This set of Advanced Machining Processes Problems focuses on “LBM-Applications – 2”.
1. Peak power should be increased in Laser drilling process by __________ pulse energy.
a) Increasing
b) Decreasing
c) Reducing
d) Constant
View Answer
Explanation: Required peak power in the laser drilling process can be obtained by increasing the pulse energy while keeping the pulse duration constant.
2. Drilling of holes with larger pulse duration causes which effect to the holes produced?
a) Enlarge holes
b) Reduce hole size
c) Decrease the depth
d) All of the mentioned
View Answer
Explanation: Drilling the holes with larger pulse duration causes enlargement of the hole entrance.
3. What are pulse duration values used for laser drilling?
a) 0.01 to 0.25 ms
b) 0.1 to 2.5 ms
c) 1 to 25 ms
d) 10 to 250 ms
View Answer
Explanation: Value of the duration of the pulse range from 0.1 to 2.5 ms.
4. _________ pulse energy and _________ pulse duration are suitable for drilling.
a) Low, short
b) Low, long
c) High, short
d) High, long
View Answer
Explanation: In LBM, high energy pulses and low pulse duration are more suitable for hole drilling in aerospace materials.
5. Which of the following are the functions of assist gases?
a) Removal of molten material
b) Shield the lenses
c) Better efficiency
d) All of the mentioned
View Answer
Explanation: Assist are used to remove the molten material, it also shield the lenses from expelled material and they are also used for obtaining better process efficiencies.
6. Selection of assist gas depends on which of the following properties of work piece?
a) Material
b) Thickness
c) Material & Thickness
d) None of the mentioned
View Answer
Explanation: The selection of different assist gases depends on the work piece material and its thickness.
7. Which of the following properties of material affect the quality of holes obtained?
a) Reflectivity
b) Absorption coefficient
c) Thermal conductivity
d) All of the mentioned
View Answer
Explanation: Quality of holes depend on reflectivity, absorption coefficient, thermal conductivity, density, specific heat, and latent heat of material.
8. What range of powers are used for cutting through steel?
a) 1 to 20 W
b) 20 to 100 W
c) 200 to 1000 W
d) 1 to 20 kW
View Answer
Explanation: The power ranges from 200 W to 1 kW for cutting through steel.
9. Which gas jet assisted process is suitable for most of the metals?
a) Oxygen gas
b) Nitrogen gas
c) Helium gas
d) All of the mentioned
View Answer
Explanation: Oxygen-jet assistance is used for most metals, as the gas liberates additional energy by the exothermal chemical reactions.
10. What happens to the cutting speed with an increase in the work piece?
a) Increases
b) Decreases
c) Enhances
d) Remains same
View Answer
Explanation: The cutting speed of the process of drilling decreases with an increase in the thickness of the work piece material.
11. What is the full form of LBT in the processes of LBM?
a) Laser Beam Tempering
b) Laser Beam Templating
c) Laser Beam Texturing
d) Laser Beam Tinning
View Answer
Explanation: Full form of LBT is Laser beam texturing which is an application of Laser beam machining.
12. Depth and the crater size depends on which of them below?
a) Energy of beam
b) Dwell time of beam
c) Energy & Dwell time of beam
d) None of the mentioned
View Answer
Explanation: Depth and the crater size depend on the energy and the dwell time of beam.
13. Where are the textured surfaces used that are obtained in LBT?
a) Mould makings
b) Bearings
c) Printer roll manufacturing
d) All of the mentioned
View Answer
Explanation: Textured surfaces obtained in LBT are widely used in mold making, bearings and printer roll manufacturing.
14. The roll is _________ and the laser beam is moved ________ along the roll.
a) Stationary, axially
b) Stationary, perpendicularly
c) Rotated, axially
d) Rotated, perpendicularly
View Answer
Explanation: In texturing process of LBT, the roll is rotated and laser is moved axially along the roll.
15. State whether the following statement is true regarding the texturing in LBT.
“In LBT, hardness of the material is a limitation to the process.”
a) True
b) False
View Answer
Explanation: In Laser beam texturing, hardness of material is not a limitation to the process.
Sanfoundry Global Education & Learning Series – Advanced Machining.
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