McqMate
| 201. |
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 |
| Answer» D. high | |
| Explanation: in electro discharge machining, materials having low melting point have high material removal rates and vice-versa. | |
| 202. |
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 |
| Answer» A. rough | |
| Explanation: in electro discharge machining, materials having low melting point have high rougher surfaces and vice-versa. | |
| 203. |
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 |
| Answer» A. decreases | |
| Explanation: in edm, if sparks generated are less then material removal rate decreases. | |
| 204. |
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 |
| Answer» B. inversely proportional | |
| Explanation: in electro discharge machining, material removal rate is inversely proportional to the melting point. | |
| 205. |
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 |
| Answer» A. increase | |
| Explanation: by keeping pulse time constant and increasing current, crater size also increases. | |
| 206. |
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 |
| Answer» B. decrease | |
| Explanation: by decreasing pulse time and keeping current constant, crater size also decreases | |
| 207. |
On which of the following factors do the craters depend? |
| A. | physical properties |
| B. | mechanical properties |
| C. | composition of medium |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: in edm, craters depend on the physical and mechanical properties of material and composition of medium. | |
| 208. |
The maximum depth of damaged layer is how many times that of average surface roughness? |
| A. | 1.5 time |
| B. | 2 times |
| C. | 2.5 times |
| D. | 3 times |
| Answer» C. 2.5 times | |
| Explanation: depth of damaged layer is two and half times the average surface roughness value. | |
| 209. |
What happens to the surface roughness values if the MRR increases in EDM? |
| A. | increases |
| B. | decreases |
| C. | decrease and increase |
| D. | none of the mentioned |
| Answer» A. increases | |
| Explanation: in edm, the surface roughness values increases linearly with increase in the material removal rates. | |
| 210. |
In Electro discharge machining, what happens to the surface finish if the pulse energy is decreased? |
| A. | reduces |
| B. | decreases |
| C. | improves |
| D. | none of the mentioned |
| Answer» C. improves | |
| Explanation: in electro discharge machining, the surface finish improves if the pulse energy is decreased. | |
| 211. |
Using of a mate electrode in Electro discharge machining the surface roughness of material. |
| A. | increases |
| B. | decreases |
| C. | enhances |
| D. | none of the mentioned |
| Answer» B. decreases | |
| Explanation: by using a mate electrode in electro discharge machining, the surface roughness values are decreased. | |
| 212. |
What happens to the surface roughness if oxygen gas is introduced in the gap? |
| A. | increases |
| B. | decreases |
| C. | decrease and then increase |
| D. | all of the mentioned |
| Answer» B. decreases | |
| Explanation: in edm, surface roughness increases with the supply of oxygen gas in gaps. | |
| 213. |
What are the tolerance values obtained by machining using EDM? |
| A. | ± 10 mm |
| B. | ± 15 mm |
| C. | ± 25 mm |
| D. | ± 40 mm |
| Answer» C. ± 25 mm | |
| Explanation: the tolerance values of ± 25 mm are obtained when we machine components using edm. | |
| 214. |
How much extra tolerances are achieved when we choose proper variables? |
| A. | ± 5 mm |
| B. | ± 10 mm |
| C. | ± 15 mm |
| D. | ± 20 mm |
| Answer» A. ± 5 mm | |
| Explanation: extra tolerances of ± 5 mm are obtained with a proper choice of process variables | |
| 215. |
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 |
| Answer» A. 1 µm | |
| Explanation: when a power of 5 µj is given, recast layer thickness of 1 µm is obtained. | |
| 216. |
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 |
| Answer» A. directly proportional | |
| Explanation: the depth of annealed surface in edm is proportional to the amount of power used. | |
| 217. |
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 |
| Answer» A. stable | |
| Explanation: in electro discharge machining, choosing the electrodes which produce more stable machining reduces the annealing effect. | |
| 218. |
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 |
| Answer» B. reduces | |
| Explanation: the altered surface layers that are produced in electro discharge machining, significantly reduces the fatigue strength of alloys. | |
| 219. |
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 |
| Answer» D. all of the mentioned | |
| Explanation: altered layers consists of recast layers, tempered layers, hazs and intergranular precipitates in edm. | |
| 220. |
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 |
