McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 251. |
Texturing is applied to the steel sheets at which stages of cold rolling? |
| A. | initial stages |
| B. | middle stages |
| C. | final stages |
| D. | all of the mentioned |
| Answer» A. initial stages | |
| Explanation: at the final stages of cold rolling, texturing is applied to the steel sheets. | |
| 252. |
What is the full form of EDT in EDM processes? |
| A. | electro discharge tinplating |
| B. | electro discharge texturing |
| C. | electro discharge tapping |
| D. | electro discharge turing |
| Answer» B. electro discharge texturing | |
| Explanation: electro discharge texturing is a variant of edm which is the full form of edt. | |
| 253. |
Which of the following are the process variables for texturing process in EDM? |
| A. | pulse current |
| B. | electrode polarity |
| C. | dielectric type |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: pulse current, polarity, dielectric, electrode material and roll rotation speed are some process variables of texturing. | |
| 254. |
What are the values of current amplitudes used in EDT? |
| A. | 0.2 to 1 a |
| B. | 2 to 10 a |
| C. | 20 to 100 a |
| D. | 40 to 200 a |
| Answer» B. 2 to 10 a | |
| Explanation: the values of current amplitudes in edt range from 2 to 10 a. | |
| 255. |
What are duration values of current amplitude in EDT? |
| A. | 0.1 to 1 µs |
| B. | 1 to 10 µs |
| C. | 10 to 100 µs |
| D. | 100 to 1000 µs |
| Answer» C. 10 to 100 µs | |
| Explanation: duration of current amplitudes used for edt range from 10 to 100 µs. | |
| 256. |
What are the spindle rotation speeds used in EDT? |
| A. | 1 to 4 rpm |
| B. | 10 to 40 rpm |
| C. | 20 to 60 rpm |
| D. | 30 to 90 rpm |
| Answer» B. 10 to 40 rpm | |
| Explanation: spindle rotation speeds for edt process range from 10 to 40 rpm. | |
| 257. |
What happens to the machine capital cost in EDT when there is an increase in tool quantity? |
| A. | decreases |
| B. | increases |
| C. | remains same |
| D. | none of the mentioned |
| Answer» B. increases | |
| Explanation: with increase in tools quantity machine cost increases but texturing cost reduces. | |
| 258. |
What is the value of depth to diameter ratio in Micro-Electro discharge machining process? |
| A. | 10:1 |
| B. | 5:2 |
| C. | 4:3 |
| D. | 2:1 |
| Answer» A. 10:1 | |
| Explanation: value of the depth to diameter ratio in micro-electro discharge machining is about 10:1. | |
| 259. |
What are the values of depths that can be machined using Micro-EDM? |
| A. | 1 mm |
| B. | 10 mm |
| C. | 100 mm |
| D. | 1000 mm |
| Answer» C. 100 mm | |
| Explanation: micro-electro discharge machining can machine up to a depth of 100 mm in the work piece material. | |
| 260. |
What are the machining rates used in Micro-EDM process? |
| A. | 0.1 to 2 mm/min |
| B. | 1 to 20 mm/min |
| C. | 10 to 200 mm/min |
| D. | 100 to 500 mm/min |
| Answer» B. 1 to 20 mm/min | |
| Explanation: machining rates used in micro-edm process range from 1 to 20 mm/min. | |
| 261. |
What are the values of hole diameters obtained using Wire electro discharge grinding? |
| A. | 1 µm |
| B. | 3 µm |
| C. | 5 µm |
| D. | 7 µm |
| Answer» C. 5 µm | |
| Explanation: values of hole diameters up to 5 µm can be obtained using wire electro discharge grinding process. | |
| 262. |
What are the feed rates used in WEDG process? |
| A. | 1 to 5 mm/min |
| B. | 5 to 10 mm/min |
| C. | 10 to 15 mm/min |
| D. | 15 to 20 mm/min |
| Answer» B. 5 to 10 mm/min | |
| Explanation: feed rate values in wedg process range from 5 to 10 mm/min | |
| 263. |
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 |
| Answer» B. abnormal discharges | |
| Explanation: avoidance of abnormal discharges has become a major difficulty in electro discharge machining process. | |
| 264. |
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 |
| Answer» A. increased | |
| Explanation: the off time of pulse is increased in order to avoid the abnormal electric discharges. | |
| 265. |
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 |
| Answer» A. pulse duration and current | |
| Explanation: inputs used are pulse duration and current in a simple application. | |
| 266. |
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 |
| Answer» A. pulse duration and current | |
| Explanation: outputs used are normal and abnormal pulses in a simple application. | |
