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Machining Processes MCQ Set 1

1. After the explosion is over, how is the debris carried away?
a) Evaporation
b) Fresh dielectric
c) Old dielectric
d) All of the mentioned

View Answer

Answer: b [Reason:] Debris is carried away by the fresh dielectric that rushes in.

2. The layer formed when unexpelled molten metal solidifies is known as _____.
a) Reabsorbed layer
b) Recast layer
c) Unevaporated layer
d) Condensed layer

View Answer

Answer: b [Reason:] Unexpelled molten metal solidifies to form a layer known as recast layer.

3. Amount of material removed from anode and cathode depend on which of the following?
a) Electrons
b) Positive ions
c) All of the mentioned
d) None of the mentioned

View Answer

Answer: c [Reason:] The amount of material removed from electrodes depend on the contribution of the charged ions.

4. What happens when the electron current predominates in the discharge?
a) More anodic removal
b) More cathodic removal
c) Remains same
d) All of the mentioned

View Answer

Answer: a [Reason:] When electron current predominates the electrical discharge, anodic material removal is greater than cathodic material.

5. Between what values mentioned below, do the discharges and sparks usually vary?
a) 1 and 10,000
b) 500 and 500,000
c) 500,000 and 1,000,000
d) None of the mentioned

View Answer

Answer: b [Reason:] Frequency of discharges or sparks generally vary between 500 and 500,000 sparks per second.

6. What is the value of gap maintained between the electrodes when we use servo mechanism?
a) 10 – 100 µm
b) 100 – 200 µm
c) 200 – 500 µm
d) 500 – 1000 µm

View Answer

Answer: c [Reason:] In EDM, value of gap maintained between the electrodes range between 200 and 500 µm.

7. Based on the electrode gap, which of the following electric pulses are generated?
a) Open Circuit pulses
b) Sparks
c) Arcs
d) All of the mentioned

View Answer

Answer: d [Reason:] Based on the electrode gap, electric pulses are distinguished which are – circuit pulses, sparks, arcs and short circuits.

8. State whether following statement is true or false regarding EDM.
“In Electro discharge machining, electric pulses generated affect the material removal.”
a) True
b) False

View Answer

Answer: a [Reason:] In Electro discharge machining, electric pulses generated have an impact on the material removal.

9. Open gap voltages contribute to how much amount of material removal?
a) 20 %
b) 50 %
c) 70 %
d) No contribution

View Answer

Answer: d [Reason:] Open gap voltage that occur at too large distances do not contribute to any material removal.

10. When the electrode gap is too small or electrodes are in contact, how much material is removed?
a) 10%
b) 20%
c) 30%
d) No material removed

View Answer

Answer: d [Reason:] When electrodes come in contact with one another, short circuits occur and material removed is not possible.

11. Which components mentioned below are affected due to arcs?
a) Work piece
b) Tool
c) All of the mentioned
d) None of the mentioned

View Answer

Answer: c [Reason:] Arcs are believed to occur at same spots on electrode surfaces which damage both tool and work piece.

12. Which of the following pulses contribute to the desired material removal in EDM?
a) Open circuit pulses
b) Short circuits
c) Arcs
d) Sparks

View Answer

Answer: d [Reason:] The sparks are the one which contribute to the desired material removal in Electro discharge machining.

Machining Processes MCQ Set 2

1. Which of the following is a major difficulty in the Electro discharge machining process?
a) Proper sparks
b) Abnormal discharges
c) Optimum feed rates
d) No burr

View Answer

Answer: b [Reason:] Avoidance of abnormal discharges has become a major difficulty in Electro discharge machining process.

2. What has been done to the off time when there is a no-load voltage of electric discharge?
a) Increased
b) Decreased
c) Reduced
d) Remains same

View Answer

Answer: a [Reason:] The off time of pulse is increased in order to avoid the abnormal electric discharges.

3. In a simple application which of the following parameters are inputs?
a) Pulse duration and current
b) Normal and abnormal pulses
c) All of the mentioned
d) None of the mentioned

View Answer

Answer: a [Reason:] Inputs used are pulse duration and current in a simple application.

4. In a simple application which of the following parameters are outputs?
a) Pulse duration and current
b) Normal and abnormal pulses
c) All of the mentioned
d) None of the mentioned

View Answer

Answer: a [Reason:] Outputs used are normal and abnormal pulses in a simple application.

