McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 351. |
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 |
| Answer» D. all of the mentioned | |
| Explanation: quality of holes depend on reflectivity, absorption coefficient, thermal conductivity, density, specific heat, and latent heat of material. | |
| 352. |
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 |
| Answer» C. 200 to 1000 w | |
| Explanation: the power ranges from 200 w to 1 kw for cutting through steel. | |
| 353. |
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 |
| Answer» A. oxygen gas | |
| Explanation: oxygen-jet assistance is used for most metals, as the gas liberates additional energy by the exothermal chemical reactions. | |
| 354. |
What happens to the cutting speed with an increase in the work piece? |
| A. | increases |
| B. | decreases |
| C. | enhances |
| D. | remains same |
| Answer» B. decreases | |
| Explanation: the cutting speed of the process of drilling decreases with an increase in the thickness of the work piece material. | |
| 355. |
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 |
| Answer» C. laser beam texturing | |
| Explanation: full form of lbt is laser beam texturing which is an application of laser beam machining. | |
| 356. |
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 |
| Answer» C. energy & dwell time of beam | |
| Explanation: depth and the crater size depend on the energy and the dwell time of beam. | |
| 357. |
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 |
| Answer» D. all of the mentioned | |
| Explanation: textured surfaces obtained in lbt are widely used in mold making, bearings and printer roll manufacturing. | |
| 358. |
The roll is and the laser beam is moved along the roll. |
| A. | stationary, axially |
| B. | stationary, perpendicularly |
| C. | rotated, axially |
| D. | rotated, perpendicularly |
| Answer» C. rotated, axially | |
| Explanation: in texturing process of lbt, the roll is rotated and laser is moved axially along the roll. | |
| 359. |
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 |
| Answer» B. false | |
| Explanation: in laser beam texturing, hardness of material is not a limitation to the process | |
| 360. |
Which of the following are the other applications of LBM? |
| A. | dressing of grinding wheels |
| B. | scribing |
| C. | micromachining |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: dressing of grinding wheels, scribing, micromachining, controlled fracturing are some of the other applications of laser beam machining. | |
| 361. |
How the grooves in grinding wheels are produced using laser? |
| A. | evaporation |
| B. | damage of composite |
| C. | evaporation & damage of composite |
| D. | none of the mentioned |
| Answer» C. evaporation & damage of composite | |
| Explanation: grooves on the grinding wheels are produced due to evaporation and damage of the composite wheel material. | |
| 362. |
Work piece tilting depends on which of the following factors? |
| A. | incident power |
| B. | beam speed |
| C. | groove direction |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: work piece tilting depends on the incident power, beam speed, groove direction, and optical absorption coefficient of the material. | |
| 363. |
Lasers of which type are used for modification of electronic components? |
| A. | high power |
| B. | small spot size |
| C. | short pulse length |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: lasers of high power density, small spot size and short pulse length are useful devices for modification of electronic components. | |
| 364. |
Material removal rates which are about mg/pulse produces which type of holes? |
| A. | shallow |
| B. | deep |
| C. | very deep |
| D. | all of the mentioned |
| Answer» A. shallow | |
| Explanation: in lbm, material removal at the rate of milligrams per pulse produces shallow holes in the material. | |
| 365. |
Which of the following materials can be easily separated by laser scribing? |
| A. | silicon |
| B. | glass |
| C. | ceramic |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: brittle materials such as silicon, glass and ceramics may be effectively shaped or separated by laser scribing. | |
| 366. |
Which type of holes can be drilled using Nd-YAG laser? |
| A. | small holes |
| B. | large holes |
| C. | small & large holes |
| D. | none of the mentioned |
| Answer» C. small & large holes | |
| Explanation: nd-yag laser can be used for drilling small holes as well as large holes by trepanning process. | |
| 367. |
Which type of laser can be used for direct drilling or percussion? |
| A. | ruby laser |
| B. | nd-yag laser |
| C. | ruby & nd-yag laser |
| D. | none of the mentioned |
| Answer» C. ruby & nd-yag laser | |
