McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 151. |
Which of the following geometries can be machined using EDM? |
| A. | simple |
| B. | complex |
| C. | difficult to cut |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: electrodischarge machining can be used for simple as well as complex geometries. | |
| 152. |
State whether the following statement is true or false regarding EDM. “In EDM, process is affected by hardness of material.” |
| A. | true |
| B. | false |
| Answer» B. false | |
| Explanation: edm process is not affected by the hardness of material. | |
| 153. |
Which of the following mechanisms is used for material removal? |
| A. | electro discharge erosion |
| B. | magnetic abrasion |
| C. | electro chemical dissolution |
| D. | mechanical erosion |
| Answer» A. electro discharge erosion | |
| Explanation: material is removed by electro-discharge erosion (ede) in edm | |
| 154. |
What is the value of order of frequency applied between the two electrodes in EDM? |
| A. | 1 khz |
| B. | 3 khz |
| C. | 5 khz |
| D. | 7 khz |
| Answer» C. 5 khz | |
| Explanation: the magnitude of frequency applied between the electrodes in edm is about 5 khz. | |
| 155. |
What are the magnitude of voltages used in Electro discharge machining? |
| A. | 1 to 20 v |
| B. | 20 to 120 v |
| C. | 120 to 220 v |
| D. | 220 to 320 v |
| Answer» B. 20 to 120 v | |
| Explanation: in edm, the magnitude of voltages range between 20 and 120 v. | |
| 156. |
How is material removed in Electro discharge machining? |
| A. | melt and evaporate |
| B. | corrode and break |
| C. | mechanical erosion takes place |
| D. | none of the mentioned |
| Answer» A. melt and evaporate | |
| Explanation: in electro discharge machining, material is melted and then evaporated. | |
| 157. |
What is the radius of channel, when electrical breakdown occur? |
| A. | 4 µm |
| B. | 6 µm |
| C. | 8 µm |
| D. | 10 µm |
| Answer» D. 10 µm | |
| Explanation: in edm, the electrical breakdown occurs in dielectric in a channel of radius about 10 µm. | |
| 158. |
State whether the following statement is true or false about material removal in EDM. “In EDM, high pressures allow the metal to evaporate.” |
| A. | true |
| B. | false |
| Answer» B. false | |
| Explanation: high pressures in edm try to prevent the super-heated metal from evaporation. | |
| 159. |
What are the values of pressure of the plasma in EDM? |
| A. | up to 2 atm |
| B. | up to 20 atm |
| C. | up to 200 atm |
| D. | up to 2000 atm |
| Answer» C. up to 200 atm | |
| Explanation: pressure on the plasma channel rises to values as high as 200 atm when dielectric evaporates. | |
| 160. |
At the end of pulse, super-heated metal evaporates |
| A. | explosively |
| B. | normally |
| C. | periodically |
| D. | occasionally |
| Answer» A. explosively | |
| Explanation: at the end of pulse, pressure drops suddenly and super-heated metal evaporates explosively. | |
| 161. |
After the explosion is over, how is the debris carried away? |
| A. | evaporation |
| B. | fresh dielectric |
| C. | old dielectric |
| D. | all of the mentioned |
| Answer» B. fresh dielectric | |
| Explanation: debris is carried away by the fresh dielectric that rushes in. | |
| 162. |
The layer formed when un expelled molten metal solidifies is known as |
| A. | reabsorbed layer |
| B. | recast layer |
| C. | un evaporated layer |
| D. | condensed layer |
| Answer» B. recast layer | |
| Explanation: unexpelled molten metal solidifies to form a layer known as recast layer. | |
| 163. |
Amount of material removed from anode and cathode depend on which of the following? |
| A. | electrons |
| B. | positive ions |
| C. | electrons & positive ions |
| D. | none of the mentioned |
| Answer» C. electrons & positive ions | |
| Explanation: the amount of material removed from electrodes depend on the contribution of the charged ions. | |
| 164. |
What happens when the electron current predominates in the discharge? |
| A. | more anodic removal |
| B. | more cathodic removal |
| C. | remains same |
| D. | all of the mentioned |
| Answer» A. more anodic removal | |
| Explanation: when electron current predominates the electrical discharge, anodic material removal is greater than cathodic material. | |
| 165. |
What is the value of gap maintained between the electrodes when we use servo mechanism? |
| A. | 10 – 100 µm |
| B. | 100 – 200 µm |
| C. | 200 – 500 µm |
| D. | 500 – 1000 µm |
| Answer» C. 200 – 500 µm | |
| Explanation: in edm, value of gap maintained between the electrodes range between 200 and 500 µm. | |
| 166. |
Based on the electrode gap, which of the following electric pulses are generated? |
| A. | open circuit pulses |
| B. | sparks |
| C. | arcs |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: based on the electrode gap, electric pulses are distinguished which are – circuit pulses, sparks, arcs and short circuits. | |
| 167. |
When the electrode gap is too small or electrodes are in contact, how much material is removed? |
| A. | 10% |
| B. | 20% |
| C. | 30% |
| D. | no material removed |
| Answer» D. no material removed | |
| Explanation: when electrodes come in contact with one another, short circuits occur and material removed is not possible. | |
| 168. |
Which components mentioned below are affected due to arcs? |
