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Machining Processes MCQ Set 1

1. If there is a change in the selected machining conditions, it will have impact on which of the following?
a) Process accuracy
b) Surface finish
c) All of the mentioned
d) None of the mentioned

View Answer

Answer: c [Reason:] Selected machining conditions should remain unchanged, because, it will have a direct impact on accuracy and surface finish.

2. Surface roughness depends on current density, which is affected by which of the following?
a) Tool feed rate
b) Gap voltage
c) Work piece material
d) All of the mentioned

View Answer

Answer: d [Reason:] Roughness depend on current density, which is affected by tool feed rate, gap voltage, work material, pH number, temperature, conductivity and pressure.

3. Machining conditions leading to high accuracy are associated with ____ surface roughness and ____ productivity.
a) Greater, greater
b) Smaller, greater
c) Greater, smaller
d) Smaller, smaller

View Answer

Answer: b [Reason:] Accuracy is associated with smaller surface roughness and greater machining productivity.

4. Non stationary behaviour of ECM is due to, which of the factors below?
a) Gas generation
b) Heating
c) Passivation
d) All of the mentioned

View Answer

Answer: d [Reason:] Non stationary behaviour of ECM is due to the inter electrode gap conditions such as gas generation, passivation, heating and other electrode reactions.

5. For large components, actual machining time constitutes to how much percentage of the total machining time?
a) Very low
b) Low
c) Medium
d) High

View Answer

Answer: d [Reason:] Actual machining time of large components constitutes to a high percentage of total machining time.

6. What happens to the product cycle time, if the machining performance is improved?
a) Increases
b) Decreases
c) Remains same
d) None of the mentioned

View Answer

Answer: b [Reason:] As the machining performance is improved, the time take for a product to complete its production cycle, decreases.

7. The cost of additional control hardware remain a _____ fraction of total machining cost.
a) Small
b) Large
c) Equal
d) None of the mentioned

View Answer

Answer: a [Reason:] Cost of additional control hardware is very less, which constitutes to a small fraction in total machining cost.

8. With an increase in unmanned machining hours, what happens to the efficiency of ECM?
a) Increases
b) Reduces
c) Decreases
d) Increase and then decrease

View Answer

Answer: a [Reason:] Increase in unmanned machining hours lead to a raise in efficiency of ECM.

9. State whether following statement is true or false regarding the process control of ECM.
“In Electrochemical machining, increase in unmanned machining hours reduces the possibility of integration of process with CAD/CAM systems.”
a) True
b) False

View Answer

Answer: b [Reason:] An increase in unmanned machining hours, enhances the process integration with CAD/CAM systems.

10. Which type of damage is caused by deterioration which is caused by spark?
a) Reparable
b) Irreparable
c) All of the mentioned
d) None of the mentioned

View Answer

Answer: b [Reason:] Deterioration by sparking may cause irreparable damage to the work pieces.

Machining Processes MCQ Set 2

1. Which of the following shapes can be produced using Electro discharge machining?
a) Complex shapes
b) Simple shapes
c) All of the mentioned
d) None of the mentioned

View Answer

Answer: c [Reason:] Electro discharge machining is used to machine complex shapes to a high degree of accuracy.

2. Which of the following materials can be machined using Electro discharge machining?
a) Heat resistant alloys
b) Super alloys
c) Carbides
d) All of the mentioned

View Answer

Answer: d [Reason:] EDM is used to machine materials such as carbides, heat resistant and super alloys which are difficult-to-machine materials.

3. Which of the following are the applications of Electro discharge machining?
a) Holes
b) Slots
c) Texturing
d) All of the mentioned

View Answer

Answer: d [Reason:] Micromachining of holes, slots, dies, texturing, milling, surface modification and mechanical pulsing are some typical applications of Electro discharge machining.

4. State whether following statement is true or false regarding the applications of EDM.
“In advanced machining processes, the incorporation of EDM with CIM increased the length of time for unit operation.”
a) True
b) False

View Answer

Answer: b [Reason:] The incorporation of EDM in CIM reduced the length of time per unit operation.

5. Which type of electrode is used for drilling in Electro discharge machining?
a) Flat electrode
b) Cuboidal electrode
c) Tubular electrode
d) Spherical electrode

View Answer

Answer: c [Reason:] Tubular electrode is mostly preferred in Electro discharge machining, for drilling purpose.

