This set of Advanced Machining Processes Multiple Choice Questions & Answers (MCQs) focuses on “ECM-Process Characteristics – 2”.
1. Which type of gap width is necessary for a higher degree of accuracy?
a) Very small
b) Small
c) Medium
d) High
View Answer
Explanation: A small gap width represents a high level of accuracy. Very small gap width results in sparks and short circuits.
2. Accuracy of machining is affected by, which of the following factors?
a) Material
b) Gap voltage
c) Feed rate
d) All of the mentioned
View Answer
Explanation: Accuracy of the process is affected by material equivalent, gap voltage, feed rate, etc.
3. Which properties of electrolyte does not affect the accuracy of the process?
a) Temperature
b) Concentration
c) Non-reactive
d) Pressure
View Answer
Explanation: Electrolyte must be reactive in order to carry on the reactions that occur at the electrodes.
4. 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
View Answer
Explanation: For a higher degree of accuracy, there must be high feed rates and highly conductive electrolytes.
5. 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
View Answer
Explanation: Tool insulation is needed, which limits the machining of other sides of work piece.
6. If the current density is high as required, what type of machining occurs?
a) Pitting
b) Polishing
c) Etching
d) All of the mentioned
View Answer
Explanation: When the current density is relatively high as required, then polishing occurs.
7. 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
View Answer
Explanation: When current density is lower than optimum, then etching and pitting occurs which are undesired.
8. Fine dimensional control can be obtained if throwing power of electrolyte is ___________
a) Low
b) Medium
c) High
d) Very high
View Answer
Explanation: Throwing power of electrolyte must be less in order to obtain a fine dimensional control.
9. 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
View Answer
Explanation: Passivation is done on the electrolytes in order to form a passive film on machined parts.
10. 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
View Answer
Explanation: An increase in electrolytic solution flow decreases the anodic product formation, which reduces the rate of film formation.
11. 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
View Answer
Explanation: The dimensional tolerances obtained for frontal gaps are ± 0.130 mm.
12. 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
View Answer
Explanation: The dimensional tolerances obtained for side gaps are ± 0.25 mm.
13. 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
View Answer
Explanation: The dimensional tolerances obtained by proper machining are ± 0.025 mm.
14. 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
View Answer
Explanation: It is difficult to machine inner radii < 0.8mm and outer radii < 0.5mm.
15. 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
View Answer
Explanation: An overcut of 0.5 mm is obtained when machined using ECM.
Sanfoundry Global Education & Learning Series – Advanced Machining.
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