Electrochemical Processes
1. In advanced machining processes, what is the full form of ECM?
a) Electrochemical manufacturing
b) Electrochemical milling
c) Electrochemical machining
d) Electrochemical masking
.
Answer: b
Explanation: In advanced machining processes, the full form of ECM is Electrochemical machining.
2. In the following scientists, who was the one to introduce first patent on ECM?
a) Balamuth
b) Steve O Flawer
c) Gusseff
d) McGeough
.
Answer: c
Explanation: Gusseff was the one, who introduced the first patent on ECM in 1929.
3. When was the first significant development of ECM occurred?
a) 1920s
b) 1930s
c) 1950s
d) 1960s
.
Answer: c
Explanation: After the first patent in 1929, the first development of ECM was done in 1950s.
4. Which of the following material removal mechanisms is implemented by ECM?
a) Mechanical abrasion
b) Electrochemical dissolution
c) Chemical corrosion
d) Mechanical erosion
.
Answer: b
Explanation: In ECM, material is removed by electrochemical dissolution.
5. Electrolysis occur when which of the following takes place between electrodes?
a) Electric current flow
b) Electron flow
c) All of the mentioned
d) None of the mentioned
.
Answer: c
Explanation: When there is an electron flow there is current flow in the opposite direction. For electrolysis to take place there should be flow of current between electrodes.
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6. The system which consists of electrolytic solution and electrodes can be referred to as ____________
a) Electrolytic cell
b) Electrode system
c) Electrolytic system
d) Electrode cell
.
Answer: a
Explanation: The system of electrodes and electrolytic solution is referred as electrolytic cell.
7. The chemical reactions occurring at electrodes are called with, which of the following names?
a) Anodic reactions
b) Cathode reactions
c) All of the mentioned
d) None of the mentioned
.
Answer: c
Explanation: Chemical reactions occurring at electrodes are called as anodic or cathodic reactions.
8. Amount of mass dissolved is directly proportional to which of the following quantities?
a) Amount of electricity
b) Frequency of vibrations
c) Amplitude of oscillations
d) All of the mentioned
.
Answer: a
Explanation: Amount of mass dissolved is directly proportional to amount of electricity and also substances’ chemical equivalent.
9. Chemical equivalent is the ratio of which of the following factors?
a) Work piece valence to the atomic weight
b) Atomic weight to work piece valence
c) Tool valence to molecular weight
d) Molecular weight to tool valence
.
Answer: b
Explanation: Chemical equivalent is the ratio of atomic weight to work piece valence.
10. What is the value of the current density used in Electrochemical machining?
a) 0.01 – 0.4 A/mm2
b) 0.5 – 5 A/mm2
c) 6 – 15 A/mm2
d) 20 – 50 A/mm2
.
Answer: b
Explanation: High current densities, which range between 0.5 – 5 A/mm2 are used in ECM.
11. What are the values of voltages used in ECM?
a) 1 to 8 V
b) 10 to 30 V
c) 40 to 80 V
d) 90 to 110 V
.
Answer: b
Explanation: Low voltages, ranging between 10 to 30 V are used in Electrochemical machining.
12. How does the current pass between the two electrodes in ECM?
a) Electrolytic solution
b) Direct contact of electrodes
c) All of the mentioned
d) None of the mentioned
.
Answer: a
Explanation: Current passes through the solution of electrolyte, which fills the gap between the electrodes.
13. What is the value of velocity with which, electrolyte flows in the inter electrode gap?
a) >1 m/s
b) >3 m/s
c) >5 m/s
d) >10 m/s
.
Answer: c
Explanation: The velocity of the electrolytic solution must be greater than 5 m/s, in order to intensify the mass and charge transfer.
14. Of the following, electrolyte removes which of the dissolution products?
a) Metal hydroxides
b) Heat
c) Gas bubbles
d) All of the mentioned
.
Answer: d
Explanation: Electrolyte removes the dissolution products such as metal hydroxides, heat and gas bubbles formed in the inter electrode gap.
15. State whether the following statement is true or false regarding the theory of ECM.
“Application of P.D (potential difference) lead to occurrence of several reactions.”
a) True
b) False
.
Answer: a
Explanation: When P.D (potential difference) is applied, different reactions occur at anode and cathode.
16. Which of the following reactions takes place at the electrodes?
a) Generation of hydrogen
b) Dissolution of iron
c) Dissolution of NaCl
d) All of the mentioned
.
Answer: d
Explanation: All the reactions mentioned above, take place at different electrodes in ECM.
17. Which of the following reaction takes place at anode?
a) Generation of hydrogen
b) Dissolution of iron
c) Generation of hydroxyl ions
d) None of the mentioned
.
Answer: b
Explanation: At anode, dissolution of Fe takes place in the process of ECM.
18. Which of the following reactions take place at cathode?
a) Generation of hydrogen
b) Dissolution of iron
c) Dissolution of NaCl
d) All of the mentioned
.
Answer: a
Explanation: At cathode, generation of hydrogen takes place in the process of ECM.
19. Positively charged particles (cations) move towards which electrode?
a) Anode
b) Cathode
c) Anode & Cathode
d) None of the mentioned
.
Answer: b
Explanation: Positively charge particles are directed towards the cathode, which is negatively charged.