5. Which of the following are correlated with the machining conditions at output stage?
a) Machining depth
b) Surface roughness
c) Accuracy
d) All of the mentioned

View Answer

Answer: d [Reason:] Machining depth, surface roughness, accuracy are correlated with the machining conditions at the output stage.

6. How are EDM’s levels of integration when compared to conventional machining?
a) Slower rate
b) Faster rate
c) Same rate
d) None of the mentioned

View Answer

Answer: a [Reason:] EDM’s levels of computer integration is at a slower rate when compared to conventional machining processes.

7. Manufacturing of tool electrode undergoes which of the following processes?
a) Milling
b) Turning
c) Finishing
d) All of the mentioned

View Answer

Answer: d [Reason:] The tool electrode manufacturing used in EDM has to undergo the basic production processes such as milling, turning and finishing.

8. High temperatures produced in the working gap results in which of the following potentials?
a) Hazardous smoke
b) Toxic vapours
c) Aerosols
d) All of the mentioned

View Answer

Answer: d [Reason:] The temperatures in the working gap increases leading to hazardous smoke, vapours and aerosols.

9. Hydro carbons present in the dielectric fluid have impact on which of the body parts?
a) Eyes
b) Teeth
c) Skin
d) Nails

View Answer

Answer: c [Reason:] Hydrocarbons present in dielectric fluids of EDM will have a negative impact on the skin in our body.

10. What happens to the Electro discharge machining process under unfavourable working conditions?
a) Will remain stable
b) Explosion may occur
c) Machining rate increases
d) Nothing happens

View Answer

Answer: b [Reason:] Explosion occurs if Electro discharge machining is done under unfavourable process variables and conditions.

11. Reduction in the electrical energy consumption will have impact on which aspects mentioned below?
a) Environmental
b) Economic
c) All of the mentioned
d) None of the mentioned

View Answer

Answer: c [Reason:] The reduction of electric energy consumption has economic as well as environmental benefits.

Machining Processes MCQ Set 3

1. On which of the following factors do the craters depend?
a) Physical properties
b) Mechanical properties
c) Composition of medium
d) All of the mentioned

View Answer

Answer: d [Reason:] In EDM, craters depend on the physical and mechanical properties of material and composition of medium.

2. The maximum depth of damaged layer is how many times that of average surface roughness?
a) 1.5 time
b) 2 times
c) 2.5 times
d) 3 times

View Answer

Answer: c [Reason:] Depth of damaged layer is two and half times the average surface roughness value.

3. What happens to the surface roughness values if the MRR increases in EDM?
a) Increases
b) Decreases
c) Decrease and increase
d) None of the mentioned

View Answer

Answer: a [Reason:] In EDM, the surface roughness values increases linearly with increase in the material removal rates.

4. State whether following statement is true or false regarding the surface roughness in EDM.
“In EDM, graphite electrodes produce smoother surfaces than metal ones.”
a) True
b) False

View Answer

Answer: b [Reason:] In EDM, graphite electrodes produce rougher surfaces than that of the metal ones.

5. In Electro discharge machining, what happens to the surface finish if the pulse energy is decreased?
a) Reduces
b) Decreases
c) Improves
d) None of the mentioned

View Answer

Answer: c [Reason:] In Electro discharge machining, the surface finish improves if the pulse energy is decreased.

6. Using of a mate electrode in Electro discharge machining _____ the surface roughness of material.
a) Increases
b) Decreases
c) Enhances
d) None of the mentioned

View Answer

Answer: b [Reason:] By using a mate electrode in Electro discharge machining, the surface roughness values are decreased.

7. What happens to the surface roughness if oxygen gas is introduced in the gap?
a) Increases
b) Decreases
c) Decrease and then increase
d) All of the mentioned

View Answer

Answer: b [Reason:] In EDM, surface roughness increases with the supply of oxygen gas in gaps.

8. By how much percent surface roughness is reduced if we use proper dielectric flow?
a) 25%
b) 50%
c) 75%
d) 100%

View Answer

Answer: b [Reason:] In Electro discharge machining, if we use a proper dielectric fluid flow, surface roughness is decreased by 50 percent.

9. What are the tolerance values obtained by machining using EDM?
a) ± 10 mm
b) ± 15 mm
c) ± 25 mm
d) ± 40 mm

View Answer

Answer: c [Reason:] The tolerance values of ± 25 mm are obtained when we machine components using EDM.