| A. | work piece |
| B. | tool |
| C. | work piece & tool |
| D. | none of the mentioned |
| Answer» C. work piece & tool | |
| Explanation: arcs are believed to occur at same spots on electrode surfaces which damage both tool and work piece. | |
| 169. |
Which of the following pulses contribute to the desired material removal in EDM? |
| A. | open circuit pulses |
| B. | short circuits |
| C. | arcs |
| D. | sparks |
| Answer» D. sparks | |
| Explanation: the sparks are the one which contributes to the desired material removal in electro discharge machining. | |
| 170. |
Which of the following are main components of EDM? |
| A. | dielectric system |
| B. | servomechanism |
| C. | power supply |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: main components of machining system in edm are – dielectric system, power supply and servomechanism. | |
| 171. |
What is the function of feed-control system in Electro discharge machining? |
| A. | constant gap |
| B. | supply power |
| C. | dielectric fluid supply |
| D. | work piece holding |
| Answer» A. constant gap | |
| Explanation: feed control system is used to maintain constant gap between electrodes. | |
| 172. |
What is the use of power supply system in Electro discharge machining? |
| A. | constant gap |
| B. | supply power |
| C. | dielectric fluid supply |
| D. | work piece holding |
| Answer» B. supply power | |
| Explanation: power supply system is used to supply pulses at certain voltages, current, on time and off time. | |
| 173. |
What is the function of dielectric circulation unit in Electro discharge machining? |
| A. | constant gap |
| B. | supply power |
| C. | dielectric fluid supply |
| D. | work piece holding |
| Answer» C. dielectric fluid supply | |
| Explanation: dielectric circulation unit is used to supply dielectric fluid for flushing. | |
| 174. |
Which of the following materials are used as electrodes in EDM? |
| A. | graphite |
| B. | copper |
| C. | brass |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: all the materials mentioned above, can be used as electrodes in electro discharge machining. | |
| 175. |
Metals with melting point and electrical conductivity are chosen as tools in EDM. |
| A. | low, good |
| B. | low, bad |
| C. | high, good |
| D. | high, bad |
| Answer» C. high, good | |
| Explanation: in edm, metals with high melting point and good electrical conductivity are used as tools. | |
| 176. |
Copper has Electro discharge machining wear and conductivity. |
| A. | good, better |
| B. | good, worse |
| C. | bad, better |
| D. | bad, worse |
| Answer» A. good, better | |
| Explanation: cu is the metal which has better conductivity and good electro discharge machining wear. | |
| 177. |
Which of the following tungsten carbides are used as electrodes in EDM? |
| A. | silver tungsten |
| B. | copper tungsten |
| C. | all of the mentioned |
| D. | none of the mentioned |
| Answer» C. all of the mentioned | |
| Explanation: both silver tungsten and copper tungsten are the tungsten carbides used in edm. | |
| 178. |
Brass metal ensures which type of sparking conditions in Electro discharge machining? |
| A. | stable |
| B. | unstable |
| C. | unsteady |
| D. | insecure |
| Answer» A. stable | |
| Explanation: brass is a type of metal which ensures stable sparking conditions in electro discharge machining. | |
| 179. |
In addition to the feed of tool, Electro discharge machining tool can have which type of motion? |
| A. | oscillatory |
| B. | rotary |
| C. | vibrational |
| D. | all of the mentioned |
| Answer» B. rotary | |
| Explanation: in addition to feed, the tool electrode may have rotary or orbiting motion. | |
| 180. |
Which of the following parameters determines the size of cavities? |
| A. | size of electrode |
| B. | radius of orbit |
| C. | all of the mentioned |
| D. | none of the mentioned |
| Answer» C. all of the mentioned | |
| Explanation: size of electrode and radius of orbit determines the size of cavities in edm. | |
| 181. |
Electrode orbiting the flushing of dielectric fluid in Electro discharge machining. |
| A. | improves |
| B. | decreases |
| C. | reduces |
| D. | degrades |
| Answer» A. improves | |
| Explanation: the additional orbiting motion of electrodes helps in improving the flushing by creating a pumping effect of dielectric liquid. | |
| 182. |
Quality of hole produced by orbiting motion is to that obtained by using stationary electrode. |
| A. | inferior |
| B. | superior |
| C. | lower |
| D. | all of the mentioned |
| Answer» B. superior | |
| Explanation: quality of hole produced by orbiting motion is superior to that obtained by using stationary electrode. | |
| 183. |
In EDM, electrode polarity depends up on which of the following components? |
| A. | work piece |
| B. | electrode material |
| C. | all of the mentioned |
| D. | none of the mentioned |
| Answer» C. all of the mentioned | |
| Explanation: in electro discharge machining, electrode polarity depends on both work piece and electrode material | |
| 184. |
Which one among the following, is the most important factor in determining the tool wear? |
| A. | melting point |
| B. | boiling point |
| C. | power supplied |
| D. | feed rate |
| Answer» A. melting point | |
| Explanation: in edm, melting point is the most important factor in determining the tool wear. | |
