. How much amount of burr is produce while machined using Electro discharge sawing?
a) 10%
b) 20%
c) 50%
d) No Burr
Answer & Explanations
Answer: d
Explanation: The cuts produced in Electro discharge sawing have smaller kerf widths which hav no burrs in it.
111. What are the values of finish obtained by machining work piece thorough Electro discharge sawing?
a) 0.1 to 4 µm
b) 6.3 to 10 µm
c) 12.4 to 23 µm
d) 25.6 to 40 µm
Answer & Explanations
Answer: b
Explanation: The finish obtained ranges from 6.3 to 10 µm when machined using Electro discharge sawing.
112. What are the recast layer thickness values obtained in ED sawing?
a) 0.001 to 0.022 mm
b) 0.025 to 0.130 mm
c) 0.236 to 0.352 mm
d) 0.432 to 0.568 mm
Answer & Explanations
Answer: b
Explanation: The recast layer thickness values obtained from ED sawing range from 0.025 to 0.13 mm.
113. Which of the following electrodes are used for machining spherical surfaces in Electro discharge machining?
a) Tubular electrodes
b) Flat electrodes
c) Cuboidal electrodes
d) All of the mentioned
Answer & Explanations
Answer: a
Explanation: Simple tubular electrodes are used to machine convex and concave spherical surfaces.
114. What are the values of dimensional accuracy obtained while machining spherical surfaces?
a) ± 1 µm
b) ± 3 µm
c) ± 5 µm
d) ± 7 µm
Answer & Explanations
Answer: a
Explanation: Dimensional accuracy of ± 1 µm is obtained while machining spherical surfaces using EDM.
115. What are the surface roughness values obtained while machining spherical surfaces using Electro discharge machining?
a) <0.1 µm
b) <0.3 µm
c) <0.5 µm
d) <0.7 µm
Answer & Explanations
Answer: a
Explanation: The surface roughness values obtained while machining of spherical surfaces are <0.1 µm in Electro discharge machining.
116. Which motion of tool is used for machining spherical surfaces in Electro discharge machining?
a) Oscillatory
b) Vibratory
c) Rotary
d) All of the mentioned
Answer & Explanations
Answer: c
Explanation: The rotary motion tool is used for machining spherical surfaces of conducting ceramic materials in EDM.
117. Which type of electrodes are used for milling application in Electro discharge machining process?
a) Tubular type electrodes
b) Cylindrical type electrodes
c) Flat type electrodes
d) Spherical type electrodes
Answer & Explanations
Answer: b
Explanation: Standard cylindrical electrodes are used for milling application in EDM process.
118. Which type of cavities can be machined using milling process by Electro discharge machining?
a) Complex cavities
b) Simple cavities
c) Simple & Complex cavities
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: Simple cavities and complex cavities are machined by successive NC sweeps of electrode over the desired path.
119. The simple electrodes are rotated at which speed for milling of work pieces in Electro discharge machining?
a) Very low
b) Low
c) Medium
d) High
Answer & Explanations
Answer: d
Explanation: Simple electrodes are rotated at high speeds for milling in Electro discharge machining same as that of conventional milling.
120. What happens to the dielectric flushing while milling tool is rotated at a high speed in EDM?
a) Improved
b) Worsen
c) Reduced
d) All of the mentioned
Answer & Explanations
Answer: a
Explanation: Milling by electro discharge machining enhances the dielectric flushing due to high speed rotation of tool.
121. State whether the following statement is true or false regarding the applications of EDM.
“In EDM, milling process can machine complex shapes with sharp corners.”
a) True
b) False
Answer & Explanations
Answer: b
Explanation: EDM milling has a main limitation i.e.., it cannot machine complex shapes with sharp tools because of rotating tool.
122. Which of the following are the steps included in the die sinking process of EDM?
a) CAD of electrode
b) Electrode manufacturing
c) Programming for die sinking
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Designing of electrode, then manufacturing, and programming of die sinking are the steps to be followed for die sinking process in EDM.
123. Wire EDM is a special form of Electro discharge machining which contains __________ electrode.
a) Continuously moving
b) Periodically moving
c) Discontinuously moving
d) All of the mentioned
Answer & Explanations
Answer: a
Explanation: Wire EDM is a special type of EDM which uses a continuously moving electrode for removal of material.
124. Which path of the components in wire EDM determines the path to be machined?
a) Horizontal worktable movement
b) Vertical worktable movement
c) Horizontal & Vertical worktable movement
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: Horizontal movement of the work table determines the path to be machined in Wire Electro discharge machining.
125. Which of the following materials are machined using Wire Electro discharge machining?
a) Polycrystalline diamond
b) Cubic Boronitride
c) Matrix composites
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Polycrystalline diamond (PCD), cubic boron nitride (CBN) and other matrix composites are the material than can be machined using wire EDM.
126. How much amount of burr is produce when we use Wire Electro discharge machining for machining of work pieces?
a) 10%
b) 20%
c) No burr
d) Small amount
Answer & Explanations
Answer: c
Explanation: In Wire Electro discharge machining no burr is produced without any distortion while machining work pieces.
127. Which of the following industries use wire EDM for different applications?
a) Chemical industry
b) Aerospace industry
c) Automobile industry
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Industries such as chemical, aerospace, automobile, nuclear etc.., use wire EDM for a wide variety of applications in their industries.
