This set of Advanced Machining Processes Multiple Choice Questions & Answers (MCQs) focuses on “PBM – MRR, Surface Quality, Applications, Advantages and Disadvantages”.
1. Material removal rates depend on which of the following factors?
a) Work piece material
b) Type of cutting
c) Shielding gases
d) All of the mentioned
View Answer
Explanation: Material removal rates in PBM depend on work piece material, type of cutting and the shielding gas.
2. A low power factors indicates __________ energy required and __________ removal rates.
a) Low, low
b) Low, high
c) High, low
d) High, high
View Answer
Explanation: A low power factor in Plasma beam machining indicates low energy required and high material removal rates.
3. What happens to the machining speed if the thickness of material is increased in PBM?
a) Decreases
b) Increases
c) Enhanced
d) Remains same
View Answer
Explanation: Machining speed in Plasma beam machining reduces with an increase in the thickness of the work piece material.
4. What is the machining speed required for machining of 12mm thick plate with 220 kW energy?
a) 1000 mm/min
b) 1500 mm/min
c) 2000 mm/min
d) 2500mm/min
View Answer
Explanation: Machining speed required for cutting 12-mm thick plate with 220 kW power is about 2500 mm/min.
5. How much distortion is produced while machining using PBM?
a) 10%
b) 20%
c) 30%
d) No distortion is produced
View Answer
Explanation: Heat does not penetrate more than few microns from the edges of the cuts produced by machining using PBM that produce no distortion.
6. The cut edge of the material tends to be __________ than the base metal in PBM.
a) Smoother
b) Harder
c) Same as
d) None of the mentioned
View Answer
Explanation: The cut edge of material in PBM tends to be harder than the base metal.
7. What is the thickness of the HAZ in PBM?
a) 0.001 to 0.23 mm
b) 0.25 to 1.12 mm
c) 1.3 to 2.56 mm
d) 2.73 to 5.26 mm
View Answer
Explanation: The thickness of the HAZ obtained in PBM range from 0.25 to 1.12 mm.
8. How much thickness of cracks may arise beyond HAZ due to rapid cooling?
a) 1.6 mm
b) 2.6 mm
c) 3.6 mm
d) 4.6 mm
View Answer
Explanation: The cracks due to rapid cooling in PBM may extend beyond HAZ to a thickness of 1.6 mm.
9. What are the values of tolerances obtained by using PBM?
a) ± 0.6 mm
b) ± 1.6 mm
c) ± 2.6 mm
d) ± 3.6 mm
View Answer
Explanation: The values of the tolerances obtained by using Plasma beam machining will be about ± 1.6 mm.
10. What is the maximum thickness of the walls of tube machined using plasma arc?
a) 10 mm
b) 30 mm
c) 50 mm
d) 70 mm
View Answer
Explanation: The maximum thickness of the wall tubes that can be produced using PBM is about 50 mm.
11. Which of the following are the advantages of PBM?
a) No chemical
b) Less harmful
c) Operates cleanly
d) All of the mentioned
View Answer
Explanation: Main advantages of Plasma bema machining are no complicated chemical analysis, less harmful and no harmful exposure and it operates cleanly.
12. Which of the following chemicals are used in PBM?
a) Harmful chlorinated fluorocarbons
b) Acid cleaning chemicals
c) Dissolvable solvent chemicals
d) None of the mentioned
View Answer
Explanation: Plasma beam machining uses no harmful chlorinated fluorocarbons, acid cleaning chemicals or any dissolvable solvents.
13. How much amount of energy is required for machining using PBM?
a) Low
b) Moderate
c) High
d) Very high
View Answer
Explanation: The cost for operating the jobs in Plasma beam machining is less and also less energy is required for operating the machine in PBM.
14. What are the disadvantages of PBM?
a) Large power supplies
b) Heat produced
c) Toxic fumes produced
d) All of the mentioned
View Answer
Explanation: Large power for more thick materials, production of heat and toxic fumes are some of the main disadvantages of PBM.
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