6. The dielectric fluid is flushed in thorough which part of the electrode in drilling in EDM?
a) Interior hole
b) Side gaps
c) All of the mentioned
d) None of the mentioned

View Answer

Answer: a [Reason:] EDM drilling uses a tubular electrode which flushes the dielectric thorough the interior holes for removing debris.

7. Which type of holes can be produced through drilling using Electro discharge machining?
a) Irregular
b) Curved
c) Tapered
d) All of the mentioned

View Answer

Answer: d [Reason:] Drilling of work piece using EDM produced holes which can be irregular, curved, tapered as well as inclined holes.

8. What are the values of general feed rates used for drilling in EDM?
a) 0.1 mm/min
b) 0.3 m/min
c) 0.5 mm/min
d) 0.7 mm/min

View Answer

Answer: a [Reason:] Usually a feed rate of 0.10 mm/min is used for drilling the work piece using Electro discharge machining.

9. What are range of diameter values obtained by drilling using EDM?
a) 0.01 to 0.05 mm
b) 0.1 to 0.5 mm
c) 1 to 5 mm
d) 10 to 15 mm

View Answer

Answer: b [Reason:] Diameter values while drilled using Electro discharge machining, ranges from 0.10 to 0.50 mm.

10. What are the values of overcuts left behind after drilling of work piece?
a) 0.01 to 0.05 mm
b) 0.1 to 0.5 mm
c) 1 to 5 mm
d) 10 to 15 mm

View Answer

Answer: a [Reason:] Overcut values from 0.01 to 0.05 mm are obtained after the drilling process in EDM.

11. Electro discharge sawing is an application of EDM which employs _____ as tool material.
a) Steel band
b) Disc
c) All of the mentioned
d) None of the mentioned

View Answer

Answer: c [Reason:] Electro discharge sawing is an application of EDM which employs either steel band or disc as tool.

12. When compared to the conventional abrasive sawing, how many times faster is the MRR?
a) Twice
b) Thrice
c) Four
d) Five

View Answer

Answer: a [Reason:] Electro discharge sawing cuts the work piece material at the rates which are twice that of conventional abrasive sawing method.

13. How much amount of burr is produce while machined using Electro discharge sawing?
a) 10%
b) 20%
c) 50%
d) No Burr

View Answer

Answer: d [Reason:] The cuts produced in Electro discharge sawing have smaller kerf widths which hav no burrs in it.

14. What are the values of finish obtained by machining work piece thorough Electro discharge sawing?
a) 0.1 to 4 µm
b) 6.3 to 10 µm
c) 12.4 to 23 µm
d) 25.6 to 40 µm

View Answer

Answer: b [Reason:] The finish obtained ranges from 6.3 to 10 µm when machined using Electro discharge sawing.

15. What are the recast layer thickness values obtained in ED sawing?
a) 0.001 to 0.022 mm
b) 0.025 to 0.130 mm
c) 0.236 to 0.352 mm
d) 0.432 to 0.568 mm

View Answer

Answer: b [Reason:] The recast layer thickness values obtained from ED sawing range from 0.025 to 0.13 mm.

Machining Processes MCQ Set 3

1. What are the values of temperatures obtained in Electro discharge machining?
a) 1000 to 2000 oC
b) 2000 to 4000 oC
c) 4000 to 8000 oC
d) 8000 to 12000 oC

View Answer

Answer: d [Reason:] The temperature attained while machining in Electro discharge machining are from 8000 to 12000 oC.

2. What is the value of thickness of recast layer obtained when power of 5 µJ is given?
a) 1 µm
b) 3 µm
c) 5 µm
d) 7 µm

View Answer

Answer: a [Reason:] When a power of 5 µJ is given, recast layer thickness of 1 µm is obtained.

3. What are the values of thickness of recast layers in Electro discharge machining?
a) 0.001 to 0.025 µm
b) 0.01 to 0.25 µm
c) 1 to 25 µm
d) 10 to 250 µm

View Answer

Answer: c [Reason:] In Electro discharge machining, the value of thickness of recast layers ranges from 1 to 25 µm.

4. In Electro discharge machining, some annealing of the work piece can be expected _____ the machined surface.
a) On
b) Just below
c) Above
d) At bottom

View Answer

Answer: b [Reason:] Annealing of some part of the work piece in EDM can be expected just below the machined surface.