10. How much extra tolerances are achieved when we choose proper variables?
a) ± 5 mm
b) ± 10 mm
c) ± 15 mm
d) ± 20 mm

View Answer

Answer: a [Reason:] Extra tolerances of ± 5 mm are obtained with proper choice of process variables.

Machining Processes MCQ Set 4

1. What is the full form of ECDR in advanced machining processes?
a) Electrochemical Dissolution
b) Electrochemical Drilling
c) Electrochemical Degradation
d) Electrochemical Devastation

View Answer

Answer: b [Reason:] In advanced machining processes, full form of ECDR is Electrochemical Drilling.

2. 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

View Answer

Answer: b [Reason:] Value of diameter produced using Electrochemical drilling, ranges between 1 to 20 mm.

3. 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

View Answer

Answer: c [Reason:] Value of feed rates used in Electrochemical drilling, range between 1 to 5 mm/min.

4. 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

View Answer

Answer: a [Reason:] In ECDR, tubular electrodes are used as cathodic tools for making holes in the materials.

5. 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

View Answer

Answer: c [Reason:] Usually, electrolyte is pumped from centre and exits from side machining gap and vice-versa can also be done in back pressure process.

6. 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

View Answer

Answer: c [Reason:] Material is removed at the frontal gaps and also dissolution takes place at the side machining gaps of the cathodic tool and work piece.

7. 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

View Answer

Answer: b [Reason:] Overcut is the difference between the diameter of hole produced in work piece and the diameter of tool.

8. For high machining accuracy and smaller diametrical oversize, which type of feed rates are required?
a) Very low
b) Low
c) Medium
d) High

View Answer

Answer: d [Reason:] High feed rates are recommended for smaller diametrical oversize and more accuracy.

9. 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

View Answer

Answer: a [Reason:] If we use backward pressure for electrolyte flow, the overcut size decreases.

10. 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

View Answer

Answer: c [Reason:] To reduce overcut size, reverse flow of electrolyte can be used under backward pressure mode, whose value ranges between 0.6 to 2 MPa.

11. What happens to the electrolyte conductivity if the gap increases, in ECDR?
a) Increases
b) Decreases
c) Remains same
d) None of the mentioned

View Answer

Answer: a [Reason:] In ECDR, as the gap increases, the electrical conductivity increases and the dissolution of material increases.

12. Electrolyte back pressure _____ the flow lines on work piece machined using ECDR?
a) Enhances
b) Eliminates
c) Maintains
d) Increases

View Answer

Answer: b [Reason:] Electrolyte back pressure eliminates the flow lines on the machined surfaces which is a major advantages of ECDR.

13. What happens to the roundness error if we use the rotation of ECDR tool?
a) Increases
b) Remains same
c) Decreases
d) Enhances

View Answer

Answer: c [Reason:] Roundness error decreases, if the tool is rotated in ECDR, since it ensures the homogenous flow of electrolyte in the machining gaps.

14. 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

View Answer

Answer: c [Reason:] Sparking, which occur due to very less gap between tool and work piece, which damages both the parts in ECDR.

15. 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

View Answer

Answer: d [Reason:] Current efficiencies less than 100 percent may be related to gas evolution, passive oxide formation, which in turn lead to less dissolution.

Machining Processes MCQ Set 5

1. In advanced machining processes, what is the full form of ECM?
a) Electrochemical manufacturing
b) Electrochemical milling
c) Electrochemical machining
d) Electrochemical masking

View Answer

Answer: b [Reason:] In advanced machining processes, full form of ECM is Electrochemical machining.

2. Of the following scientists, who was the one to introduce first patent on ECM?
a) Balamuth
b) Steve O Flawer
c) Gusseff
d) McGeough

View Answer

Answer: c [Reason:] 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

View Answer

Answer: c [Reason:] 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

View Answer

Answer: b [Reason:] 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

View Answer

Answer: c [Reason:] 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.

6. The system which consists of electrolytic solution and electrodes can be referred as ____.
a) Electrolytic cell
b) Electrode system
c) Electrolytic system
d) Electrode cell

View Answer

Answer: a [Reason:] 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

View Answer

Answer: c [Reason:] 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

View Answer

Answer: a [Reason:] 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 atomic weight
b) Atomic weight to work piece valence
c) Tool valence to molecular weight
d) Molecular weight to tool valence

View Answer

Answer: b [Reason:] Chemical equivalent is the ratio of atomic weight to work piece valence.