| Explanation: both ruby and nd-yag laser can be used for direct (percussion) drilling purpose. | |
| 368. |
Which of the following lasers is used for cutting thick materials in LBM? |
| A. | co2 + gas assisted |
| B. | co2 only |
| C. | nd-yag |
| D. | ruby |
| Answer» A. co2 + gas assisted | |
| Explanation: co2 + gas assisted laser is used for cutting thicker materials in laser beam machining process. | |
| 369. |
Which of the following lasers is used for slitting of thin metallic materials in LBM? |
| A. | co2 + gas assisted |
| B. | co2 only |
| C. | nd-yag |
| D. | ruby |
| Answer» C. nd-yag | |
| Explanation: nd-yag laser is used for slitting of thin metallic materials in laser beam machining process. | |
| 370. |
Which of the following lasers is used for slitting of thin plastic materials in LBM? |
| A. | co2 + gas assisted |
| B. | co2 only |
| C. | nd-yag |
| D. | ruby |
| Answer» B. co2 only | |
| Explanation: co2 laser is used for slitting of thin plastic materials in laser beam machining process. | |
| 371. |
Which of the following lasers is used for organics and non-metallic materials in LBM? |
| A. | co2 + gas assisted |
| B. | pulsed co2 |
| C. | nd-yag |
| D. | ruby |
| Answer» B. pulsed co2 | |
| Explanation: pulsed co2 laser is used for organics and non-metallic materials in laser beam machining process. | |
| 372. |
Which of the following lasers is used for ceramic materials in LBM? |
| A. | pulsed co2 |
| B. | nd-yag |
| C. | pulsed co2 & nd-yag |
| D. | none of the mentioned |
| Answer» C. pulsed co2 & nd-yag | |
| Explanation: both pulsed co2 and nd-yag lasers can be used for ceramic materials in lbm | |
| 373. |
Which of the following is not an advantage of LBM? |
| A. | rapid machining |
| B. | low operating cost |
| C. | high equipment cost |
| D. | no tool wear |
| Answer» C. high equipment cost | |
| Explanation: rapid machining, low operating cost and no tool wear are some of the advantages of laser beam machining. | |
| 374. |
Which of the following systems is used for locating the hole accurately for alignment? |
| A. | mechanical control system |
| B. | optical laser system |
| C. | measurement system |
| D. | alignment system |
| Answer» B. optical laser system | |
| Explanation: holes can be accurately located using optical laser system for alignment in laser beam machining. | |
| 375. |
Very holes with a aspect ratio can be produced using Laser beam machining. |
| A. | small, small |
| B. | small, large |
| C. | large, small |
| D. | large, large |
| Answer» B. small, large | |
| Explanation: in laser beam machining, very small holes with large aspect ratios can be produced. | |
| 376. |
How are the machining times in Laser beam machining? |
| A. | very slow machining times |
| B. | slow machining times |
| C. | moderate machining times |
| D. | fast machining times |
| Answer» D. fast machining times | |
| Explanation: machining is very much rapid and the setup times are economical in laser beam machining. | |
| 377. |
How is the operating cost of the machines used in Laser beam machining? |
| A. | low |
| B. | moderate |
| C. | high |
| D. | very high |
| Answer» A. low | |
| Explanation: the operating cost of the machines in lbm is low but the equipment cost itself is of high cost. | |
| 378. |
How much amount of tapers are occurred in Laser drilled holes? |
| A. | no taper |
| B. | negligible amount of taper |
| C. | some amount |
| D. | none of the mentioned |
| Answer» C. some amount | |
| Explanation: tapers are generally occurred in the direct drilling of holes using laser beam machining. | |
| 379. |
State whether the following statement regarding Laser beam machining is true or false. “In LBM, a blind hole of precise depth is easy to achieve.” |
| A. | true |
| B. | false |
| Answer» B. false | |
| Explanation: a blind hole of precise is difficult to achieve in laser beam machining. | |
| 380. |
What is the maximum depth up to which holes can be drilled using LBM? |
| A. | 10 mm |
| B. | 30 mm |
| C. | 50 mm |
| D. | 70 mm |
| Answer» C. 50 mm | |
| Explanation: the thickness of the material that can be laser drilled is restricted to 50 mm. | |
| 381. |
What is to be done to the adherent material which are found at exit holes? |
| A. | shape them |
| B. | leave away |
| C. | remove them |
| D. | flatten them view answer |
| Answer» C. remove them | |
| Explanation: adherent material found at the exit of holes has to be removed in lbm | |
| 382. |
What is the full form of PBM in the advanced machining processes? |
| A. | plasma beam manufacturing |
| B. | plasma beam machining |
| C. | plasma blast manufacturing |
| D. | plasma blast machining |
| Answer» B. plasma beam machining | |
| Explanation: the full form of pbm in the advanced machining processes is plasma beam machining. | |
| 383. |
PBM is the only process which works faster in steel than steel. |
