McqMate
These multiple-choice questions (MCQs) are designed to enhance your knowledge and understanding in the following areas: Mechanical Engineering .
| 551. |
Too small gap causes which of the following effects? |
| A. | sparking |
| B. | short circuit |
| C. | sparking & short circuit |
| D. | none of the mentioned |
| Answer» C. sparking & short circuit | |
| Explanation: sparking or short circuit occurs when the gap is too small | |
| 552. |
Electro chemical dissolution phase starts with the movement of ions between which two components? |
| A. | cathode and anode |
| B. | cathode and power source |
| C. | power source and anode |
| D. | power source and electrolyte |
| Answer» A. cathode and anode | |
| Explanation: ecd phase occurs by the movement of ions between the two electrodes. | |
| 553. |
Better surface finish and higher accuracy depend on which of the factors below? |
| A. | chemical composition of the electrolyte |
| B. | current density |
| C. | all of the mentioned |
| D. | none of the mentioned |
| Answer» C. all of the mentioned | |
| Explanation: proper chemical composition of electrolyte and proper current density are responsible for better surface finish and accuracy. | |
| 554. |
For alloys, which type of electrolyte is used in ECM? |
| A. | single component |
| B. | double component |
| C. | multi component |
| D. | triple component |
| Answer» C. multi component | |
| Explanation: depending up on the elements in an alloy multi component electrolytes are used. | |
| 555. |
Nickel can be machined with 100% current efficiency, when current density value is |
| A. | 10 a/cm2 |
| B. | 25 a/cm2 |
| C. | 45 a/cm2 |
| D. | 80 a/cm2 |
| Answer» B. 25 a/cm2 | |
| Explanation: nickel is a metal suggested by khayry, which can be machined at 100% current efficiency, if current density is 25 a/cm2. | |
| 556. |
When the electrolyte flow is low, what happens to the current efficiency? |
| A. | increases |
| B. | decreases |
| C. | remains same |
| D. | increase and then decrease |
| Answer» B. decreases | |
| Explanation: in ecm, if the electrolyte flow is low, current efficiency is reduced due to the accumulation of machining products within the gap. | |
| 557. |
When machining Ti, in Nacl electrolyte, what values of current efficiencies are obtained? |
| A. | 10 – 20 % |
| B. | 20 – 30 % |
| C. | 30 – 50 % |
| D. | 50 – 80 % |
| Answer» A. 10 – 20 % | |
| Explanation: while machining ti using nacl electrolyte, current efficiencies of 10 – 20 percent are obtained. | |
| 558. |
State whether the following statement is true or false about electrolyte in ECM. “Machinability in ECM is enhanced, when electrolyte is heated.” |
| A. | true |
| B. | false |
| Answer» A. true | |
| Explanation: machinability is increased, when electrolyte is heated, as heating increases the specific conductivity of the electrolyte. | |
| 559. |
What must be the working voltage in Electrochemical machining? |
| A. | 10 v |
| B. | 20 v |
| C. | 30 v |
| D. | 40 v |
| Answer» B. 20 v | |
| Explanation: the electrolytes in ecm employ a working voltage up to 20 v. | |
| 560. |
Surface roughness depend on which of the following quantities? |
| A. | crystallographic irregularities |
| B. | alloy composition |
| C. | distribution of current density |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: surface roughness of machined surface in ecm depend on crystallographic irregularities, alloy composition, current density distribution, dislocations and grain boundaries. | |
| 561. |
For a better surface finish, which type of current distribution is required? |
| A. | even |
| B. | uneven |
| C. | even & uneven |
| D. | none of the mentioned |
| Answer» A. even | |
| Explanation: more even distribution of the current density leads to a better surface finish. | |
| 562. |
Between which values does the side gap’s surface roughness vary? |
| A. | >1 µm |
| B. | >3 µm |
| C. | >5 µm |
| D. | >7 µm |
| Answer» C. >5 µm | |
| Explanation: surface roughness value is 5 µm or more for side gap areas. | |
| 563. |
In Electrochemical machining, larger grain size causes which type of finish? |
| A. | smoother |
| B. | rougher |
| C. | finer |
| D. | all of the mentioned |
| Answer» B. rougher | |
| Explanation: in ecm, larger grains cause rougher finish than finer grains | |
| 564. |
Which type of gap width is necessary for a higher degree of accuracy? |