20. Negatively charged particles (anions) move towards which electrode?
a) Anode
b) Cathode
c) Anode & Cathode
d) None of the mentioned
.
Answer: a
Explanation: Negatively charged particles are directed towards the anode, which is positively charged.
21. Which of the following come under the main components of ECM?
a) Feed control system
b) Work piece holding devices
c) Electrolyte supply system
d) All of the mentioned
.
Answer: d
Explanation: The main components of Electro chemical machining include feed control system, electrolyte supply system, power supply unit, work piece holding devices.
22. Feed control system is responsible for which action in ECM?
a) Giving feed to tool
b) Electrolyte supply
c) Power supply
d) None of the mentioned
.
Answer: a
Explanation: Feed control system is used for feeding the tool at constant rate during equilibrium machining.
23. In ECM equipment, what is the role of electrolyte supply system?
a) Giving feed to tool
b) Electrolyte supply
c) Power supply
d) None of the mentioned
.
Answer: b
Explanation: As the name itself indicates, electrolyte supply system is used to supply the electrolyte required for anodic dissolution.
24. What is the role of power supply unit in ECM equipment?
a) Giving feed to tool
b) Electrolyte supply
c) Power supply
d) None of the mentioned
.
Answer: c
Explanation: In ECM, power supply unit is used to supply the machine current at constant dc voltage.
25. For large size machining, which type of facilities are used in ECM?
a) Semi-automated facilities
b) Automated facilities
c) Automated & Semi-automated facilities
d) None of the mentioned
.
Answer: c
Explanation: Automated and semi-automated facilities are used for large size machining.
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26. Electrolyte supply system should concentrate on which of the following factors?
a) Pressure
b) Supply rate
c) Temperature
d) All of the mentioned
.
Answer: d
Explanation: Electrolyte supply system should supply electrolyte at a given rate, temperature and pressure.
27. For high strength or rigidity, which type of coatings are recommended for metals?
a) Other metal coatings
b) Non-metallic coatings
c) All of the mentioned
d) None of the mentioned
.
Answer: b
Explanation: For high strength and rigidity, non-metallic coatings are recommended for metals.
28. What is the value of voltage that the power supply unit supplies for ECM?
a) 0.01 to 1 V
b) 2 to 30 V
c) 50 to 80 V
d) 100 to 160 V
.
Answer: b
Explanation: Voltage supply required for ECM ranges between 2 to 30 V.
29. Between which of the following values, does the current range?
a) 0.002 to 0.01 A
b) 0.01 to 10 A
c) 50 to 10000 A
d) 105 to 106 A
.
Answer: c
Explanation: In Electrochemical machining, current value ranges between 50 to 10000 A.
30. What are the values of current densities used in ECM?
a) 0.1 to 2 A/cm2
b) 5 to 500 A/cm2
c) 600 to 1000 A/cm2
d) 1200 to 2800 A/cm2
.
Answer: b
Explanation: Current density values in ECM range between 5 to 500 A/cm2.
31. Which type of adjustment is to be done for gap voltages?
a) Continuous adjustment
b) Discontinuous adjustment
c) Periodic adjustment
d) All of the mentioned
.
Answer: a
Explanation: In ECM, usually continuous adjustment of gap voltage is required.
32. Compared to the tool used in ECM, how should be the work piece size?
a) Greater than
b) Smaller than
c) Same as tool
d) None of the mentioned
.
Answer: a
Explanation: By an oversize, work piece size is expected to be greater than tool size.
33. Which of the following factors are used to determine the tool geometry?
a) Required shape
b) Electrical conductivity
c) Tool feed rate
d) All of the mentioned
.
Answer: d
Explanation: For determining a tool geometry we must specify some factors such as the required shape of the surface, tool feed rate, gap voltage, electrochemical machinability of the work material, electrolyte conductivity, and both electrodes’ polarization voltages.
34. Which of the following are the simplest methods for applying the insulation on tools?
a) Spraying
b) Dipping
c) All of the mentioned
d) None of the mentioned
.
Answer: c
Explanation: In ECM, dipping or spraying are the simplest methods for insulating the tools.
35. State whether the following statement is true or false regarding the tools of ECM.
“With computer integrated manufacturing (CIM), cathodes are produced at high costs and less accurately.”
a) True
b) False
.
Answer: b
Explanation: Using CIM, cathodes are produced at low costs and more accurately.
36. What are the main functions of electrolyte in Electrochemical machining?
a) Conduct machining current
b) Removal of debris
c) Maintaining constant temperature
d) All of the mentioned
.
Answer: d
Explanation: Main functions of electrolyte are conducting machine current, removing the debris, carrying away the heat, maintaining constant temperature.
37. Electrolytic solution should ensure which type of anodic dissolution?
a) Uniform
b) Non-uniform
c) Low speed
d) None of the mentioned
.
Answer: a
Explanation: Uniform and high speed anodic dissolution must be ensured by the electrolyte.
38. State whether the following statement is true or false regarding the electrolytic solution.
“In ECM, formation of passive film is recommended.”
a) True
b) False
.
Answer: b
Explanation: Electrolytic solution should avoid formation of passive layers on anode.
39. Which type of electrical conductivity is necessary for electrolytic solution?
a) Low
b) Medium
c) High
d) None of the mentioned
.
Answer: c
Explanation: High electrical conductivity is needed for electrolytic solution in ECM.