| 267. |
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 |
| Answer» D. all of the mentioned | |
| Explanation: machining depth, surface roughness, accuracy are correlated with the machining conditions at the output stage. | |
| 268. |
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 |
| Answer» A. slower rate | |
| Explanation: edm’s levels of computer integration is at a slower rate when compared to conventional machining processes. | |
| 269. |
Manufacturing of tool electrode undergoes which of the following processes? |
| A. | milling |
| B. | turning |
| C. | finishing |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: the tool electrode manufacturing used in edm has to undergo the basic production processes such as milling, turning and finishing. | |
| 270. |
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 |
| Answer» D. all of the mentioned | |
| Explanation: the temperatures in the working gap increases leading to hazardous smoke, vapours and aerosols. | |
| 271. |
Hydro carbons present in the dielectric fluid have impact on which of the body parts? |
| A. | eyes |
| B. | teeth |
| C. | skin |
| D. | nails |
| Answer» C. skin | |
| Explanation: hydrocarbons present in dielectric fluids of edm will have a negative impact on the skin in our body. | |
| 272. |
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 |
| Answer» B. explosion may occur | |
| Explanation: explosion occurs if electro discharge machining is done under unfavourable process variables and conditions. | |
| 273. |
Reduction in the electrical energy consumption will have impact on which aspects mentioned below? |
| A. | environmental |
| B. | economic |
| C. | environmental & economic |
| D. | none of the mentioned |
| Answer» C. environmental & economic | |
| Explanation: the reduction of electric energy consumption has economic as well as environmental benefits | |
| 274. |
A thin metallic wire used in wire-cut EDM is kept submerged in a tank of |
| A. | dielectric fluid |
| B. | pure water |
| C. | molten metal |
| D. | kerosene |
| Answer» A. dielectric fluid | |
| Explanation: the wire electric discharge machining (wedm) is a variation of edm and is commonly known as wire-cut edm or wire cutting. in this process, a thin metallic wire is fed onto the workpiece, which is submerged in a tank of dielectric fluid such as deionized water. | |
| 275. |
Wire-cut EDM can cut plates of thickness upto |
| A. | 50mm |
| B. | 100mm |
| C. | 300mm |
| D. | 500mm |
| Answer» C. 300mm | |
| Explanation: wire-cut edm process can cut plates as thick as 300mm and is used for | |
| 276. |
In WEDM, the wire is held tight between |
| A. | upper and lower nozzles |
| B. | upper and lower diamond guides |
| C. | upper and lower groves in the handle |
| D. | upper and lower pulleys |
| Answer» B. upper and lower diamond guides | |
| Explanation: in wire-cut edm (wedm), the wire which is constantly fed from a spool, is held between upper and lower diamond guides. the guides are usually cnc-controlled and move in the x–y plane. | |
| 277. |
The upper guide can move independently about |
| A. | x-axis |
| B. | y-axis |
| C. | x-y-w axes |
| D. | z-u-v axes |
| Answer» D. z-u-v axes | |
| Explanation: on most machines, the upper guide can move independently about the z–u–v axes, giving it the flexibility to cut tapered and transitioning shapes (example: square at the bottom and circle on the top). | |
| 278. |
In the wire-cut EDM process, de-ionizing units are used for controlling the |
| A. | feed rate |
| B. | resistivity |
| C. | burr formation |
| D. | temperature of the wire |
| Answer» B. resistivity | |
| Explanation: in the wire-cut edm process, water is commonly used as the dielectric fluid. filters and de-ionizing units are used for controlling the resistivity and other electrical properties. | |
| 279. |
In the wire-cut EDM process, water is also used for |
| A. | cooling |
| B. | increasing the feed rate |
| C. | flushing away the burr |
| D. | controlling the cutting speed |
| Answer» C. flushing away the burr | |
| Explanation: apart from being used as a dielectric fluid, the water also helps in flushing away the debris from the cutting zone. the flushing also helps to determine the feed rates to be given for different thickness of the materials. | |