5. The depth of the annealed surface is _____ to the amount of power used in machining operation.
a) Directly proportional
b) Inversely proportional
c) Exponential
d) All of the mentioned

View Answer

Answer: a [Reason:] The depth of annealed surface in EDM is proportional to the amount of power used.

6. What are the values of thickness of annealed surface obtained while machining using EDM?
a) 1 to 25 µm
b) 50 to 200 µm
c) 200 to 500 µm
d) 500 to 1000 µm

View Answer

Answer: b [Reason:] Values of annealed surface thickness range from 50 µm to 200 µm.

7. In EDM, choosing electrodes that produce which type of machining reduces the annealing effect?
a) Stable
b) Unstable
c) Uneven
d) All of the mentioned

View Answer

Answer: a [Reason:] In Electro discharge machining, choosing the electrodes which produce more stable machining reduces the annealing effect.

8. What happens to the fatigue strength of alloys if altered surfaces are produced in Electro discharge machining?
a) Increases
b) Reduces
c) Enhances
d) Improves

View Answer

Answer: b [Reason:] The altered surface layers that are produced in Electro discharge machining, significantly reduces the fatigue strength of alloys.

9. The altered layers formed during the process of EDM consists of which of the following?
a) Tempered layers
b) Heat affected zones
c) Intergranular precipitates
d) All of the mentioned

View Answer

Answer: d [Reason:] Altered layers consists of recast layers, tempered layers, HAZs and intergranular precipitates in EDM.

10. During roughing process through Electro discharge machining, what is the thickness of layer formed?
a) <0.075 mm
b) <0.125 mm
c) <0.500 mm
d) <0.750 mm

View Answer

Answer: b [Reason:] The thickness of layer obtained after machining is <0.127 mm in EDM.

11. During finishing process through Electro discharge machining, what is the value thickness of layer formed?
a) <0.075 mm
b) <0.125 mm
c) <0.500 mm
d) <0.750 mm

View Answer

Answer: a [Reason:] The thickness of layer obtained during EDM finishing is <0.075 mm.

12. Which of the following processes can be used for restoration of fatigue properties?
a) Low-stress grinding
b) Chemical machining
c) Reheat treatment
d) All of the mentioned

View Answer

Answer: d [Reason:] For removal of altered layers processes such as low-stress grinding, chemical machining, reheat treatment, metallurgical type coating and application of shot peening.

13. State whether following statement is true or false regarding the HAZ in EDM.
“In EDM, post treatment to recover fatigue strength is not recommended.”
a) True
b) False

View Answer

Answer: b [Reason:] After machining using EDM, post treatment to restore the fatigue strength is recommended.

Machining Processes MCQ Set 4

1. Metal is removed on which of the components in electro discharge machining?
a) Electrode tool
b) Work piece
c) All of the mentioned
d) None of the mentioned

View Answer

Answer: c [Reason:] In Electro discharge machining, material is removed from both tool and work piece.

2. On which of the following components, does the MRR depend?
a) Work piece
b) Electrode Tool
c) All of the mentioned
d) None of the mentioned

View Answer

Answer: c [Reason:] Material removal rate not only depends on work piece material but also the tool material.

3. Of the following, which factors influence the material removal rate?
a) Pulse condition
b) Electrode polarity
c) Machining medium
d) All of the mentioned

View Answer

Answer: d [Reason:] The factors such as pulse conditions, electrode polarity and machining medium also affect the material removal rate.

4. In Electro discharge machining, materials with low melting point have which type of material removal rate?
a) Very low
b) Low
c) Medium
d) High

View Answer

Answer: d [Reason:] In Electro discharge machining, materials having low melting point have high material removal rates and vice-versa.

5. In Electro discharge machining, materials with low melting point have which type of surface roughness?
a) Rough
b) smooth
c) Fine
d) All of the mentioned

View Answer

Answer: a [Reason:] In Electro discharge machining, materials having low melting point have high rougher surfaces and vice-versa.

6. What are the values of material removal rates in EDM?
a) 0.001 to 0.1 mm3/min
b) 0.1 to 400 mm3/min
c) 400 to 1000 mm3/min
d) 1000 to 5000 mm3/min

View Answer

Answer: b [Reason:] In EDM, material removal rates range from 0.10 to 400 mm3/min.

7. What happens to the material removal rate if the sparks are very less in EDM?
a) Decreases
b) Increases
c) Increase and then decrease
d) All of the mentioned

View Answer

Answer: a [Reason:] In EDM, if sparks generated are less then material removal rate decreases.