40. What are the other features of electrolytic solution in ECM?
a) Non toxic
b) Less erosive
c) Less viscous
d) All of the mentioned
.
Answer: d
Explanation: Electrolytic solution should be nontoxic, less viscous and less erosive.
41. How much should be the electrolytic solution?
a) Highly expensive
b) Inexpensive
c) All of the mentioned
d) None of the mentioned
.
Answer: b
Explanation: Electrolyte must be inexpensive and available at ease.
42. Which are the most common electrolytes used in Electrochemical machining?
a) Sodium chloride
b) Sodium nitride
c) Sodium hydroxide
d) All of the mentioned
.
Answer: d
Explanation: Electrolytes such as sodium chloride, sodium nitride, sodium hydroxide are some of the electrolytes used in ECM.
43. Selection of electrolyte does not depend on which of the following factors?
a) Work piece material
b) Dimensional tolerance
c) Heat affected zones
d) Machining productivity
.
Answer: c
Explanation: Selection of electrolyte depend up on work piece material, dimensional tolerance, machining productivity and surface finish required.
44. What must be the value of electrolytic temperature in ECM?
a) 2 to 14oC
b) 22 to 45oC
c) 46 to 57oC
d) 62 to 76oC
.
Answer: b
Explanation: Temperature of electrolyte should range between 22 to 45oC.
45. What must be the value of the pressure of electrolytic solution used in ECM?
a) 1 to 10 kPa
b) 10 to 80 kPa
c) 100 to 200 kPa
d) 300 to 400 kPa
.
Answer: c
Explanation: Value of pressure of electrolytic solution must range between 100 to 200 kPa.
46. What must be the value of velocity of the electrolytic solution?
a) 10 to 15 m/s
b) 25 to 50 m/s
c) 60 to 100 m/s
d) 120 to 200 m/s
.
Answer: b
Explanation: Typical velocity of the electrolytic solution must range between 25 to 50 m/sec.
47. Local metal removal rates are high at which gap locations mentioned below?
a) Small gap
b) Medium gap
c) Large gap
d) None of the mentioned
.
Answer: a
Explanation: Local metal removal rates are high at small gap locations in ECM.
48. When local metal removal rates are high, how will be the current density and current efficiency?
a) High
b) Medium
c) Low
d) Very low
.
Answer: a
Explanation: When the local metal removal rates are high then current density and efficiency are also high.
49. Current efficiency depends on which of the following in ECM?
a) Anodic material
b) Electrolyte
c) Anodic material & Electrolyte
d) None of the mentioned
.
Answer: c
Explanation: Current efficiency in ECM depend on electrolyte and anodic material used.
50. State whether the following statement is true or false regarding the electrolytes in ECM.
“In Electrochemical machining, electrolytes should deposit on cathode electrodes.”
a) True
b) False
.
Answer: b
Explanation: In ECM, electrolytes should not deposit on cathode, so that shape of electrode remains unchanged.
51. What is the approximate value of faraday’s constant?
a) 65,200 C
b) 53,800 C
c) 96,500 C
d) 85,600 C
.
Answer: c
Explanation: 1 faraday equals to approximately 96500 C.
52. In the following ratios of metal dissolved amounts, which one represent the current efficiency?
a) Observed to theoretical
b) Theoretical to observed
c) All of the mentioned
d) None of the mentioned
.
Answer: a
Explanation: In electrochemical machining, current efficiency is the ratio of observed amount of metal dissolved to the theoretical amount of metal dissolved.
53. Apparent current efficiency is due to which of the following factors?
a) Choice of wrong valence
b) Passivation of anodic surface
c) Gas evolution at anode
d) All of the mentioned
.
Answer: d
Explanation: Current efficiency may be apparent because of choice of wrong valence, passivation of anodic surface or gas evolution at anodic surface.
54. State whether the following statement is true or false regarding the working principles.
“In ECM, grain boundary attacks remove the grains through electrolytic forces.”
a) True
b) False
.
Answer: a
Explanation: In ECM, grain boundary attacks are the cause for removal of grains by electrolytic forces.
55. In ECM, gap increase proportional to which relation of time below?
a) Square of time
b) Square root of time
c) Cube of time
d) Cube root of time
.
Answer: b
Explanation: In Electrochemical machining, gap increases proportional to the square root of time.
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56. At constant feed rates what happens to gap thickness?
a) Increases
b) Decreases
c) Becomes constant
d) None of the mentioned
.
Answer: c
Explanation: At constant feed rate, work piece becomes stationary and thus the gap thickness becomes constant.
57. At constant gap thickness material removal becomes equal to feed rate. What is this gap called?
a) Equal gap
b) Equilibrium gap
c) Unique gap
d) Narrow gap
.
Answer: b
Explanation: When rate of material removal per unit area is same as feed rate, then corresponding thickness is called as equilibrium thickness indicated by ‘ye’.
58. If the gap thickness is greater than equilibrium thickness what will be MRR?
a) MRR is less than feed rate
b) MRR is greater than feed rate
c) MRR is equal to feed rate
d) None of the mentioned
.
Answer: a
Explanation: When gap thickness is greater than equilibrium thickness, MRR will be less than feed rate.
59. During ECM drilling, decrease in feed rates lead to which type of machining gaps?
a) Wider
b) Narrow
c) Small
d) None of the mentioned
.