128. While machining insulating ceramic materials using EDM, where is the sheet metal placed?
a) Over material
b) Below material
c) Under material
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: Sheet metal is placed over the material in machining of insulating materials using EDM.
129. Sparks occur between which of the following components?
a) Work piece and sheet metal
b) Tool electrode and sheet metal
c) Work piece and electrode
d) None of the mentioned
Answer & Explanations
Answer: b
Explanation: Sparks occur between sheet metal and tool electrode for macining insulating ceramics.
130. Texturing is applied to the steel sheets at which stages of cold rolling?
a) Initial stages
b) Middle stages
c) Final stages
d) All of the mentioned
Answer & Explanations
Answer: a
Explanation: At the final stages of cold rolling, texturing is applied to the steel sheets.
131. What is the full form of EDT in EDM processes?
a) Electro discharge Tinplating
b) Electro discharge Texturing
c) Electro discharge Tapping
d) Electro discharge Turing
Answer & Explanations
Answer: b
Explanation: Electro Discharge Texturing is a variant of EDM which is the full form of EDT.
132. Which of the following are the process variables for texturing process in EDM?
a) Pulse current
b) Electrode polarity
c) Dielectric type
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Pulse current, polarity, dielectric, electrode material and roll rotation speed are some process variables of texturing.
Participate in Advanced Machining Processes Certification Contest of the Month Now!
133. What are the values of current amplitudes used in EDT?
a) 0.2 to 1 A
b) 2 to 10 A
c) 20 to 100 A
d) 40 to 200 A
Answer & Explanations
Answer: b
Explanation: The values of current amplitudes in EDT range from 2 to 10 A.
134. What are duration values of current amplitude in EDT?
a) 0.1 to 1 µs
b) 1 to 10 µs
c) 10 to 100 µs
d) 100 to 1000 µs
Answer & Explanations
Answer: c
Explanation: Duration of current amplitudes used for EDT range from 10 to 100 µs.
135. What are the spindle rotation speeds used in EDT?
a) 1 to 4 rpm
b) 10 to 40 rpm
c) 20 to 60 rpm
d) 30 to 90 rpm
Answer & Explanations
Answer: b
Explanation: Spindle rotation speeds for EDT process range from 10 to 40 rpm.
136. What are the values of diameter which are machined using Micro-EDM?
a) 0.001 to 0.01 mm
b) 0.01 to 0.1 mm
c) 0.1 to 1 mm
d) 1 to 10 mm
Answer & Explanations
Answer: c
Explanation: Values of diameter in Micro-EDM range from 0.10 to 1.0 mm.
137. What happens to the machine capital cost in EDT when there is an increase in tool quantity?
a) Decreases
b) Increases
c) Remains same
d) None of the mentioned
Answer & Explanations
Answer: b
Explanation: With increase in tools quantity machine cost increases but texturing cost reduces.
138. What is the value of depth to diameter ratio in Micro-Electro discharge machining process?
a) 10:1
b) 5:2
c) 4:3
d) 2:1
Answer & Explanations
Answer: a
Explanation: Value of the depth to diameter ratio in Micro-Electro discharge machining is about 10:1.
139. What are the values of depths that can be machined using Micro-EDM?
a) 1 mm
b) 10 mm
c) 100 mm
d) 1000 mm
Answer & Explanations
Answer: c
Explanation: Micro-Electro discharge machining can machine up to a depth of 100 mm in the work piece material.
140. What are the machining rates used in Micro-EDM process?
a) 0.1 to 2 mm/min
b) 1 to 20 mm/min
c) 10 to 200 mm/min
d) 100 to 500 mm/min
Answer & Explanations
Answer: b
Explanation: Machining rates used in Micro-EDM process range from 1 to 20 mm/min.
141. What are the values of hole diameters obtained using Wire electro discharge grinding?
a) 1 µm
b) 3 µm
c) 5 µm
d) 7 µm
Answer & Explanations
Answer: c
Explanation: Values of hole diameters up to 5 µm can be obtained using Wire electro discharge grinding process.
142. What are the feed rates used in WEDG process?
a) 1 to 5 mm/min
b) 5 to 10 mm/min
c) 10 to 15 mm/min
d) 15 to 20 mm/min
Answer & Explanations
Answer: b
Explanation: Feed rate values in WEDG process range from 5 to 10 mm/min.
143. Which of the following is a major difficulty in the Electro discharge machining process?
a) Proper sparks
b) Abnormal discharges
c) Optimum feed rates
d) No burr
Answer & Explanations
Answer: b
Explanation: Avoidance of abnormal discharges has become a major difficulty in Electro discharge machining process.
144. What has been done to the off time when there is a no-load voltage of electric discharge?
a) Increased
b) Decreased
c) Reduced
d) Remains same
Answer & Explanations
Answer: a
Explanation: The off time of pulse is increased in order to avoid the abnormal electric discharges.
145. In a simple application which of the following parameters are inputs?
a) Pulse duration and current
b) Normal and abnormal pulses
c) All of the mentioned
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: Inputs used are pulse duration and current in a simple application.
146. In a simple application which of the following parameters are outputs?
a) Pulse duration and current
b) Normal and abnormal pulses
c) All of the mentioned
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: Outputs used are normal and abnormal pulses in a simple application.
