Unconventional Machine Process Set 22

Mechanical Engineering

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This set of Unconventional Machine Process (UMP) Multiple Choice Questions & Answers (MCQs) focuses on Unconventional Machine Process Set 22

Q1 | Compared to the tool used in ECM, how should be the work piece size?
  • greater than
  • smaller than
  • same as tool
  • none of the mentioned
Answer: greater than
Explaination:
by an oversize, work piece size is expected to be greater than tool size.
Q2 | Which of the following factors are used to determine the tool geometry?
  • required shape
  • electrical conductivity
  • tool feed rate
  • all of the mentioned
Answer: all of the mentioned
Explaination:
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.
Q3 | Which of the following are the simplest methods for applying the insulation on tools?
  • spraying
  • dipping
  • all of the mentioned
  • none of the mentioned
Answer: all of the mentioned
Explaination:
in ecm, dipping or spraying are the simplest methods for insulating the tools.
Q4 | What are the main functions of electrolyte in Electrochemical machining?
  • conduct machining current
  • removal of debris
  • maintaining constant temperature
  • all of the mentioned
Answer: all of the mentioned
Explaination:
main functions of electrolyte are conducting machine current, removing the debris, carrying away the heat, maintaining constant temperature.
Q5 | Electrolytic solution should ensure which type of anodic dissolution?
  • uniform
  • non-uniform
  • low speed
  • none of the mentioned
Answer: uniform
Explaination:
uniform and high speed anodic dissolution must be ensured by the electrolyte.
Q6 | State whether the following statement is true or false regarding the electrolytic solution. “In ECM, formation of passive film is recommended.”
  • true
  • false
Answer: false
Explaination:
electrolytic solution should avoid formation of passive layers on anode.
Q7 | Which type of electrical conductivity is necessary for electrolytic solution?
  • low
  • medium
  • high
  • none of the mentioned
Answer: high
Explaination:
high electrical conductivity is needed for electrolytic solution in ecm.
Q8 | What are the other features of electrolytic solution in ECM?
  • non toxic
  • less erosive
  • less viscous
  • all of the mentioned
Answer: all of the mentioned
Explaination:
electrolytic solution should be nontoxic, less viscous and less erosive.
Q9 | How much should be the electrolytic solution?
  • highly expensive
  • inexpensive
  • all of the mentioned
  • none of the mentioned
Answer: inexpensive
Explaination:
electrolyte must be inexpensive and available at ease.
Q10 | Which are the most common electrolytes used in Electrochemical machining?
  • sodium chloride
  • sodium nitride
  • sodium hydroxide
  • all of the mentioned
Answer: all of the mentioned
Explaination:
electrolytes such as sodium chloride, sodium nitride, sodium hydroxide are some of the electrolytes used in ecm.
Q11 | Selection of electrolyte does not depend on which of the following factors?
  • work piece material
  • dimensional tolerance
  • heat affected zones
  • machining productivity
Answer: heat affected zones
Explaination:
selection of electrolyte depend up on work piece material, dimensional tolerance, machining productivity and surface finish required.
Q12 | What must be the value of electrolytic temperature in ECM?
  • 2 to 14oc
  • 22 to 45oc
  • 46 to 57oc
  • 62 to 76oc
Answer: 22 to 45oc
Explaination:
temperature of electrolyte should range between 22 to 45oc.
Q13 | What must be the value of the pressure of electrolytic solution used in ECM?
  • 1 to 10 kpa
  • 10 to 80 kpa
  • 100 to 200 kpa
  • 300 to 400 kpa
Answer: 100 to 200 kpa
Explaination:
value of pressure of electrolytic solution must range between 100 to 200 kpa.
Q14 | What must be the value of velocity of the electrolytic solution?
  • 10 to 15 m/s
  • 25 to 50 m/s
  • 60 to 100 m/s d) 120 to 200 m/s
Answer: 25 to 50 m/s
Explaination:
typical velocity of the electrolytic solution must range between 25 to 50 m/sec.
Q15 | Local metal removal rates are high at which gap locations mentioned below?
  • small gap
  • medium gap
  • large gap
  • none of the mentioned
Answer: small gap
Explaination:
local metal removal rates are high at small gap locations in ecm.
Q16 | When local metal removal rates are high, how will be the current density and current efficiency?
  • high
  • medium
  • low
  • very low
Answer: high
Explaination:
when the local metal removal rates are high then current density and efficiency are also high.
Q17 | Current efficiency depends on which of the following in ECM?
  • anodic material
  • electrolyte
  • anodic material & electrolyte
  • none of the mentioned
Answer: anodic material & electrolyte
Explaination:
current efficiency in ecm depend on electrolyte and anodic material used.
Q18 | In the following ratios of metal dissolved amounts, which one represent the current efficiency?
  • observed to theoretical
  • theoretical to observed
  • all of the mentioned
  • none of the mentioned
Answer: observed to theoretical
Explaination:
in electrochemical machining, current efficiency is the ratio of observed amount of metal dissolved to the theoretical amount of metal dissolved.
Q19 | Apparent current efficiency is due to which of the following factors?
  • choice of wrong valence
  • passivation of anodic surface
  • gas evolution at anode
  • all of the mentioned
Answer: all of the mentioned
Explaination:
current efficiency may be apparent because of choice of wrong valence, passivation of anodic surface or gas evolution at anodic surface.
Q20 | State whether the following statement is true or false regarding the working principles. “In ECM, grain boundary attacks remove the grains through electrolytic forces.”
  • true
  • false
Answer: true
Explaination:
in ecm, grain boundary attacks are the cause for removal of grains by electrolytic forces.
Q21 | In ECM, gap increase proportional to which relation of time below?
  • square of time
  • square root of time
  • cube of time
  • cube root of time
Answer: square root of time
Explaination:
in electrochemical machining, gap increases proportional to the square root of time.
Q22 | At constant feed rates what happens to gap thickness?
  • increases
  • decreases
  • becomes constant
  • none of the mentioned
Answer: becomes constant
Explaination:
at constant feed rate, work piece becomes stationary and thus the gap thickness becomes constant.
Q23 | At constant gap thickness material removal becomes equal to feed rate. What is this gap called?
  • equal gap
  • equilibrium gap
  • unique gap
  • narrow gap
Answer: equilibrium gap
Explaination:
when rate of material removal per unit area is same as feed rate, then corresponding thickness is called as equilibrium thickness indicated by ‘ye’.
Q24 | If the gap thickness is greater than equilibrium thickness what will be MRR?
  • mrr is less than feed rate
  • mrr is greater than feed rate
  • mrr is equal to feed rate
  • none of the mentioned
Answer: mrr is less than feed rate
Explaination:
when gap thickness is greater than equilibrium thickness, mrr will be less than feed rate.
Q25 | During ECM drilling, decrease in feed rates lead to which type of machining gaps?
  • wider
  • narrow
  • small
  • none of the mentioned
Answer: wider
Explaination:
decrease in feed rate lead to wider gap thickness in ecm drilling.
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