Answer: a
Explanation: Decrease in feed rate lead to wider gap thickness in ECM drilling.
60. Too small gap causes which of the following effects?
a) Sparking
b) Short circuit
c) Sparking & Short circuit
d) None of the mentioned
.
Answer: c
Explanation: Sparking or short circuit occurs when the gap is too small.
61. Electro chemical dissolution phase starts with the movement of ions between which two components?
a) Cathode and anode
b) Cathode and power source
c) Power source and anode
d) Power source and electrolyte
.
Answer: a
Explanation: ECD phase occurs by the movement of ions between the two electrodes.
62. Better surface finish and higher accuracy depend on which of the factors below?
a) Chemical composition of the electrolyte
b) Current density
c) All of the mentioned
d) None of the mentioned
.
Answer: c
Explanation: Proper chemical composition of electrolyte and proper current density are responsible for better surface finish and accuracy.
63. For alloys, which type of electrolyte is used in ECM?
a) Single component
b) Double component
c) Multi component
d) Triple component
.
Answer: c
Explanation: Depending up on the elements in an alloy multi component electrolytes are used.
64. Nickel can be machined with 100% current efficiency, when current density value is ______________
a) 10 A/cm2
b) 25 A/cm2
c) 45 A/cm2
d) 80 A/cm2
.
Answer: b
Explanation: Nickel is a metal suggested by Khayry, which can be machined at 100% current efficiency, if current density is 25 A/cm2.
65. When the electrolyte flow is low, what happens to the current efficiency?
a) Increases
b) Decreases
c) Remains same
d) Increase and then decrease
.
Answer: b
Explanation: In ECM, if the electrolyte flow is low, current efficiency is reduced due to the accumulation of machining products within the gap.
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66. When machining Ti, in Nacl electrolyte, what values of current efficiencies are obtained?
a) 10 – 20 %
b) 20 – 30 %
c) 30 – 50 %
d) 50 – 80 %
.
Answer: a
Explanation: While machining Ti using NaCl electrolyte, current efficiencies of 10 – 20 percent are obtained.
67. State whether the following statement is true or false about electrolyte in ECM.
“Machinability in ECM is enhanced, when electrolyte is heated.”
a) True
b) False
.
Answer: a
Explanation: Machinability is increased, when electrolyte is heated, as heating increases the specific conductivity of the electrolyte.
68. In practice, what must be the temperature of electrolyte used in ECM?
a) 10 – 20oC
b) 20 – 40oC
c) 60 – 80oC
d) 80 – 100oC
.
Answer: c
Explanation: Temperature of electrolyte used in ECM must not exceed 60 – 70oC.
69. What is the value of moderate level of pH of electrolyte used?
a) 1 – 2
b) 2 – 4
c) 4 – 10
d) All of the mentioned
.
Answer: c
Explanation: Moderate level of pH of electrolyte used in ECM range between 4 – 10.
70. What must be the working voltage in Electrochemical machining?
a) 10 V
b) 20 V
c) 30 V
d) 40 V
.
Answer: b
Explanation: The electrolytes in ECM employ a working voltage up to 20 V.
71. Surface roughness depend on which of the following quantities?
a) Crystallographic irregularities
b) Alloy composition
c) Distribution of current density
d) All of the mentioned
.
Answer: d
Explanation: Surface roughness of machined surface in ECM depend on crystallographic irregularities, alloy composition, current density distribution, dislocations and grain boundaries.
72. For a better surface finish, which type of current distribution is required?
a) Even
b) Uneven
c) Even & Uneven
d) None of the mentioned
.
Answer: a
Explanation: More even distribution of the current density leads to a better surface finish.
73. Between which values does the frontal gap’s surface roughness vary?
a) 0.02 to 0.13 µm
b) 0.30 to 1.90 µm
c) 1.93 to 2.64 µm
d) 2.73 to 4.26 µm
.
Answer: b
Explanation: Surface roughness varies between 0.30 to 1.9 µm for frontal gap area.
74. Between which values does the side gap’s surface roughness vary?
a) >1 µm
b) >3 µm
c) >5 µm
d) >7 µm
.
Answer: c
Explanation: Surface roughness value is 5 µm or more for side gap areas.
75. In Electrochemical machining, larger grain size causes which type of finish?
a) Smoother
b) Rougher
c) Finer
d) All of the mentioned
.
Answer: b
Explanation: In ECM, larger grains cause rougher finish than finer grains.
76. Which type of gap width is necessary for a higher degree of accuracy?
a) Very small
b) Small
c) Medium
d) High
.
Answer: b
Explanation: A small gap width represents a high level of accuracy. Very small gap width results in sparks and short circuits.
77. Accuracy of machining is affected by, which of the following factors?
a) Material
b) Gap voltage
c) Feed rate
d) All of the mentioned
.
Answer: d
Explanation: Accuracy of the process is affected by material equivalent, gap voltage, feed rate, etc.
78. Which properties of electrolyte does not affect the accuracy of the process?
a) Temperature
b) Concentration
c) Non-reactive
d) Pressure
.
Answer: c
Explanation: Electrolyte must be reactive in order to carry on the reactions that occur at the electrodes.
79. For high process accuracy, which of the following factors are needed?
a) High feed rate
b) High conductivity
c) High feed rate & High conductivity
d) None of the mentioned
.