147. Which of the following are correlated with the machining conditions at output stage?
a) Machining depth
b) Surface roughness
c) Accuracy
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Machining depth, surface roughness, accuracy are correlated with the machining conditions at the output stage.
Take Advanced Machining Processes Practice Tests – Chapterwise!
Start the Test Now: Chapter 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
148. How are EDM’s levels of integration when compared to conventional machining?
a) Slower rate
b) Faster rate
c) Same rate
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: EDM’s levels of computer integration is at a slower rate when compared to conventional machining processes.
149. Manufacturing of tool electrode undergoes which of the following processes?
a) Milling
b) Turning
c) Finishing
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: The tool electrode manufacturing used in EDM has to undergo the basic production processes such as milling, turning and finishing.
150. High temperatures produced in the working gap results in which of the following potentials?
a) Hazardous smoke
b) Toxic vapours
c) Aerosols
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: The temperatures in the working gap increases leading to hazardous smoke, vapours and aerosols.
151. Hydro carbons present in the dielectric fluid have impact on which of the body parts?
a) Eyes
b) Teeth
c) Skin
d) Nails
Answer & Explanations
Answer: c
Explanation: Hydrocarbons present in dielectric fluids of EDM will have a negative impact on the skin in our body.
152. What happens to the Electro discharge machining process under unfavourable working conditions?
a) Will remain stable
b) Explosion may occur
c) Machining rate increases
d) Nothing happens
Answer & Explanations
Answer: b
Explanation: Explosion occurs if Electro discharge machining is done under unfavourable process variables and conditions.
153. Reduction in the electrical energy consumption will have impact on which aspects mentioned below?
a) Environmental
b) Economic
c) Environmental & Economic
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: The reduction of electric energy consumption has economic as well as environmental benefits.
154. What fraction of tool will always be in contact with the work piece?
a) Half
b) Full
c) No contact
d) Quarter
Answer & Explanations
Answer: c
Explanation: Tool does not have any contact with the work piece in Electro chemical machining.
155. How much amount of wear is present in the tool used in Electrochemical machining?
a) No wear
b) Low
c) Medium
d) High
Answer & Explanations
Answer: a
Explanation: The tool wear is absent in the tool used in ECM, since tool has no contact with the work piece.
156. Compared to other processes, machining is done at __________ voltages for high rates of material removal.
a) Low
b) Medium
c) High
d) very low
Answer & Explanations
Answer: c
Explanation: In ECM, machining is done at low voltages, when compared to other processes.
157. Very small dimensions, up to which value can be controlled using ECM?
a) 0.01 mm
b) 0.05 mm
c) 0.07 mm
d) 0.12 mm
Answer & Explanations
Answer: b
Explanation: Due to less electrode gap very small dimensions up to 0.05 mm can be controlled.
158. Complicated profiles can be machined in how many operations in Electrochemical machining?
a) Single
b) Double
c) Triple
d) Multiple
Answer & Explanations
Answer: a
Explanation: One of the main advantage of ECM is, complicated profiles can be machined in a single operation itself.
Take Advanced Machining Processes Mock Tests – Chapterwise!
Start the Test Now: Chapter 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
159. How much amount of thermal damage occurs to the work piece?
a) Small
b) Large
c) No thermal damage
d) Negligible amount
Answer & Explanations
Answer: c
Explanation: As the temperatures are very low, no thermal damage occurs to the work piece material.
160. Which of the following materials can be machined using ECM?
a) Hard nonconductive materials
b) Hard conductive materials
c) All nonconductive materials
d) None of the mentioned
Answer & Explanations
Answer: b
Explanation: Hard conductive materials can be machined and nonconductive materials cannot be machined using ECM.
161. What are the requirements of labour for machining purpose in Electrochemical machining?
a) Low
b) Medium
c) High
d) Very high
Answer & Explanations
Answer: a
Explanation: In electrochemical machining, labour requirements are low compared to conventional or traditional machining practices.
162. How much amount of energy is consumed in Electro chemical machining?
a) Very small
b) Small
c) Medium
d) Large
Answer & Explanations
Answer: d
Explanation: Very huge amount of energy is required for ECM, which is nearly 100 times required for turning or drilling of steel.
163. How are material removal rates of ECM, when compared to that of conventional methods?
a) Slower
b) Faster
c) Same
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: In ECM, rates of material removal are slow compared to conventional methods.
164. State whether the following statement is true or false regarding the limitations of ECM.
“In ECM, cleaning and oiling of work piece need not be done after machining.”
a) True
b) False
Answer & Explanations
Answer: b
Explanation: Work piece needs to be cleaned and oiled just after the machining is done.
165. Which of the following are the limitations of electro chemical machining?
a) Removal of hydrogen
b) Handling the electrolyte
c) Energy consumption
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Removal of hydrogen, handling and containing the electrolyte and energy consumption are some of the limitations of ECM.
166. State whether the following statement is true or false regarding the limitations of ECM.
“In electrochemical machining, duplicating the tool is easier.”
a) True
b) False
Answer & Explanations
Answer: b
Explanation: Duplication of tool is difficult in ECM, since it has side machining effects.
167. Electro chemical machining process cannot produce which of the following mentioned below?
a) Drilled holes
b) Deburred edges
c) Sharp edges
d) All of the mentioned
Answer & Explanations
Answer: c
Explanation: Electro chemical machining cannot produce sharp internal or external edges.