| Answer» B. <0.125 mm | |
| Explanation: the thickness of layer obtained after machining is <0.127 mm in edm. | |
| 221. |
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 |
| Answer» A. <0.075 mm | |
| Explanation: the thickness of layer obtained during edm finishing is <0.075 mm. | |
| 222. |
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 |
| Answer» D. all of the mentioned | |
| Explanation: for removal of altered layers processes such as low-stress grinding, chemical machining, reheat treatment, metallurgical type coating and application of shot peening. | |
| 223. |
State whether the 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 |
| Answer» B. false | |
| Explanation: after machining using edm, post treatment to restore the fatigue strength is recommended. | |
| 224. |
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 |
| Answer» C. all of the mentioned | |
| Explanation: electro discharge machining is used to machine complex shapes to a high degree of accuracy. | |
| 225. |
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 |
| Answer» D. all of the mentioned | |
| Explanation: edm is used to machine materials such as carbides, heat resistant and super alloys which are difficult-to-machine materials. | |
| 226. |
Which of the following are the applications of Electro discharge machining? |
| A. | holes |
| B. | slots |
| C. | texturing |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: micromachining of holes, slots, dies, texturing, milling, surface modification and mechanical pulsing are some typical applications of electro discharge machining. | |
| 227. |
Which type of electrode is used for drilling in Electro discharge machining? |
| A. | flat electrode |
| B. | cuboidal electrode |
| C. | tubular electrode |
| D. | spherical electrode |
| Answer» C. tubular electrode | |
| Explanation: tubular electrode is mostly preferred in electro discharge machining, for drilling purpose. | |
| 228. |
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 |
| Answer» A. interior hole | |
| Explanation: edm drilling uses a tubular electrode which flushes the dielectric thorough the interior holes for removing debris. | |
| 229. |
Which type of holes can be produced through drilling using Electro discharge machining? |
| A. | irregular |
| B. | curved |
| C. | tapered |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: drilling of work piece using edm produced holes which can be irregular, curved, tapered as well as inclined holes. | |
| 230. |
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 |
| Answer» A. 0.1 mm/min | |
| Explanation: usually a feed rate of 0.10 mm/min is used for drilling the work piece using electro discharge machining. | |
| 231. |
10 to 0.50 mm. |
| A. | 0.01 to 0.05 mm |
| B. | 0.1 to 0.5 mm |
| C. | 1 to 5 mm |
| D. | 10 to 15 mm |
| Answer» A. 0.01 to 0.05 mm | |
| Explanation: overcut values from 0.01 to 0.05 mm are obtained after the drilling process in edm. | |
| 232. |
Electro discharge sawing is an application of EDM which employs as tool material. |
| A. | steel band |
| B. | disc |
| C. | steel band & disc |
| D. | none of the mentioned |
| Answer» C. steel band & disc | |
| Explanation: electro discharge sawing is an application of edm which employs either steel band or disc as tool. | |
| 233. |
When compared to the conventional abrasive sawing, how many times faster is the MRR? |
| A. | twice |
| B. | thrice |
| C. | four |
| D. | five |
| Answer» A. twice | |
| Explanation: electro discharge sawing cuts the work piece material at the rates which are twice that of conventional abrasive sawing method. | |
| 234. |
How much amount of burr is produce while machined using Electro discharge sawing? |
| A. | 10% |
| B. | 20% |
| C. | 50% |
| D. | no burr |
| Answer» D. no burr | |
| Explanation: the cuts produced in electro discharge sawing have smaller kerf widths which hav no burrs in it. | |
| 235. |
3 to 10 µm when machined using Electro discharge 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 |
| Answer» B. 0.025 to 0.130 mm | |
| Explanation: the recast layer thickness values obtained from ed sawing range from 0.025 to | |
| 236. |
Which of the following electrodes are used for machining spherical surfaces in Electro discharge machining? |
| A. | tubular electrodes |
| B. | flat electrodes |
| C. | cuboidal electrodes |
| D. | all of the mentioned |
| Answer» A. tubular electrodes | |
| Explanation: simple tubular electrodes are used to machine convex and concave spherical surfaces. | |
| 237. |
What are the values of dimensional accuracy obtained while machining spherical surfaces? |
| A. | ± 1 µm |
| B. | ± 3 µm |
| C. | ± 5 µm |
| D. | ± 7 µm |
| Answer» A. ± 1 µm | |
| Explanation: dimensional accuracy of ± 1 µm is obtained while machining spherical surfaces using edm. | |