Answer: c
Explanation: For a higher degree of accuracy, there must be high feed rates and highly conductive electrolytes.
80. Tool insulation that __________ the side machining action is needed in the process of ECM.
a) Limits
b) Enhances
c) Maintains
d) None of the mentioned
.
Answer: a
Explanation: Tool insulation is needed, which limits the machining of other sides of work piece.
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81. If the current density is high as required, what type of machining occurs?
a) Pitting
b) Polishing
c) Etching
d) All of the mentioned
.
Answer: b
Explanation: When the current density is relatively high as required, then polishing occurs.
82. What happens when the current density is low in ECM?
a) Pitting occurs
b) Etching occurs
c) Pitting & Etching occurs
d) None of the mentioned
.
Answer: c
Explanation: When current density is lower than optimum, then etching and pitting occurs which are undesired.
83. Fine dimensional control can be obtained if throwing power of electrolyte is ___________
a) Low
b) Medium
c) High
d) Very high
.
Answer: a
Explanation: Throwing power of electrolyte must be less in order to obtain a fine dimensional control.
84. Passivation is done on electrolytes in order to form which of the following?
a) Passive layer on machined parts
b) Passive layer on cathode
c) Passive layer on machined parts & cathode
d) None of the mentioned
.
Answer: a
Explanation: Passivation is done on the electrolytes in order to form a passive film on machined parts.
85. If there is an increase in the electrolyte flow, what happens to the rate of film formation?
a) Increases
b) Decreases
c) Remains same
d) All of the mentioned
.
Answer: b
Explanation: An increase in electrolytic solution flow decreases the anodic product formation, which reduces the rate of film formation.
86. What are the typical dimensional tolerances for frontal gaps in ECM?
a) ± 0.01 mm
b) ± 0.025 mm
c) ± 0.13 mm
d) ± 0.25 mm
.
Answer: c
Explanation: The dimensional tolerances obtained for frontal gaps are ± 0.130 mm.
87. What are the tolerance values for the side gap in ECM?
a) ± 0.01 mm
b) ± 0.025 mm
c) ± 0.13 mm
d) ± 0.25 mm
.
Answer: d
Explanation: The dimensional tolerances obtained for side gaps are ± 0.25 mm.
88. What are the typical dimensional tolerances obtained in ECM when there is proper control of machining?
a) ± 0.01 mm
b) ± 0.025 mm
c) ± 0.13 mm
d) ± 0.25 mm
.
Answer: b
Explanation: The dimensional tolerances obtained by proper machining are ± 0.025 mm.
89. It is difficult to machine inner radii smaller than __________ and outer radii less than ________ in ECM.
a) 0.1 mm, 0.2 mm
b) 0.5 mm, 0.8 mm
c) 0.8 mm, 0.5 mm
d) 0.2 mm, 0.1 mm
.
Answer: c
Explanation: It is difficult to machine inner radii < 0.8mm and outer radii < 0.5mm.
90. What is the value of the overcut that is obtained using ECM?
a) 0.3 mm
b) 0.5 mm
c) 0.7 mm
d) 0.9 mm
.
Answer: b
Explanation: An overcut of 0.5 mm is obtained when machined using ECM.
91. If there is a change in the selected machining conditions, it will have impact on which of the following?
a) Process accuracy
b) Surface finish
c) Process accuracy & Surface finish
d) None of the mentioned
.
Answer: c
Explanation: Selected machining conditions should remain unchanged, because, it will have a direct impact on accuracy and surface finish.
92. Surface roughness depends on current density, which is affected by which of the following?
a) Tool feed rate
b) Gap voltage
c) Work piece material
d) All of the mentioned
.
Answer: d
Explanation: Roughness depend on current density, which is affected by tool feed rate, gap voltage, work material, pH number, temperature, conductivity and pressure.
93. Machining conditions leading to high accuracy are associated with ________ surface roughness and ________ productivity.
a) Greater, greater
b) Smaller, greater
c) Greater, smaller
d) Smaller, smaller
.
Answer: b
Explanation: Accuracy is associated with smaller surface roughness and greater machining productivity.
94. Non stationary behaviour of ECM is due to, which of the factors below?
a) Gas generation
b) Heating
c) Passivation
d) All of the mentioned
.
Answer: d
Explanation: Non stationary behaviour of ECM is due to the inter electrode gap conditions such as gas generation, passivation, heating and other electrode reactions.
95. For large components, actual machining time constitutes to how much percentage of the total machining time?
a) Very low
b) Low
c) Medium
d) High
.
Answer: d
Explanation: Actual machining time of large components constitutes to a high percentage of total machining time.
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96. What happens to the product cycle time, if the machining performance is improved?
a) Increases
b) Decreases
c) Remains same
d) None of the mentioned
.
Answer: b
Explanation: As the machining performance is improved, the time take for a product to complete its production cycle, decreases.
97. The cost of additional control hardware remain a _________ fraction of total machining cost.
a) Small
b) Large
c) Equal
d) None of the mentioned
.
Answer: a
Explanation: Cost of additional control hardware is very less, which constitutes to a small fraction in total machining cost.
98. With an increase in unmanned machining hours, what happens to the efficiency of ECM?
a) Increases
b) Reduces
c) Decreases
d) Increase and then decrease
.
Answer: a
Explanation: Increase in unmanned machining hours lead to a raise in efficiency of ECM.