| 185. |
Electrode wear ratios can be expressed as, which of the following wears? |
| A. | end wear |
| B. | side wear |
| C. | corner wear |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: electrode wear ratios are expressed as end wear, corner wear, side wear and volume wear. | |
| 186. |
Which of the following are the other factors that influence the electrode wear? |
| A. | voltage |
| B. | current |
| C. | electrode material |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: in edm, electrode wear depends on the factors such as voltage, current, electrode material and polarity. | |
| 187. |
State whether the following statement is true or false regarding wear in EDM. “In EDM, electrode wear is less dominant when it comes to micromachining applications.” |
| A. | true |
| B. | false |
| Answer» B. false | |
| Explanation: electrode wear is more when it comes to micromachining applications in edm. | |
| 188. |
State whether the following statement is true or false regarding wear in EDM. “In EDM, corner wear ratio does not depend on type of electrode material.” |
| A. | true |
| B. | false |
| Answer» B. false | |
| Explanation: in edm, corner wear ratio depend on the material of electrode used. | |
| 189. |
In Electro discharge machining, highest wear ratio is associated with which type of melting point? |
| A. | low |
| B. | medium |
| C. | high |
| D. | very high |
| Answer» A. low | |
| Explanation: in electro discharge machining, lowering of the melting point of electrode material results in high wear ratio. | |
| 190. |
Which of the following is not a function of dielectric in EDM? |
| A. | flush particles |
| B. | cool the section |
| C. | maintain voltage |
| D. | provide insulation |
| Answer» C. maintain voltage | |
| Explanation: flushing particles, providing insulation and cooling the sections that are heated, are the functions of dielectric. | |
| 191. |
Which of the following are the main requirements of dielectric fluids? |
| A. | viscosity |
| B. | high flash point |
| C. | minimum odour |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: adequate viscosity, high flash point, oxidation stability, minimum odour, low cost and good electrical discharge are the main requirements of dielectric fluids. | |
| 192. |
Which of the following can be used as dielectric fluids in EDM? |
| A. | kerosene |
| B. | silicon fluids |
| C. | distilled water |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: the dielectric fluids used are kerosene, silicon fluid, ethylene glycol, water in emulsions and distilled water. | |
| 193. |
In EDM, inadequate flushing will not result in which of the following consequences? |
| A. | arcing |
| B. | debris removal |
| C. | decrease electrode life |
| D. | increased production time |
| Answer» B. debris removal | |
| Explanation: inadequate flushing in electro discharge machining results in less removal or no removal of debris. | |
| 194. |
Which methods below, are used for introducing the dielectric in machining gap? |
| A. | normal flow |
| B. | reverse flow |
| C. | jet flushing |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: four methods namely normal flow, reverse flow, jet flushing and immersion flushing are used for introducing dielectric. | |
| 195. |
Few large holes are than many small flushing holes in Electro discharge machining. |
| A. | worse |
| B. | better |
| C. | well |
| D. | none of the mentioned |
| Answer» A. worse | |
| Explanation: many small holes are better than a few large holes in machining thorough the edm process. | |
| 196. |
State whether the following statement is true or false regarding the dielectric in EDM. “In EDM, flushing through the tool is more preferred than side flushing.” |
| A. | true |
| B. | false |
| Answer» A. true | |
| Explanation: flushing through the tool is preferred than side flushing for deep cuts. | |
| 197. |
In Electro discharge machining, which type of dielectric flow mentioned below is desirable? |
| A. | unsteady flow |
| B. | steady flow |
| C. | unstable flow |
| D. | none of the mentioned |
| Answer» B. steady flow | |
| Explanation: in edm, steady dielectric flow on the entire electrode-work piece interfaces is most desirable | |
| 198. |
Metal is removed on which of the components in electro discharge machining? |
| A. | electrode tool |
| B. | work piece |
| C. | electrode tool & work piece |
| D. | none of the mentioned |
| Answer» C. electrode tool & work piece | |
| Explanation: in electro discharge machining, material is removed from both tool and work piece. | |
| 199. |
On which of the following components, does the MRR depend? |
| A. | work piece |
| B. | electrode tool |
| C. | electrode tool & work piece |
| D. | none of the mentioned |
| Answer» C. electrode tool & work piece | |
| Explanation: material removal rate not only depends on work piece material but also the tool material. | |
| 200. |
Which of the following factors influence the material removal rate? |
| A. | pulse condition |
| B. | electrode polarity |
| C. | machining medium |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: the factors such as pulse conditions, electrode polarity and machining medium also affect the material removal rate. | |
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