| A. | very small |
| B. | small |
| C. | medium |
| D. | high |
| Answer» B. small | |
| Explanation: a small gap width represents a high level of accuracy. very small gap width results in sparks and short circuits. | |
| 565. |
Accuracy of machining is affected by, which of the following factors? |
| A. | material |
| B. | gap voltage |
| C. | feed rate |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: accuracy of the process is affected by material equivalent, gap voltage, feed rate, etc. | |
| 566. |
Which properties of electrolyte does not affect the accuracy of the process? |
| A. | temperature |
| B. | concentration |
| C. | non-reactive |
| D. | pressure |
| Answer» C. non-reactive | |
| Explanation: electrolyte must be reactive in order to carry on the reactions that occur at the electrodes. | |
| 567. |
For high process accuracy, which of the following factors are needed? |
| A. | high feed rate |
| B. | high conductivity |
| C. | high feed rate & high conductivity |
| D. | none of the mentioned |
| Answer» C. high feed rate & high conductivity | |
| Explanation: for a higher degree of accuracy, there must be high feed rates and highly conductive electrolytes. | |
| 568. |
Tool insulation that the side machining action is needed in the process of ECM. |
| A. | limits |
| B. | enhances |
| C. | maintains |
| D. | none of the mentioned |
| Answer» A. limits | |
| Explanation: tool insulation is needed, which limits the machining of other sides of work piece. | |
| 569. |
If the current density is high as required, what type of machining occurs? |
| A. | pitting |
| B. | polishing |
| C. | etching |
| D. | all of the mentioned |
| Answer» B. polishing | |
| Explanation: when the current density is relatively high as required, then polishing occurs. | |
| 570. |
What happens when the current density is low in ECM? |
| A. | pitting occurs |
| B. | etching occurs |
| C. | pitting & etching occurs |
| D. | none of the mentioned |
| Answer» C. pitting & etching occurs | |
| Explanation: when current density is lower than optimum, then etching and pitting occurs which are undesired. | |
| 571. |
Fine dimensional control can be obtained if throwing power of electrolyte is |
| A. | low |
| B. | medium |
| C. | high |
| D. | very high |
| Answer» A. low | |
| Explanation: throwing power of electrolyte must be less in order to obtain a fine dimensional control. | |
| 572. |
Passivation is done on electrolytes in order to form which of the following? |
| A. | passive layer on machined parts |
| B. | passive layer on cathode |
| C. | passive layer on machined parts & cathode |
| D. | none of the mentioned |
| Answer» A. passive layer on machined parts | |
| Explanation: passivation is done on the electrolytes in order to form a passive film on machined parts. | |
| 573. |
If there is an increase in the electrolyte flow, what happens to the rate of film formation? |
| A. | increases |
| B. | decreases |
| C. | remains same |
| D. | all of the mentioned |
| Answer» B. decreases | |
| Explanation: an increase in electrolytic solution flow decreases the anodic product formation, which reduces the rate of film formation. | |
| 574. |
It is difficult to machine inner radii smaller than and outer radii less than |
| A. | 0.1 mm, 0.2 mm |
| B. | 0.5 mm, 0.8 mm |
| C. | 0.8 mm, 0.5 mm |
| D. | 0.2 mm, 0.1 mm |
| Answer» C. 0.8 mm, 0.5 mm | |
| Explanation: it is difficult to machine inner radii < 0.8mm and outer radii < 0.5mm. | |
| 575. |
What is the value of the overcut that is obtained using ECM? |
| A. | 0.3 mm |
| B. | 0.5 mm |
| C. | 0.7 mm |
| D. | 0.9 mm |
| Answer» B. 0.5 mm | |
| Explanation: an overcut of 0.5 mm is obtained when machined using ecm | |
| 576. |
If there is a change in the selected machining conditions, it will have impact on which of the following? |
| A. | process accuracy |
| B. | surface finish |
| C. | process accuracy & surface finish |
| D. | none of the mentioned |
| Answer» C. process accuracy & surface finish | |
| Explanation: selected machining conditions should remain unchanged, because, it will have a direct impact on accuracy and surface finish. | |
| 577. |
Surface roughness depends on current density, which is affected by which of the following? |
| A. | tool feed rate |
| B. | gap voltage |