99. State whether the following statement is true or false regarding the process control of ECM.
“In Electrochemical machining, increase in unmanned machining hours reduces the possibility of integration of process with CAD/CAM systems.”
a) True
b) False
.
Answer: b
Explanation: An increase in unmanned machining hours, enhances the process integration with CAD/CAM systems.
100. Which type of damage is caused by deterioration which is caused by spark?
a) Reparable
b) Irreparable
c) All of the mentioned
d) None of the mentioned
.
Answer: b
Explanation: Deterioration by sparking may cause irreparable damage to the work pieces.
101. Which of the following use ECM for different applications?
a) Gas turbines
b) Jet engines
c) Bio medical implants
d) All of the mentioned
.
Answer: d
Explanation: ECM has its applications in industries such as gas turbines, jet engines, automobiles, medical etc.
102. Which of the following processes can be done using ECM?
a) Die sinking
b) Profiling and contouring
c) Drilling and trepanning
d) All of the mentioned
.
Answer: d
Explanation: ECM can be used for die sinking, trepanning, drilling, contouring, grinding and profiling.
103. Which of the following material cannot be machined using ECM?
a) High strength alloys
b) Hardened steels
c) Nonconductive materials
d) All of the mentioned
.
Answer: c
Explanation: ECM can be used for machining high strength alloys and hardened steels which led to many cost-saving applications.
104. ECM is used to _________ the sharp edges produced after rough cuts.
a) Enhance
b) Dull
c) Improve
d) None of the mentioned
.
Answer: b
Explanation: Using deburring process through ECM, sharp edges are dulled, which are produced after rough cuts.
105. ECM is usually characterized as low accuracy machining, for which of the following reason?
a) Narrow gap width
b) Wider gap width
c) High current densities
d) All of the mentioned
.
Answer: b
Explanation: ECM is usually characterized as low accuracy machining because of its wider machining gap.
106. In micro ECM, which of the following is used as micro tool?
a) Electrolyte jet
b) Electrodes
c) Power supply
d) All of the mentioned
.
Answer: a
Explanation: Electrolyte jet in micro ECM acts as the micro tool for machining.
107. Micro ECM is used to machine which type of parts?
a) Large parts
b) Micro parts
c) Normal sized parts
d) All of the mentioned
.
Answer: b
Explanation: Micro ECM is used to machine micro parts which can be from micro scale to mesoscale in size.
108. Which of the following produces small indents and cavities using micro ECM?
a) Moving the work piece
b) Switching the pulse current
c) Moving the work piece & Switching the pulse current
d) None of the mentioned
.
Answer: c
Explanation: Indentation and cavitation can be done using micro ECM by moving the work piece or switching the pulse current.
109. What fraction of tool will always be in contact with the work piece?
a) Half
b) Full
c) No contact
d) Quarter
.
Answer: c
Explanation: Tool does not have any contact with the work piece in Electro chemical machining.
110. How much amount of wear is present in the tool used in Electrochemical machining?
a) No wear
b) Low
c) Medium
d) High
.
Answer: a
Explanation: The tool wear is absent in the tool used in ECM, since tool has no contact with the work piece.
111. 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: c
Explanation: In ECM, machining is done at low voltages, when compared to other processes.
112. 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: b
Explanation: Due to less electrode gap very small dimensions up to 0.05 mm can be controlled.
113. Complicated profiles can be machined in how many operations in Electrochemical machining?
a) Single
b) Double
c) Triple
d) Multiple
.
Answer: a
Explanation: One of the main advantage of ECM is, complicated profiles can be machined in a single operation itself.
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114. How much amount of thermal damage occurs to the work piece?
a) Small
b) Large
c) No thermal damage
d) Negligible amount
.
Answer: c
Explanation: As the temperatures are very low, no thermal damage occurs to the work piece material.
115. 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: b
Explanation: Hard conductive materials can be machined and nonconductive materials cannot be machined using ECM.
116. What are the requirements of labour for machining purpose in Electrochemical machining?
a) Low
b) Medium
c) High
d) Very high
.
Answer: a
Explanation: In electrochemical machining, labour requirements are low compared to conventional or traditional machining practices.
117. How much amount of energy is consumed in Electro chemical machining?
a) Very small
b) Small
c) Medium
d) Large
.
Answer: d
Explanation: Very huge amount of energy is required for ECM, which is nearly 100 times required for turning or drilling of steel.
118. 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: a
Explanation: In ECM, rates of material removal are slow compared to conventional methods.
119. 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: b
Explanation: Work piece needs to be cleaned and oiled just after the machining is done.
120. 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: d
Explanation: Removal of hydrogen, handling and containing the electrolyte and energy consumption are some of the limitations of ECM.
121. 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: b
Explanation: Duplication of tool is difficult in ECM, since it has side machining effects.
122. 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: c
Explanation: Electro chemical machining cannot produce sharp internal or external edges.
123. 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: a
Explanation: Electrolyte pumping through the narrow gaps gives rise to a large amount of forces on tool and work pieces.
124. 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: b
Explanation: Occupational health dangers are limited if ECM is done at appropriate conditions.
125. 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: d
Explanation: Electrolyte splashing, precipitation of solid matter, and toxic gas release is very harmful to the environment.
