This set of Advanced Machining Processes Multiple Choice Questions & Answers (MCQs) focuses on “ECM-Process Characteristics – 1”.
1. 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
View Answer
Explanation: ECD phase occurs by the movement of ions between the two electrodes.
2. 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
View Answer
Explanation: Proper chemical composition of electrolyte and proper current density are responsible for better surface finish and accuracy.
3. For alloys, which type of electrolyte is used in ECM?
a) Single component
b) Double component
c) Multi component
d) Triple component
View Answer
Explanation: Depending up on the elements in an alloy multi component electrolytes are used.
4. 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
View Answer
Explanation: Nickel is a metal suggested by Khayry, which can be machined at 100% current efficiency, if current density is 25 A/cm2.
5. When the electrolyte flow is low, what happens to the current efficiency?
a) Increases
b) Decreases
c) Remains same
d) Increase and then decrease
View Answer
Explanation: In ECM, if the electrolyte flow is low, current efficiency is reduced due to the accumulation of machining products within the gap.
6. 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 %
View Answer
Explanation: While machining Ti using NaCl electrolyte, current efficiencies of 10 – 20 percent are obtained.
7. 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
View Answer
Explanation: Machinability is increased, when electrolyte is heated, as heating increases the specific conductivity of the electrolyte.
8. In practice, what must be the temperature of electrolyte used in ECM?
a) 10 – 20oC
b) 20 – 40oC
c) 60 – 80oC
d) 80 – 100oC
View Answer
Explanation: Temperature of electrolyte used in ECM must not exceed 60 – 70oC.
9. 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
View Answer
Explanation: Moderate level of pH of electrolyte used in ECM range between 4 – 10.
10. What must be the working voltage in Electrochemical machining?
a) 10 V
b) 20 V
c) 30 V
d) 40 V
View Answer
Explanation: The electrolytes in ECM employ a working voltage up to 20 V.
11. 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
View Answer
Explanation: Surface roughness of machined surface in ECM depend on crystallographic irregularities, alloy composition, current density distribution, dislocations and grain boundaries.
12. For a better surface finish, which type of current distribution is required?
a) Even
b) Uneven
c) Even & Uneven
d) None of the mentioned
View Answer
Explanation: More even distribution of the current density leads to a better surface finish.
13. 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
View Answer
Explanation: Surface roughness varies between 0.30 to 1.9 µm for frontal gap area.
14. Between which values does the side gap’s surface roughness vary?
a) >1 µm
b) >3 µm
c) >5 µm
d) >7 µm
View Answer
Explanation: Surface roughness value is 5 µm or more for side gap areas.
15. In Electrochemical machining, larger grain size causes which type of finish?
a) Smoother
b) Rougher
c) Finer
d) All of the mentioned
View Answer
Explanation: In ECM, larger grains cause rougher finish than finer grains.
Sanfoundry Global Education & Learning Series – Advanced Machining.
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