168. Pumping of electrolyte through the narrow gaps causes, which type of forces on tool and work piece?
a) Large
b) Small
c) Negligible
d) No force
Answer & Explanations
Answer: a
Explanation: Electrolyte pumping through the narrow gaps gives rise to a large amount of forces on tool and work pieces.
169. If electro chemical machining is applied under appropriate conditions, how much amount of health dangers can occur?
a) Small amount
b) Limited amount
c) Large amount
d) Very large amount
Answer & Explanations
Answer: b
Explanation: Occupational health dangers are limited if ECM is done at appropriate conditions.
170. Which of the following are some of the bad impacts on environment while using ECM?
a) Electrolyte splashing
b) Toxic gases release
c) Precipitation of solid matters
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Electrolyte splashing, precipitation of solid matter, and toxic gas release is very harmful to the environment.
171. Which of the following parts of the body can be contaminated while using ECM?
a) Skin
b) Eyes
c) Skin & Eyes
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: Contamination of skin and eyes may occur due to electrolyte splashing and toxic gas release.
172. During deburring and die sinking which of the following electrolyte gives high surface quality and accuracy?
a) NaNO3
b) HNO3
c) NaCl
d) All of the mentioned
Answer & Explanations
Answer: a
Explanation: By using NaNO3, deburring and die sinking can be done with more accuracy and high qualities are obtained.
173. Dissolution of metal containing chrome results in which of the toxic compounds?
a) Toxic chromate
b) Ammonia
c) Toxic chromate & Ammonia
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: Dissolution of metal containing chromate results nitrate reduction at cathode tool, which in turn produces toxic chromate and ammonia.
174. Slurries mixing with toxic compounds produce, which of the following?
a) Solid precipitates
b) Liquid solutions
c) All of the mentioned
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: Slurries which mix with toxic compounds such as chromate and ammonia precipitates solid matter in the electrolyte solution.
175. What should be done to the electrolyte with solid matter?
a) Can be reused
b) Disposed off
c) No disposing is necessary
d) All of the mentioned
Answer & Explanations
Answer: b
Explanation: The electrolyte which contain the solid precipitates needs to be disposed immediately, in order to avoid any damage to the environment.
176. State whether the following statement is true or false regarding the environmental impacts of ECM.
“In ECM, accumulation of toxic compounds is due to nitrate reduction at tool cathode.”
a) True
b) False
Answer & Explanations
Answer: a
Explanation: When chromate containing metals dissolute, nitrate accumulate at cathode tool, which results in toxic chromate and ammonia compounds.
177. What is the full form of ECDR in advanced machining processes?
a) Electrochemical Dissolution
b) Electrochemical Drilling
c) Electrochemical Degradation
d) Electrochemical Devastation
Answer & Explanations
Answer: b
Explanation: In advanced machining processes, full form of ECDR is Electrochemical Drilling.
178. What are the values of diameters produced using Electrochemical drilling process?
a) 0.01 to 0.2 mm
b) 1 to 20 mm
c) 30 to 50 mm
d) 60 to 100 mm
Answer & Explanations
Answer: b
Explanation: Value of diameter produced using Electrochemical drilling, ranges between 1 to 20 mm.
179. What are the feed rates used in Electrochemical drilling?
a) 0.1 to 0.6 mm/min
b) 0.6 to 1 mm/min
c) 1 to 5 mm/min
d) 6 to 15 mm/min
Answer & Explanations
Answer: c
Explanation: Value of feed rates used in Electrochemical drilling, range between 1 to 5 mm/min.
180. Of the following, which type of electrodes is used as tool in ECDR?
a) Tubular electrodes
b) Flat electrodes
c) Cylindrical electrodes
d) All of the mentioned
Answer & Explanations
Answer: a
Explanation: In ECDR, tubular electrodes are used as cathodic tools for making holes in the materials.
181. The electrolyte is pumped the ________ of tool and exits through _________ of tool.
a) Centre, side
b) Side, centre
c) All of the mentioned
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: Usually, electrolyte is pumped from centre and exits from side machining gap and vice-versa can also be done in back pressure process.
182. Material is removed using which part of the electrode in ECDR?
a) Only front
b) Only side
c) Front and side
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: Material is removed at the frontal gaps and also dissolution takes place at the side machining gaps of the cathodic tool and work piece.
183. Overcut produced in ECRD is difference between which of the following parameters?
a) Diameter of tool, diameter of hole
b) Diameter of hole, diameter of tool
c) Depth of tool, diameter of tool
d) Diameter of tool, depth of tool
Answer & Explanations
Answer: b
Explanation: Overcut is the difference between the diameter of hole produced in work piece and the diameter of tool.
184. For high machining accuracy and smaller diametrical oversize, which type of feed rates are required?
a) Very low
b) Low
c) Medium
d) High
Answer & Explanations
Answer: d
Explanation: High feed rates are recommended for smaller diametrical oversize and more accuracy.
185. What happens to the overcut size, if we use the electrolyte flow mode under backward pressure?
a) Decreases
b) Increases
c) Increase and then decrease
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: If we use backward pressure for electrolyte flow, the overcut size decreases.