126. 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: c
Explanation: Contamination of skin and eyes may occur due to electrolyte splashing and toxic gas release.
127. 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: a
Explanation: By using NaNO3, deburring and die sinking can be done with more accuracy and high qualities are obtained.
128. 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: c
Explanation: Dissolution of metal containing chromate results nitrate reduction at cathode tool, which in turn produces toxic chromate and ammonia.
129. 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: a
Explanation: Slurries which mix with toxic compounds such as chromate and ammonia precipitates solid matter in the electrolyte solution.
130. 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: b
Explanation: The electrolyte which contain the solid precipitates needs to be disposed immediately, in order to avoid any damage to the environment.
131. 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: a
Explanation: When chromate containing metals dissolute, nitrate accumulate at cathode tool, which results in toxic chromate and ammonia compounds.
132. What is the full form of ECDR in advanced machining processes?
a) Electrochemical Dissolution
b) Electrochemical Drilling
c) Electrochemical Degradation
d) Electrochemical Devastation
.
Answer: b
Explanation: In advanced machining processes, full form of ECDR is Electrochemical Drilling.
133. 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: b
Explanation: Value of diameter produced using Electrochemical drilling, ranges between 1 to 20 mm.
134. 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: c
Explanation: Value of feed rates used in Electrochemical drilling, range between 1 to 5 mm/min.
135. 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: a
Explanation: In ECDR, tubular electrodes are used as cathodic tools for making holes in the materials.
136. 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: 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.
137. 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: 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.
138. 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: b
Explanation: Overcut is the difference between the diameter of hole produced in work piece and the diameter of tool.
139. 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: d
Explanation: High feed rates are recommended for smaller diametrical oversize and more accuracy.
140. 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: a
Explanation: If we use backward pressure for electrolyte flow, the overcut size decreases.
141. 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: 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.
142. 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: a
Explanation: In ECDR, as the gap increases, the electrical conductivity increases and the dissolution of material increases.
143. Electrolyte back pressure _________ the flow lines on work piece machined using ECDR.
a) Enhances
b) Eliminates
c) Maintains
d) Increases
.
Answer: b
Explanation: Electrolyte back pressure eliminates the flow lines on the machined surfaces which is a major advantages of ECDR.
144. What happens to the roundness error if we use the rotation of ECDR tool?
a) Increases
b) Remains same
c) Decreases
d) Enhances
.
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.
145. 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: c
Explanation: Sparking, which occur due to very less gap between tool and work piece, which damages both the parts in ECDR.
146. 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: d
Explanation: Current efficiencies less than 100 percent may be related to gas evolution, passive oxide formation, which in turn lead to less dissolution.
147. 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: c
Explanation: Full form of STEM in advanced machining processes is Shaped tube electrolytic machining.
148. Material is removed on which basis, in Shaped tube electrolytic machining?
a) Dissolution
b) Vaporization
c) Abrasion
d) Erosion
.
Answer: a
Explanation: In STEM, dissolution takes place when a potential difference is applied between the anodic work piece and cathodic tool.
149. 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: d
Explanation: Electrolytes used in STEM are sulphuric acid, nitric acid and hydrochloric acids.
150. What is the percentage of electrolyte dissolved in water?
a) 1 – 5%
b) 10 – 25%
c) 40 – 70%
d) 75 – 90%
.
Answer: b
Explanation: Concentration of electrolyte, used in STEM, is 10 – 25% weight in water.
151. 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: c
Explanation: The temperature of sulphuric acids used in the STEM process may be around 38 oC.
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152. 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: b
Explanation: Temperature of acids used in STEM, other than sulphuric acid, is about 21 oC.
153. 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: c
Explanation: Values of pressure used in the STEM process, range between 275 – 500 kPa.
154. 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: b
Explanation: In STEM, voltage values used for the process to carry on, range between 8 – 14 V.
155. 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: b
Explanation: Reverse voltages used in STEM are 0.1 – 1 times the forward voltages, used in STEM.
156. 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: c
Explanation: Feed rates used in STEM, range between 0.75 – 3 mm/min.
157. 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: b
Explanation: The hole sizes that can be machined using STEM process, range between 0.5 – 6 mm.
158. 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: 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.
159. 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: 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.
160. 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: 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.
161. 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: 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.
162. 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: a
Explanation: In advanced machining processes, full form of ES drilling is Electrostream drilling.
163. 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: 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.
164. 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: b
Explanation: Electrostream drilling uses a gas nozzle, whose diameter ranges between 0.025 – 0.5 mm.
165. 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: a
Explanation: The diameter of nozzle used is smaller than the hole size required to be drilled in work piece.
166. 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: b
Explanation: Unlike the case of STEM process, which uses coated Ti tube as cathode, ES drilling used platinum wire as cathode electrode.
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167. 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: b
Explanation: Commonly used electrolytes have a concentration between 12 to 20wt %.
168. 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: a
Explanation: Hydrochloric acids are used for machining Al and its alloys and sulphuric acid is recommended for other metals.
169. 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: d
Explanation: Haste alloy, Rene alloy, Inconel, carbon and stainless steels are the materials machined using sulphuric acid.
170. 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: c
Explanation: Electrolyte pressure values must range between 275 – 400 kPa for ES drilling to take place.
171. 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: d
Explanation: Acid temperature, pressure, concentration and feed rate are to be carefully monitored for satisfactory machining.