| A. | stainless, mild |
| B. | mild, stainless |
| C. | remains same all |
| D. | all of the mentioned |
| Answer» A. stainless, mild | |
| Explanation: pbm is the only fabrication process which works faster in stainless steels compared to mild steels. | |
| 384. |
What is the value of velocity of plasma jet in Plasma beam machining? |
| A. | 100 m/sec |
| B. | 300 m/sec |
| C. | 400 m/sec |
| D. | 500 m/sec |
| Answer» D. 500 m/sec | |
| Explanation: the value of the velocity of the plasma jet in plasma beam machining is about 500 m/sec. | |
| 385. |
What is the value of material removal rate in Plasma Beam Machining process? |
| A. | 50 cm3/min |
| B. | 100 cm3/min |
| C. | 150 cm3/min |
| D. | 200 cm3/min |
| Answer» C. 150 cm3/min | |
| Explanation: the values of the material removal rates in plasma beam machining will be nearly 150 cm3/min. | |
| 386. |
What is the value of specific energy used in Plasma beam machining process? |
| A. | 100 w/(cm3-min) |
| B. | 200 w/(cm3-min) |
| C. | 300 w/(cm3-min) |
| D. | 400 w/(cm3-min) |
| Answer» A. 100 w/(cm3-min) | |
| Explanation: the value of the specific energy used in plasma beam machining process is about 100 w/(cm3-min). | |
| 387. |
What is the value of the current used in PBM process? |
| A. | up to 200 a |
| B. | up to 400 a |
| C. | up to 600 a |
| D. | up to 800 a |
| Answer» C. up to 600 a | |
| Explanation: the value of the current used in pbm will be up to 600 a. | |
| 388. |
What is the maximum value of the thickness used in PBM process? |
| A. | 100 mm |
| B. | 200 mm |
| C. | 300 mm |
| D. | 400 mm |
| Answer» B. 200 mm | |
| Explanation: the maximum value of the thickness used in the plasma beam machining process is about 200 mm. | |
| 389. |
Which of the following are the different shielded plasmas used in PBM? |
| A. | gas-shielded plasma |
| B. | water-shielded plasma |
| C. | gas-shielded & water-shielded plasma |
| D. | none of the mentioned |
| Answer» C. gas-shielded & water-shielded plasma | |
| Explanation: both gas-shielded plasma and water shielded plasma are used in the plasma beam machining process | |
| 390. |
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 |
| Answer» D. all of the mentioned | |
| Explanation: material removal rates in pbm depend on work piece material, type of cutting and the shielding gas. | |
| 391. |
A low power factors indicates energy required and removal rates. |
| A. | low, low |
| B. | low, high |
| C. | high, low |
| D. | high, high |
| Answer» B. low, high | |
| Explanation: a low power factor in plasma beam machining indicates low energy required and high material removal rates. | |
| 392. |
What happens to the machining speed if the thickness of material is increased in PBM? |
| A. | decreases |
| B. | increases |
| C. | enhanced |
| D. | remains same |
| Answer» A. decreases | |
| Explanation: machining speed in plasma beam machining reduces with an increase in the thickness of the work piece material. | |
| 393. |
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 |
| Answer» D. 2500mm/min | |
| Explanation: machining speed required for cutting 12-mm thick plate with 220 kw power is about 2500 mm/min. | |
| 394. |
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 |
| Answer» B. harder | |
| Explanation: the cut edge of material in pbm tends to be harder than the base metal. | |
| 395. |
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 |
| Answer» A. 1.6 mm | |
| Explanation: the cracks due to rapid cooling in pbm may extend beyond haz to a thickness of 1.6 mm. | |
| 396. |
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 |
| Answer» B. ± 1.6 mm | |
| Explanation: the values of the tolerances obtained by using plasma beam machining will be about ± 1.6 mm. | |
| 397. |
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 |
| Answer» C. 50 mm | |
| Explanation: the maximum thickness of the wall tubes that can be produced using pbm is about 50 mm. | |
| 398. |
Which of the following are the advantages of PBM? |
| A. | no chemical |
| B. | less harmful |
| C. | operates cleanly |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: main advantages of plasma bema machining are no complicated chemical analysis, less harmful and no harmful exposure and it operates cleanly. | |
| 399. |
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 |
| Answer» D. none of the mentioned | |
| Explanation: plasma beam machining uses no harmful chlorinated fluorocarbons, acid cleaning chemicals or any dissolvable solvents. | |
| 400. |
How much amount of energy is required for machining using PBM? |
| A. | low |
| B. | moderate |
| C. | high |
| D. | very high |
| Answer» A. low | |
| 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. | |
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