186. What are the values of pressure, used in backward pressure mode of electrolyte flow?
a) 0.01 to 0.12 MPa
b) 0.15 to 0.46 MPa
c) 0.6 to 2 MPa
d) 5 to 12 MPa
Answer & Explanations
Answer: c
Explanation: To reduce overcut size, reverse flow of electrolyte can be used under backward pressure mode, whose value ranges between 0.6 to 2 MPa.
187. What happens to the electrolyte conductivity if the gap increases, in ECDR?
a) Increases
b) Decreases
c) Remains same
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: In ECDR, as the gap increases, the electrical conductivity increases and the dissolution of material increases.
188. Electrolyte back pressure _________ the flow lines on work piece machined using ECDR.
a) Enhances
b) Eliminates
c) Maintains
d) Increases
Answer & Explanations
Answer: b
Explanation: Electrolyte back pressure eliminates the flow lines on the machined surfaces which is a major advantages of ECDR.
189. What happens to the roundness error if we use the rotation of ECDR tool?
a) Increases
b) Remains same
c) Decreases
d) Enhances
Answer & Explanations
Answer: c
Explanation: Roundness error decreases, if the tool is rotated in ECDR, since it ensures the homogenous flow of electrolyte in the machining gaps.
190. If sparking occurs due to very less gap between work surfaces, which parts gets damaged?
a) Tool
b) Work piece
c) All of the mentioned
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: Sparking, which occur due to very less gap between tool and work piece, which damages both the parts in ECDR.
191. Current efficiencies <100 percent may be related to, which of the following incidents?
a) Gas evolution
b) Passive oxide film formation
c) Less dissolution
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Current efficiencies less than 100 percent may be related to gas evolution, passive oxide formation, which in turn lead to less dissolution.
192. What is the full form of STEM in advanced machining processes?
a) Small Tool Electrode Machining
b) Small Tube Electrode Manufacturing
c) Shaped Tube Electrolytic Machining
d) Shaped Tube Electrode Machining
Answer & Explanations
Answer: c
Explanation: Full form of STEM in advanced machining processes is Shaped tube electrolytic machining.
193. Material is removed on which basis, in Shaped tube electrolytic machining?
a) Dissolution
b) Vaporization
c) Abrasion
d) Erosion
Answer & Explanations
Answer: a
Explanation: In STEM, dissolution takes place when a potential difference is applied between the anodic work piece and cathodic tool.
194. Which of the following can be used as electrolytes in STEM process?
a) Sulphuric acid
b) Nitric acid
c) Hydrochloric acids
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Electrolytes used in STEM are sulphuric acid, nitric acid and hydrochloric acids.
195. What is the percentage of electrolyte dissolved in water?
a) 1 – 5%
b) 10 – 25%
c) 40 – 70%
d) 75 – 90%
Answer & Explanations
Answer: b
Explanation: Concentration of electrolyte, used in STEM, is 10 – 25% weight in water.
196. What may be the temperature of sulphuric acid used in the STEM process?
a) 10 oC
b) 21 oC
c) 38 oC
d) 50 oC
Answer & Explanations
Answer: c
Explanation: The temperature of sulphuric acids used in the STEM process may be around 38 oC.
Get Free Certificate of Merit in Advanced Machining Processes Now!
197. What may be the temperatures of acids used, other than sulphuric acid, in STEM?
a) 10 oC
b) 21 oC
c) 38 oC
d) 50 oC
Answer & Explanations
Answer: b
Explanation: Temperature of acids used in STEM, other than sulphuric acid, is about 21 oC.
198. What are the values of pressures used for electrolyte in STEM?
a) 10 – 100 kPa
b) 150 – 250 kPa
c) 275 – 500 kPa
d) 600 – 750 kPa
Answer & Explanations
Answer: c
Explanation: Values of pressure used in the STEM process, range between 275 – 500 kPa.
199. What are the voltage values used in the STEM process?
a) 1 – 4 V
b) 8 – 14 V
c) 16 – 24 V
d) 28 – 34 V
Answer & Explanations
Answer: b
Explanation: In STEM, voltage values used for the process to carry on, range between 8 – 14 V.
200. Compared to the forward voltages, how are the reverse voltages?
a) 0.01 – 0.1 times
b) 0.1 – 1 times
c) 1 – 10 times
d) 10 – 100 times
Answer & Explanations
Answer: b
Explanation: Reverse voltages used in STEM are 0.1 – 1 times the forward voltages, used in STEM.
201. Which of the following values, does the feed rate range between?
a) 0.01 – 0.1 mm/min
b) 0.25 – 0.5 mm/min
c) 0.75 – 3 mm/min
d) 5 – 7.5 mm/min
Answer & Explanations
Answer: c
Explanation: Feed rates used in STEM, range between 0.75 – 3 mm/min.
202. What may the hole sizes, that can be machined using STEM process?
a) 0.02 – 0.3 mm
b) 0.5 – 6 mm
c) 8 – 20 mm
d) 50 – 76 mm
Answer & Explanations
Answer: b
Explanation: The hole sizes that can be machined using STEM process, range between 0.5 – 6 mm.