| 280. |
The WEDM process requires |
| A. | lower initial investment |
| B. | lesser cutting forces |
| C. | a skilled operator |
| D. | a coolant pump |
| Answer» B. lesser cutting forces | |
| Explanation: the wire-cut edm process requires lesser cutting forces in material removal; hence it is generally used when lower residual stresses in the workpiece are desired. | |
| 281. |
The materials which are not stress-relieved before machining by WEDM process can get distorted during machining. |
| A. | true |
| B. | false |
| Answer» A. true | |
| Explanation: if the energy/power pulse is relatively low (as in finishing operations), little changes in the mechanical properties of the material are expected due to residual stresses. the components which are not stress-relieved earlier can get distorted in the machining process. | |
| 282. |
During the WEDM process, workpiece undergoes a number of thermal cycles. |
| A. | true |
| B. | false |
| Answer» A. true | |
| Explanation: in wedm process, the selection of process parameters is very crucial, as in some cases the workpiece undergoes significant thermal cycles the can be very severe. these thermal cycles can form recast layers and induce residual tensile stresses on the workpiece. | |
| 283. |
Electrically conductive materials are cut by WEDM process by mechanism. |
| A. | thermal |
| B. | electro-thermal |
| C. | electro-dynamic |
| D. | fused metal |
| Answer» B. electro-thermal | |
| Explanation: electrically conductive materials are cut by wedm process by an electro- thermal mechanism. in the wedm process, the motion of the wire is slow. it is fed in the programmed path and material is removed from the workpiece accordingly | |
| 284. |
In wire-cut EDM process, material removal takes place by a series of discrete discharges between |
| A. | di-electric fluid and the wire electrode |
| B. | the wire-electrode and the workpiece |
| C. | the workpiece and the cnc-table |
| D. | wire electrodes |
| Answer» B. the wire-electrode and the workpiece | |
| Explanation: in wire-cut edm process, material removal takes place by a series of discrete discharges between the wire and the workpiece in the presence of a di-electric fluid. water is commonly used as the di-electric fluid. | |
| 285. |
The di-electric fluid gets ionizes in between gap. |
| A. | tool-electrode |
| B. | cathode-anode |
| C. | workpiece-electrode |
| D. | tool-workpiece |
| Answer» A. tool-electrode | |
| Explanation: the di-electric fluid gets ionized in between the tool-electrode gap and hence, helps in creating a path for each discharge. because of these discharges, material is removed from the workpiece. | |
| 286. |
The burr or cut particles are flushed away by the |
| A. | electrode |
| B. | motion of the workpiece |
| C. | di-electric fluid |
| D. | coolant |
| Answer» C. di-electric fluid | |
| Explanation: the area wherein discharge takes place gets heated to very high temperatures such that the surface gets melted and removed. the cut particles (debris) get flushed away by the continuously flowing dielectric fluid. | |
| 287. |
Wire-cut EDM (WEDM) process is widely used for |
| A. | alloy steels |
| B. | tool steels |
| C. | stainless steels |
| D. | carbon steels |
| Answer» B. tool steels | |
| Explanation: wedm is a non-conventional process and is very widely used in tool steels for a pattern and die making industries. the process is also used for cutting intricate shapes in components used for the electric and aerospace industries. | |
| 288. |
For which of the following materials wire-cut EDM is not used? |
| A. | aluminium |
| B. | zirconium |
| C. | steels |
| D. | titanium |
| Answer» B. zirconium | |
| Explanation: wire-cut edm is used for cutting: | |
| 289. |
WEDM process can be used for cutting hard extrusion dies. |
| A. | true |
| B. | false |
| Answer» A. true | |
| Explanation: this process is used in the following areas: | |
| 290. |
WEDM process can be used for manufacturing of micro-tools. |
| A. | true |
| B. | false |
| Answer» A. true | |
| Explanation: following are the few areas where wedm process is used: | |
| 291. |
How many subsystems are there in wire-cut EDM process? |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | 5 |
| Answer» C. 4 | |
| Explanation: the subsystems of wire-edm process are: | |
| 292. |