8. What is the relation between the melting point and the material removal rate?
a) Directly Proportional
b) Inversely proportional
c) Indirectly proportional
d) None of the mentioned

View Answer

Answer: b [Reason:] In Electro discharge machining, material removal rate is inversely proportional to the melting point.

9. What happens to the crater size if we increase the current keeping the pulse time constant?
a) Increase
b) Decrease
c) Decrease and increase
d) None of the mentioned

View Answer

Answer: a [Reason:] By keeping pulse time constant and increasing current, crater size also increases.

10. What happens to the crater size if we decrease the pulse time keeping the current constant?
a) Increase
b) Decrease
c) Increase and decrease
d) None of the mentioned

View Answer

Answer: b [Reason:] By decreasing pulse time and keeping current constant, crater size also decreases.

Machining Processes MCQ Set 5

1. What is the value of order of frequency applied between the two electrodes in EDM?
a) 1 kHz
b) 3 kHz
c) 5 kHz
d) 7 kHz

View Answer

Answer: c [Reason:] The magnitude of frequency applied between the electrodes in EDM is about 5 kHz.

2. What are the magnitude of voltages used in Electro discharge machining?
a) 1 to 20 V
b) 20 to 120 V
c) 120 to 220 V
d) 220 to 320 V

View Answer

Answer: b [Reason:] In EDM, the magnitude of voltages range between 20 and 120 V.

3. What are the values of gaps between the electrodes in EDM?
a) 0.001 – 0.05 mm
b) 0.01 – 0.5 mm
c) 0.1 – 5 mm
d) 1 – 15 mm

View Answer

Answer: b [Reason:] In EDM, very small gaps that range between 0.01 – 0.5 mm are maintained.

4. How is material removed in Electro discharge machining?
a) Melt and evaporate
b) Corrode and break
c) Mechanical erosion takes place
d) None of the mentioned

View Answer

Answer: a [Reason:] In Electro discharge machining, material is melted and then evaporated.

5. What is the radius of channel, when electrical breakdown occur?
a) 4 µm
b) 6 µm
c) 8 µm
d) 10 µm

View Answer

Answer: d [Reason:] In EDM, the electrical breakdown occurs in dielectric in a channel of radius about 10 µm.

6. State whether following statement is true or false regarding EDM.
“In EDM, negative ions (electrons) collide with positive ions to generate heat.”
a) True
b) False

View Answer

Answer: b [Reason:] In Electro discharge machining, electrons collide with neutral atoms producing positive ions and further electrons.

7. What are the values of temperature that are obtained while machining using EDM?
a) 2000 to 3000ᵒC
b) 4000 to 6000ᵒC
c) 8000 to 12000ᵒC
d) 15000 to 20000ᵒC

View Answer

Answer: c [Reason:] The temperatures obtained when the ions reach their respective electrodes, range between 8000ᵒC and 12000ᵒC.

8. What range of heat fluxes are obtained while machining using EDM?
a) 1017 W/m2
b) 1019 W/m2
c) 1024 W/m2
d) 1027 W/m2

View Answer

Answer: a [Reason:] Heat flux up to the value of 1017 W/m2 are obtained in EDM.

9. What is the duration of sparks that are produced in Electro discharge machining?
a) 0.001 – 1 µs
b) 0.1 – 2000 µs
c) 0.2 – 100 ms
d) 100 – 2000 ms

View Answer

Answer: b [Reason:] Duration of spark in Electro discharge machining is about 0.1 to 2000 µs.

10. State whether following statement is true or false about material removal in EDM.
“In EDM, high pressures allow the metal to evaporate.”
a) True
b) False

View Answer

Answer: b [Reason:] High pressures in EDM try to prevent the super-heated metal from evaporation.

11. What are the values of pressure of the plasma in EDM?
a) Up to 2 atm
b) Up to 20 atm
c) Up to 200 atm
d) Up to 2000 atm

View Answer

Answer: c [Reason:] Pressure on the plasma channel rises to values as high as 200 atm when dielectric evaporates.

12. At the end of pulse, super-heated metal evaporates _____.
a) Explosively
b) Normally
c) Periodically
d) Occasionally

View Answer

Answer: a [Reason:] At the end of pulse, pressure drops suddenly and super-heated metal evaporates explosively.

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