203. What are the tolerance values for a 1.5 mm diameter hole, which is machined using STEM?
a) ± 0.025 mm
b) ± 0.050 mm
c) ± 0.075 mm
d) ± 0.100 mm
Answer & Explanations
Answer: c
Explanation: Diametrical tolerance value increases with the increase in hole diameter, which varies as – ± 0.050 mm for 0.6 mm diameter hole, ± 0.075 mm for 1.5 mm diameter hole and ± 0.100 mm for 6 mm hole diameter.
204. Which of the following parts can be machined using STEM process?
a) Turbine blade cooling nozzles
b) Fuel nozzles
c) Starting holes for wire-EDM
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: STEM has its applications in jet engines and gas turbine parts such as cooling nozzles for turbine blades, fuel nozzles and any holes where EDM recast is undesirable.
205. Which of the following are the advantages of STEM?
a) Depth to diameter ratio of 300
b) Non parallel holes can be drilled
c) No recast layer
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Main advantages of STEM are depth to diameter ratio of 300, non-parallel holes can be drilled, no recast layer are produced, shaped and curved holes can be produced.
206. What are the limitations of STEM process?
a) Used for corrosion resistant materials
b) Hazardous waste is generated
c) Complex machining and tooling systems
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Some of the limitations of STEM are only used for corrosion resistant materials, hazardous wastes are generated, special work place environment are required, complex machining and tooling systems are required.
207. In advanced machining processes, what is the full form of ES drilling?
a) Electro stream
b) Electrical shaped
c) Electron shaped
d) Electric shock
Answer & Explanations
Answer: a
Explanation: In advanced machining processes, full form of ES drilling is Electrostream drilling.
208. This Electrostream drilling is used when we cannot drill which of the following type of holes?
a) Too deep holes by EDM
b) Small holes by STEM
c) All of the mentioned
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: ES drilling is used to drill finer holes which are too deep to be produced by EDM and too small to be drilled by STEM.
209. What is the value of diameter of glass nozzle used in Electrostream drilling?
a) 0.01 – 0.02 mm
b) 0.025 – 0.5 mm
c) 0.5 – 0.75 mm
d) 0.75 – 1.25 mm
Answer & Explanations
Answer: b
Explanation: Electrostream drilling uses a gas nozzle, whose diameter ranges between 0.025 – 0.5 mm.
210. Compared to the required diameter of the hole, how is the nozzle diameter?
a) Smaller
b) Larger
c) Same as required
d) All of the mentioned
Answer & Explanations
Answer: a
Explanation: The diameter of nozzle used is smaller than the hole size required to be drilled in work piece.
211. Which of the following acts as the cathodic tool in ES drilling?
a) Titanium base
b) Platinum wire
c) Glass nozzle
d) Work piece
Answer & Explanations
Answer: b
Explanation: Unlike the case of STEM process, which uses coated Ti tube as cathode, ES drilling used platinum wire as cathode electrode.
Take Advanced Machining Processes Tests Now!
212. What is the concentration of electrolytes that are commonly used in ES drilling?
a) 1 to 10wt %
b) 12 to 20wt %
c) 23 to 30wt %
d) 34 to 50wt %
Answer & Explanations
Answer: b
Explanation: Commonly used electrolytes have a concentration between 12 to 20wt %.
213. State whether the following statement is true or false regarding ES drilling.
“In ES drilling, hydrochloric acid is used for machining aluminium and its alloys.”
a) True
b) False
Answer & Explanations
Answer: a
Explanation: Hydrochloric acids are used for machining Al and its alloys and sulphuric acid is recommended for other metals.
214. Which of the following are the metals, which can be machined using sulphuric acid?
a) Carbon steels
b) Haste alloy
c) Inconel
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Haste alloy, Rene alloy, Inconel, carbon and stainless steels are the materials machined using sulphuric acid.
215. What are the values of electrolyte pressure recommended for ES drilling?
a) 50 – 100 kPa
b) 100 – 250 kPa
c) 275 – 400 kPa
d) 500 – 750 kPa
Answer & Explanations
Answer: c
Explanation: Electrolyte pressure values must range between 275 – 400 kPa for ES drilling to take place.
216. Which of the following parameters must be carefully monitored for satisfactory machining?
a) Acid temperature
b) Pressure
c) Concentration
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Acid temperature, pressure, concentration and feed rate are to be carefully monitored for satisfactory machining.
217. What are the values of voltages used in ES drilling process?
a) 10 to 40 V
b) 40 to 70 V
c) 70 to 150 V
d) 150 to 300 V
Answer & Explanations
Answer: c
Explanation: Voltage values used in ES drilling, range between 70 to 150 V.
218. What are the values of feed rates used in ES drilling process?
a) 0.01 to 0.5 mm/min
b) 0.75 to 2.5 mm/min
c) 3 to 4.5 mm/min
d) 5 to 7.5 mm/min
Answer & Explanations
Answer: b
Explanation: Feed rate values used in ES drilling, range between 0.75 to 2.5 mm/min.
219. Higher material removal rates are associated with _________ feed rates and _________ tool diameters.
a) Larger, smaller
b) Smaller, larger
c) Smaller, smaller
d) Larger, larger
Answer & Explanations
Answer: d
Explanation: Rates of material removal are high, when feed rates are high and larger tool diameters.
220. What are the normal hole depth tolerance values in ES drilling?
a) ± 0.03 mm
b) ± 0.05 mm
c) ± 0.07 mm
d) ± 0.09 mm
Answer & Explanations
Answer: b
Explanation: The normal hole depth tolerances obtained in ES drilling, range between ± 0.05 mm.