Di-electric system used in WEDM process is similar to that of the process. |
| A. | conventional drilling |
| B. | conventional milling |
| C. | conventional edm |
| D. | broaching |
| Answer» C. conventional edm | |
| Explanation: the power supply and the di-electric system used in wedm is very similar to that of the conventional edm. the main difference lies only in the type of di-electric used. | |
| 293. |
In wire-cut EDM, a moving wire is used to |
| A. | remove the burr |
| B. | cut complex outlines |
| C. | melt the material |
| D. | make the way for the di-electric fluid |
| Answer» B. cut complex outlines | |
| Explanation: in wire-cut edm, a moving wire is used to cut complex outlines and fine details in the required workpiece. the wire is wound on a spool and is kept in constant tension | |
| 294. |
Wire electric discharge (ED) machining is based on the same principle as that of |
| A. | hydro-dynamic edm |
| B. | die-sink edm |
| C. | polar edm |
| D. | non-conventional edm |
| Answer» B. die-sink edm | |
| Explanation: wire electric discharge (ed) machining is based on the same principle as die- | |
| 295. |
The only difference between die-sink EDM and wire cut EDM is the |
| A. | way of material removal |
| B. | electrode used for the machining |
| C. | type of materials machined |
| D. | processing time |
| Answer» B. electrode used for the machining | |
| Explanation: in the die-sink edm method the electrode has the same shapes as the wished machining results. in the wire cut edm method the electrode is a moving wire made from some electrically conducting material. the workpiece is cut with the electrode wire. | |
| 296. |
During wire cut EDM, the size of the cavity produced by the wire while machining depends upon |
| A. | material of the workpiece |
| B. | di-electric fluid used |
| C. | wire material |
| D. | electric current |
| Answer» D. electric current | |
| Explanation: while machining a high electric current passes through the dielectric fluid and heats the workpiece surface from a very small area. the corresponding workpiece area melts and what is left, is a small round cavity. the cavity size depends on the electric current and potential. | |
| 297. |
Sparking gap is the distance between |
| A. | the workpiece and the cnc table |
| B. | the workpiece and the electrode wire |
| C. | the electrode wire and the di-electric fluid |
| D. | the workpiece and the spark plug |
| Answer» B. the workpiece and the electrode wire | |
| Explanation: the distance between the electrode wire and the workpiece is called a sparking gap. the electrode produces shapes that are a sparking gap dimension larger than the programmed shape through which the electrode wire passes. | |
| 298. |
The absolute minimum inner corner radius is |
| A. | the wire radius minus the sparking gap width |
| B. | the sparking gap width minus the wire radius |
| C. | the wire radius plus the sparking gap width |
| D. | double of the wire radius |
| Answer» C. the wire radius plus the sparking gap width | |
| Explanation: the absolute minimum inner corner radius is the wire radius added with the sparking gap width. therefore during machining, the shapes produced have larger dimensions as compared to the shapes mentioned in the program. | |
| 299. |
Which of the following component of the wire cut EDM machine does not get heated? |
| A. | workpiece |
| B. | electrode wire |
| C. | di-electric fluid |
| D. | coils |
| Answer» B. electrode wire | |
| Explanation: the electrode wire moves between two coils with a moderate speed. the part of the wire that actually machines the workpiece is constantly changing. there is no time for the wire to heat up. | |
| 300. |
Which of the following material properties sets restrictions to use wire cut EDM? |
| A. | material type |
| B. | melting point |
| C. | material hardness |
| D. | electrical conductivity |
| Answer» D. electrical conductivity | |
| Explanation: as the electrode wire does not get heated during machining, the problems with electrode wear are not an issue like in the case of die-sink ed machining and it is possible to use wire cut edm also for materials with high melting ranges. the material hardness sets no restrictions. the only restriction is that the material needs to be electrically conductive. | |
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