| 238. |
What are the surface roughness values obtained while machining spherical surfaces using Electro discharge machining? |
| A. | <0.1 µm |
| B. | <0.3 µm |
| C. | <0.5 µm |
| D. | <0.7 µm |
| Answer» A. <0.1 µm | |
| Explanation: the surface roughness values obtained while machining of spherical surfaces are <0.1 µm in electro discharge machining. | |
| 239. |
Which motion of tool is used for machining spherical surfaces in Electro discharge machining? |
| A. | oscillatory |
| B. | vibratory |
| C. | rotary |
| D. | all of the mentioned |
| Answer» C. rotary | |
| Explanation: the rotary motion tool is used for machining spherical surfaces of conducting ceramic materials in edm. | |
| 240. |
Which type of electrodes are used for milling application in Electro discharge machining process? |
| A. | tubular type electrodes |
| B. | cylindrical type electrodes |
| C. | flat type electrodes |
| D. | spherical type electrodes |
| Answer» B. cylindrical type electrodes | |
| Explanation: standard cylindrical electrodes are used for milling application in edm process. | |
| 241. |
Which type of cavities can be machined using milling process by Electro discharge machining? |
| A. | complex cavities |
| B. | simple cavities |
| C. | simple & complex cavities |
| D. | none of the mentioned |
| Answer» C. simple & complex cavities | |
| Explanation: simple cavities and complex cavities are machined by successive nc sweeps of electrode over the desired path. | |
| 242. |
The simple electrodes are rotated at which speed for milling of work pieces in Electro discharge machining? |
| A. | very low |
| B. | low |
| C. | medium |
| D. | high |
| Answer» D. high | |
| Explanation: simple electrodes are rotated at high speeds for milling in electro discharge machining same as that of conventional milling. | |
| 243. |
What happens to the dielectric flushing while milling tool is rotated at a high speed in EDM? |
| A. | improved |
| B. | worsen |
| C. | reduced |
| D. | all of the mentioned |
| Answer» A. improved | |
| Explanation: milling by electro discharge machining enhances the dielectric flushing due to high speed rotation of tool. | |
| 244. |
Which of the following are the steps included in the die sinking process of EDM? |
| A. | cad of electrode |
| B. | electrode manufacturing |
| C. | programming for die sinking |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: designing of electrode, then manufacturing, and programming of die sinking are the steps to be followed for die sinking process in edm. | |
| 245. |
Which path of the components in wire EDM determines the path to be machined? |
| A. | horizontal worktable movement |
| B. | vertical worktable movement |
| C. | horizontal & vertical worktable movement |
| D. | none of the mentioned |
| Answer» A. horizontal worktable movement | |
| Explanation: horizontal movement of the work table determines the path to be machined in wire electro discharge machining. | |
| 246. |
Which of the following materials are machined using Wire Electro discharge machining? |
| A. | polycrystalline diamond |
| B. | cubic boronitride |
| C. | matrix composites |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: polycrystalline diamond (pcd), cubic boron nitride (cbn) and other matrix composites are the material than can be machined using wire edm. | |
| 247. |
How much amount of burr is produce when we use Wire Electro discharge machining for machining of work pieces? |
| A. | 10% |
| B. | 20% |
| C. | no burr |
| D. | small amount |
| Answer» C. no burr | |
| Explanation: in wire electro discharge machining no burr is produced without any distortion while machining work pieces. | |
| 248. |
Which of the following industries use wire EDM for different applications? |
| A. | chemical industry |
| B. | aerospace industry |
| C. | automobile industry |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: industries such as chemical, aerospace, automobile, nuclear etc.., use wire edm for a wide variety of applications in their industries | |
| 249. |
While machining insulating ceramic materials using EDM, where is the sheet metal placed? |
| A. | over material |
| B. | below material |
| C. | under material |
| D. | none of the mentioned |
| Answer» A. over material | |
| Explanation: sheet metal is placed over the material in machining of insulating materials using edm. | |
| 250. |
Sparks occur between which of the following components? |
| A. | work piece and sheet metal |
| B. | tool electrode and sheet metal |
| C. | work piece and electrode |
| D. | none of the mentioned |
| Answer» B. tool electrode and sheet metal | |
| Explanation: sparks occur between sheet metal and tool electrode for macining insulating ceramics. | |
| 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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