221. How many holes can be drilled simultaneously using ES drilling process?
a) One hole
b) Two holes
c) Three holes
d) Multiple holes
Answer & Explanations
Answer: d
Explanation: Depending upon the size of diameters, multiple holes can be drilled using ES drilling.
222. In advanced machining processes, what is the full form of ECJD?
a) Electrochemical Jet Dimensioning
b) Electrochemical Jet Drilling
c) Electrical Jet Drilling
d) Electrical Jet Dimensioning
Answer & Explanations
Answer: b
Explanation: In advanced machining processes, full form of ECJD is Electrochemical Jet Drilling.
223. What is the value of diameter-to-depth ratio obtained using ECJD process?
a) 1:10
b) 2:25
c) 1:12
d) 1:100
Answer & Explanations
Answer: c
Explanation: Electrochemical jet drilling is the process used for producing fine holes, having diameter to depth ratio of 1:12.
224. Compared to the diameter to depth ratio of ES drilling, how is ECJD’s ratio?
a) Lower
b) Higher
c) Same as ES
d) None of the mentioned
Answer & Explanations
Answer: a
Explanation: ES drilling has a diameter to depth ratio of 1:100, while ECJD has a ratio of 1:12.
225. How is the material removed in Electrochemical jet drilling process?
a) Using Platinum wire
b) Using Ti coated electrode
c) By spraying electrolyte
d) Using glass nozzle
Answer & Explanations
Answer: c
Explanation: Material is removed by spraying electrolyte through the cathode, in Electrochemical jet drilling.
226. What is the material removal mechanism used in Electrochemical jet drilling?
a) Abrasion
b) Dissolution
c) Vaporization
d) Erosion
Answer & Explanations
Answer: b
Explanation: Electrochemical dissolution is the means of material removal in Electrochemical jet drilling.
227. What are the values of voltages used in Electrochemical jet drilling process?
a) 100 to 200 V
b) 200 to 400 V
c) 400 to 800 V
d) 800 to 1600 V
Answer & Explanations
Answer: c
Explanation: The optimum range of voltages used in Electrochemical jet drilling are between 400 to 800 V.
228. The lower limit of the hole size in ECJD, is determined by which of the following factors?
a) Smallest hole
b) Pressure required
c) Amount of overcut
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: The lower limit of hole size depend on smallest hole that can be drilled in cathodic nozzle, pressure required for pumping electrolyte and the overcut amount.
229. State whether the following statement is true or false regarding ECJD.
“In ECJD, diameter of hole produced, depend up on the throwing power of electrolyte.”
a) True
b) False
Answer & Explanations
Answer: a
Explanation: Diameter of the hole produced, depend up on the throwing power of electrolyte.
230. Compared to the diameter of the electrolyte jet, how are the produced hole diameters?
a) 2 times
b) 3 times
c) 4 times
d) 5 times
Answer & Explanations
Answer: c
Explanation: In ECJD, the holes produced are nearly 4 times that of the electrolyte jet diameter used in the process.
231. What is the value of the ratio of hole diameter to capillary diameter in ECJD?
a) 2
b) 4
c) 6
d) 8
Answer & Explanations
Answer: a
Explanation: Generally, ratio of hole diameter to capillary diameter in ECJD is 2.
232. What are the values of tapers produced in Electrochemical jet drilling process?
a) 1 to 2 included angles
b) 5 to 10 included angles
c) 10 to 15 included angles
d) 20 to 30 included angles
Answer & Explanations
Answer: b
Explanation: In Electrochemical jet drilling tapers produced are about 5 to 10 included angles.
233. State whether the following statement is true or false regarding ECJD?
“In ECJD, there is no need of room for exit of electrolyte.”
a) True
b) False
Answer & Explanations
Answer: b
Explanation: In ECJD, enough room is required for the exit of electrolyte, preferably in the form of spray.
234. How much part of tool needs to be in contact with work piece for removal of material?
a) Quarter
b) Half
c) Full
d) No contact
Answer & Explanations
Answer: d
Explanation: As this is an electrochemical dissolution process, electrodes should not be in contact in order to avoid sparking.
235. In advanced machining processes, full form of ECDB is _________
a) Electrochemical Drill buffing
b) Electrochemical Dimension Breaking
c) Electrochemical Deburring
d) Electrochemical Dimensioning
Answer & Explanations
Answer: c
Explanation: In advanced machining processes, full form of ECDB is Electrochemical Deburring.
236. Which of the following processes can be used for deburring?
a) Water blasting
b) Abrasive flow machining
c) Electrochemical deburring
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Different methods used for deburring include vibratory and barrel finishing, tumbling, water blasting, Abrasive flow machining, Electrochemical deburring and many more.
237. In the following electrodes, on which one the process of deburring takes place?
a) Cathode
b) Anode
c) Cathode & Anode
d) None of the mentioned
Answer & Explanations
Answer: c
Explanation: Anode is the electrode, on which, the process of deburring is done.
238. Burrs are removed at which amount of current densities below?
a) Very low
b) Low
c) High
d) Medium
Answer & Explanations
Answer: c
Explanation: High current densities are required to remove the burrs from the work pieces.