172. 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: c
Explanation: Voltage values used in ES drilling, range between 70 to 150 V.
173. 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: b
Explanation: Feed rate values used in ES drilling, range between 0.75 to 2.5 mm/min.
174. 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: d
Explanation: Rates of material removal are high, when feed rates are high and larger tool diameters.
175. 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: b
Explanation: The normal hole depth tolerances obtained in ES drilling, range between ± 0.05 mm.
176. How many holes can be drilled simultaneously using ES drilling process?
a) One hole
b) Two holes
c) Three holes
d) Multiple holes
.
Answer: d
Explanation: Depending upon the size of diameters, multiple holes can be drilled using ES drilling.
177. 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: b
Explanation: In advanced machining processes, full form of ECJD is Electrochemical Jet Drilling.
178. 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: c
Explanation: Electrochemical jet drilling is the process used for producing fine holes, having diameter to depth ratio of 1:12.
179. 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: a
Explanation: ES drilling has a diameter to depth ratio of 1:100, while ECJD has a ratio of 1:12.
180. 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: c
Explanation: Material is removed by spraying electrolyte through the cathode, in Electrochemical jet drilling.
181. What is the material removal mechanism used in Electrochemical jet drilling?
a) Abrasion
b) Dissolution
c) Vaporization
d) Erosion
.
Answer: b
Explanation: Electrochemical dissolution is the means of material removal in Electrochemical jet drilling.
182. 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: c
Explanation: The optimum range of voltages used in Electrochemical jet drilling are between 400 to 800 V.
183. 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: 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.
184. 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: a
Explanation: Diameter of the hole produced, depend up on the throwing power of electrolyte.
185. 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: c
Explanation: In ECJD, the holes produced are nearly 4 times that of the electrolyte jet diameter used in the process.
186. What is the value of the ratio of hole diameter to capillary diameter in ECJD?
a) 2
b) 4
c) 6
d) 8
.
Answer: a
Explanation: Generally, ratio of hole diameter to capillary diameter in ECJD is 2.
187. 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: b
Explanation: In Electrochemical jet drilling tapers produced are about 5 to 10 included angles.
188. 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: b
Explanation: In ECJD, enough room is required for the exit of electrolyte, preferably in the form of spray.
189. 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: d
Explanation: As this is an electrochemical dissolution process, electrodes should not be in contact in order to avoid sparking.
190. In advanced machining processes, full form of ECDB is _________
a) Electrochemical Drill buffing
b) Electrochemical Dimension Breaking
c) Electrochemical Deburring
d) Electrochemical Dimensioning
.
Answer: c
Explanation: In advanced machining processes, full form of ECDB is Electrochemical Deburring.
191. 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: d
Explanation: Different methods used for deburring include vibratory and barrel finishing, tumbling, water blasting, Abrasive flow machining, Electrochemical deburring and many more.
192. 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: c
Explanation: Anode is the electrode, on which, the process of deburring is done.
193. Burrs are removed at which amount of current densities below?
a) Very low
b) Low
c) High
d) Medium
.
Answer: c
Explanation: High current densities are required to remove the burrs from the work pieces.
194. 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: b
Explanation: Dimensions of the part are changes by the removal of burrs leaving a controlled radius.
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195. To which components mentioned below, ECDM can be applied?
a) Spline shafts
b) Milled components
c) Drilled holes
d) All of the mentioned
.
Answer: d
Explanation: ECDB can be applied to gears, spline shafts, milled components, drilled holes, and punched blanks.
196. 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: c
Explanation: Values of speeds of deburring, range between 400 to 500 mm/min.
197. 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: b
Explanation: The normal cycle times are between 30 to 45 s after which, spindle is retracted and part is removed.
198. 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: c
Explanation: Burr height of around 0.5 mm can be removed using ECDB process.
199. 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: b
Explanation: Burr of height 0.5 mm to a radius of 0.05 to 0.2 mm can be removed using ECDB.
200. 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: c
Explanation: Surface roughness obtained in ECDB process is about 2 to 4 µm
201. 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: b
Explanation: Pressure of electrolyte used in ECDB is maintained between 0.3 to 0.5 MPa.
202. 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: c
Explanation: Value of voltage used in ECDB process ranges from 12 to 24 V.
203. 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: b
Explanation: Current densities used in ECDB process range between 5 – 10 A/cm2.
204. 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: d
Explanation: Sodium nitrite, sodium nitrate and sodium chloride are the electrolytes used in ECDB process.
205. 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: c
Explanation: The inter electrode gap maintained in ECDB process, range between 0.30 – 0.50 mm.
206. 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: 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.
207. 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: d
Explanation: All the materials mentioned above, can be machined using ECDB process.
208. In ECDB process, rotating and feeding the tool electrode __________ the deburring process.
a) Enhances
b) Degrades
c) Damages
d) All of the mentioned
.
Answer: a
Explanation: Rotating and feeding the tool in ECDB process, enhances the process of deburring.
209. 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: d
Explanation: ECDB ensures the removal of burrs art required accuracy, uniformity, proper radius and clean edges.
210. 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: d
Explanation: Increased product quality and reliability, reduced labour costs, elimination of costly hand deburring etc.., are some of the advantages of ECDB.
211. 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: b
Explanation: Electrochemical deburring can be automated for higher productivity.