Unconventional Machine Process Set 23

Mechanical Engineering

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This set of Unconventional Machine Process (UMP) Multiple Choice Questions & Answers (MCQs) focuses on Unconventional Machine Process Set 23

Q1 | Too small gap causes which of the following effects?
  • sparking
  • short circuit
  • sparking & short circuit
  • none of the mentioned
Answer: sparking & short circuit
Explaination:
sparking or short circuit occurs when the gap is too small
Q2 | Electro chemical dissolution phase starts with the movement of ions between which two components?
  • cathode and anode
  • cathode and power source
  • power source and anode
  • power source and electrolyte
Answer: cathode and anode
Explaination:
ecd phase occurs by the movement of ions between the two electrodes.
Q3 | Better surface finish and higher accuracy depend on which of the factors below?
  • chemical composition of the electrolyte
  • current density
  • all of the mentioned
  • none of the mentioned
Answer: all of the mentioned
Explaination:
proper chemical composition of electrolyte and proper current density are responsible for better surface finish and accuracy.
Q4 | For alloys, which type of electrolyte is used in ECM?
  • single component
  • double component
  • multi component
  • triple component
Answer: multi component
Explaination:
depending up on the elements in an alloy multi component electrolytes are used.
Q5 | Nickel can be machined with 100% current efficiency, when current density value is
  • 10 a/cm2
  • 25 a/cm2
  • 45 a/cm2
  • 80 a/cm2
Answer: 25 a/cm2
Explaination:
nickel is a metal suggested by khayry, which can be machined at 100% current efficiency, if current density is 25 a/cm2.
Q6 | When the electrolyte flow is low, what happens to the current efficiency?
  • increases
  • decreases
  • remains same
  • increase and then decrease
Answer: decreases
Explaination:
in ecm, if the electrolyte flow is low, current efficiency is reduced due to the accumulation of machining products within the gap.
Q7 | When machining Ti, in Nacl electrolyte, what values of current efficiencies are obtained?
  • 10 – 20 %
  • 20 – 30 %
  • 30 – 50 %
  • 50 – 80 %
Answer: 10 – 20 %
Explaination:
while machining ti using nacl electrolyte, current efficiencies of 10 – 20 percent are obtained.
Q8 | State whether the following statement is true or false about electrolyte in ECM. “Machinability in ECM is enhanced, when electrolyte is heated.”
  • true
  • false
Answer: true
Explaination:
machinability is increased, when electrolyte is heated, as heating increases the specific conductivity of the electrolyte.
Q9 | What must be the working voltage in Electrochemical machining?
  • 10 v
  • 20 v
  • 30 v
  • 40 v
Answer: 20 v
Explaination:
the electrolytes in ecm employ a working voltage up to 20 v.
Q10 | Surface roughness depend on which of the following quantities?
  • crystallographic irregularities
  • alloy composition
  • distribution of current density
  • all of the mentioned
Answer: all of the mentioned
Explaination:
surface roughness of machined surface in ecm depend on crystallographic irregularities, alloy composition, current density distribution, dislocations and grain boundaries.
Q11 | For a better surface finish, which type of current distribution is required?
  • even
  • uneven
  • even & uneven
  • none of the mentioned
Answer: even
Explaination:
more even distribution of the current density leads to a better surface finish.
Q12 | Between which values does the side gap’s surface roughness vary?
  • >1 µm
  • >3 µm
  • >5 µm
  • >7 µm
Answer: >5 µm
Explaination:
surface roughness value is 5 µm or more for side gap areas.
Q13 | In Electrochemical machining, larger grain size causes which type of finish?
  • smoother
  • rougher
  • finer
  • all of the mentioned
Answer: rougher
Explaination:
in ecm, larger grains cause rougher finish than finer grains
Q14 | Which type of gap width is necessary for a higher degree of accuracy?
  • very small
  • small
  • medium
  • high
Answer: small
Explaination:
a small gap width represents a high level of accuracy. very small gap width results in sparks and short circuits.
Q15 | Accuracy of machining is affected by, which of the following factors?
  • material
  • gap voltage
  • feed rate
  • all of the mentioned
Answer: all of the mentioned
Explaination:
accuracy of the process is affected by material equivalent, gap voltage, feed rate, etc.
Q16 | Which properties of electrolyte does not affect the accuracy of the process?
  • temperature
  • concentration
  • non-reactive
  • pressure
Answer: non-reactive
Explaination:
electrolyte must be reactive in order to carry on the reactions that occur at the electrodes.
Q17 | For high process accuracy, which of the following factors are needed?
  • high feed rate
  • high conductivity
  • high feed rate & high conductivity
  • none of the mentioned
Answer: high feed rate & high conductivity
Explaination:
for a higher degree of accuracy, there must be high feed rates and highly conductive electrolytes.
Q18 | Tool insulation that                      the side machining action is needed in the process of ECM.
  • limits
  • enhances
  • maintains
  • none of the mentioned
Answer: limits
Explaination:
tool insulation is needed, which limits the machining of other sides of work piece.
Q19 | If the current density is high as required, what type of machining occurs?
  • pitting
  • polishing
  • etching
  • all of the mentioned
Answer: polishing
Explaination:
when the current density is relatively high as required, then polishing occurs.
Q20 | What happens when the current density is low in ECM?
  • pitting occurs
  • etching occurs
  • pitting & etching occurs
  • none of the mentioned
Answer: pitting & etching occurs
Explaination:
when current density is lower than optimum, then etching and pitting occurs which are undesired.
Q21 | Fine dimensional control can be obtained if throwing power of electrolyte is
  • low
  • medium
  • high
  • very high
Answer: low
Explaination:
throwing power of electrolyte must be less in order to obtain a fine dimensional control.
Q22 | Passivation is done on electrolytes in order to form which of the following?
  • passive layer on machined parts
  • passive layer on cathode
  • passive layer on machined parts & cathode
  • none of the mentioned
Answer: passive layer on machined parts
Explaination:
passivation is done on the electrolytes in order to form a passive film on machined parts.
Q23 | If there is an increase in the electrolyte flow, what happens to the rate of film formation?
  • increases
  • decreases
  • remains same
  • all of the mentioned
Answer: decreases
Explaination:
an increase in electrolytic solution flow decreases the anodic product formation, which reduces the rate of film formation.
Q24 | It is difficult to machine inner radii smaller than                      and outer radii less than
  • 0.1 mm, 0.2 mm
  • 0.5 mm, 0.8 mm
  • 0.8 mm, 0.5 mm
  • 0.2 mm, 0.1 mm
Answer: 0.8 mm, 0.5 mm
Explaination:
it is difficult to machine inner radii < 0.8mm and outer radii < 0.5mm.
Q25 | What is the value of the overcut that is obtained using ECM?
  • 0.3 mm
  • 0.5 mm
  • 0.7 mm
  • 0.9 mm
Answer: 0.5 mm
Explaination:
an overcut of 0.5 mm is obtained when machined using ecm
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