239. After deburring is done, which of the following is formed?
a) Flat surfaces
b) Controlled radius
c) Sharp edges
d) All of the mentioned
Answer & Explanations
Answer: b
Explanation: Dimensions of the part are changes by the removal of burrs leaving a controlled radius.
Become Top Ranker in Advanced Machining Processes Now!
240. To which components mentioned below, ECDM can be applied?
a) Spline shafts
b) Milled components
c) Drilled holes
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: ECDB can be applied to gears, spline shafts, milled components, drilled holes, and punched blanks.
241. What are the values of deburring speeds used in ECDB process?
a) 100 to 200 mm/min
b) 200 to 400 mm/min
c) 400 to 500 mm/min
d) 500 to 700 mm/min
Answer & Explanations
Answer: c
Explanation: Values of speeds of deburring, range between 400 to 500 mm/min.
242. What are the normal cycle times for deburring process using ECDB?
a) 10 to 20 s
b) 30 to 45 s
c) 50 to 70 s
d) 80 to 100 s
Answer & Explanations
Answer: b
Explanation: The normal cycle times are between 30 to 45 s after which, spindle is retracted and part is removed.
243. What is the value of burr height that can be removed using ECDB process?
a) 0.1 mm
b) 0.3 mm
c) 0.5 mm
d) 0.7 mm
Answer & Explanations
Answer: c
Explanation: Burr height of around 0.5 mm can be removed using ECDB process.
244. Burr is removed to a radius of _________ in ECDB process.
a) 0.01 to 0.04 mm
b) 0.05 to 0.20 mm
c) 0.25 to 0.40 mm
d) 0.50 to 0.75 mm
Answer & Explanations
Answer: b
Explanation: Burr of height 0.5 mm to a radius of 0.05 to 0.2 mm can be removed using ECDB.
245. What is the value of surface roughness obtained in Electrochemical deburring process?
a) 0.1 to 1 µm
b) 1 to 2 µm
c) 2 to 4 µm
d) 5 to 8 µm
Answer & Explanations
Answer: c
Explanation: Surface roughness obtained in ECDB process is about 2 to 4 µm.
246. What is the value of pressure of electrolyte used in ECDB process?
a) 0.1 to 0.2 MPa
b) 0.3 to 0.5 MPa
c) 0.7 to 0.9 MPa
d) 1.1 to 1.5 MPa
Answer & Explanations
Answer: b
Explanation: Pressure of electrolyte used in ECDB is maintained between 0.3 to 0.5 MPa.
247. What is the value of applied voltage used in ECDB process?
a) 1 to 5 V
b) 5 to 11 V
c) 12 to 24 V
d) 25 to 50 V
Answer & Explanations
Answer: c
Explanation: Value of voltage used in ECDB process ranges from 12 to 24 V.
248. What are the values of current densities used in ECDB process?
a) 1 – 5 A/cm2
b) 5 – 10 A/cm2
c) 10 – 15 A/cm2
d) 15 – 20 A/cm2
Answer & Explanations
Answer: b
Explanation: Current densities used in ECDB process range between 5 – 10 A/cm2.
249. Which of the following electrolyte can be used for deburring process in ECDB?
a) NaNO2
b) NaNO3
c) NaCl
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Sodium nitrite, sodium nitrate and sodium chloride are the electrolytes used in ECDB process.
250. What are the values, of inter electrode gaps so that machining occurs easily?
a) 0.01 to 0.1 mm
b) 0.1 to 0.3 mm
c) 0.3 to 0.5 mm
d) 0.5 to 0.7 mm
Answer & Explanations
Answer: c
Explanation: The inter electrode gap maintained in ECDB process, range between 0.30 – 0.50 mm.
252. In order to produce a proper radius, by how much should the tool tip overlap the machined area?
a) 0.5 to 1 mm
b) 1 to 1.5 mm
c) 1.5 to 2 mm
d) 2 to 2.5 mm
Answer & Explanations
Answer: b
Explanation: In ECDB, the tool tip should overlap the machined area by 1.5 to 2 mm in order to produce a proper radius.
253. Which of the following materials can be machined using ECDB process?
a) Carbon steels
b) Copper alloys
c) Aluminium alloys
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: All the materials mentioned above, can be machined using ECDB process.
254. In ECDB process, rotating and feeding the tool electrode __________ the deburring process.
a) Enhances
b) Degrades
c) Damages
d) All of the mentioned
Answer & Explanations
Answer: a
Explanation: Rotating and feeding the tool in ECDB process, enhances the process of deburring.
255. Electrochemical deburring ensures which of the following factors after removal of burrs?
a) Required accuracy
b) Proper radius
c) Clean edge
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: ECDB ensures the removal of burrs art required accuracy, uniformity, proper radius and clean edges.
256. Which of the following are the advantages of using ECDB process?
a) Increased product quality
b) Reduced labour cost
c) Increased reliability
d) All of the mentioned
Answer & Explanations
Answer: d
Explanation: Increased product quality and reliability, reduced labour costs, elimination of costly hand deburring etc.., are some of the advantages of ECDB.
257. State whether the following statement is true or false regarding the advantages of ECDB.
“In ECDB, automation does not contribute to productivity.”
a) True
b) False
Answer & Explanations
Answer: b
Explanation: Electrochemical deburring can be automated for higher productivity.