| C. | work piece material |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: roughness depend on current density, which is affected by tool feed rate, gap voltage, work material, ph number, temperature, conductivity and pressure. | |
| 578. |
Machining conditions leading to high accuracy are associated with surface roughness and productivity. |
| A. | greater, greater |
| B. | smaller, greater |
| C. | greater, smaller |
| D. | smaller, smaller |
| Answer» B. smaller, greater | |
| Explanation: accuracy is associated with smaller surface roughness and greater machining productivity. | |
| 579. |
Non stationary behaviour of ECM is due to, which of the factors below? |
| A. | gas generation |
| B. | heating |
| C. | passivation |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: non stationary behaviour of ecm is due to the inter electrode gap conditions such as gas generation, passivation, heating and other electrode reactions. | |
| 580. |
For large components, actual machining time constitutes to how much percentage of the total machining time? |
| A. | very low |
| B. | low |
| C. | medium |
| D. | high |
| Answer» D. high | |
| Explanation: actual machining time of large components constitutes to a high percentage of total machining time. | |
| 581. |
What happens to the product cycle time, if the machining performance is improved? |
| A. | increases |
| B. | decreases |
| C. | remains same |
| D. | none of the mentioned |
| Answer» B. decreases | |
| Explanation: as the machining performance is improved, the time take for a product to complete its production cycle, decreases. | |
| 582. |
The cost of additional control hardware remain a fraction of total machining cost. |
| A. | small |
| B. | large |
| C. | equal |
| D. | none of the mentioned |
| Answer» A. small | |
| Explanation: cost of additional control hardware is very less, which constitutes to a small fraction in total machining cost. | |
| 583. |
With an increase in unmanned machining hours, what happens to the efficiency of ECM? |
| A. | increases |
| B. | reduces |
| C. | decreases |
| D. | increase and then decrease |
| Answer» A. increases | |
| Explanation: increase in unmanned machining hours lead to a raise in efficiency of ecm. | |
| 584. |
Which type of damage is caused by deterioration which is caused by spark? |
| A. | reparable |
| B. | irreparable |
| C. | all of the mentioned |
| D. | none of the mentioned |
| Answer» B. irreparable | |
| Explanation: deterioration by sparking may cause irreparable damage to the work pieces | |
| 585. |
Which of the following use ECM for different applications? |
| A. | gas turbines |
| B. | jet engines |
| C. | bio medical implants |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: ecm has its applications in industries such as gas turbines, jet engines, automobiles, medical etc. | |
| 586. |
Which of the following processes can be done using ECM? |
| A. | die sinking |
| B. | profiling and contouring |
| C. | drilling and trepanning |
| D. | all of the mentioned |
| Answer» D. all of the mentioned | |
| Explanation: ecm can be used for die sinking, trepanning, drilling, contouring, grinding and profiling. | |
| 587. |
Which of the following material cannot be machined using ECM? |
| A. | high strength alloys |
| B. | hardened steels |
| C. | nonconductive materials |
| D. | all of the mentioned |
| Answer» C. nonconductive materials | |
| Explanation: ecm can be used for machining high strength alloys and hardened steels which led to many cost-saving applications. | |
| 588. |
ECM is used to the sharp edges produced after rough cuts. |
| A. | enhance |
| B. | dull |
| C. | improve |
| D. | none of the mentioned |
| Answer» B. dull | |
| Explanation: using deburring process through ecm, sharp edges are dulled, which are produced after rough cuts. | |
| 589. |
ECM is usually characterized as low accuracy machining, for which of the following reason? |
| A. | narrow gap width |
| B. | wider gap width |
| C. | high current densities |
| D. | all of the mentioned |
| Answer» B. wider gap width | |
| Explanation: ecm is usually characterized as low accuracy machining because of its wider machining gap. | |
| 590. |
In micro ECM, which of the following is used as micro tool? |
| A. | electrolyte jet |
| B. | electrodes |
| C. | power supply |
| D. | all of the mentioned |
| Answer» A. electrolyte jet | |
| Explanation: electrolyte jet in micro ecm acts as the micro tool for machining. | |
| 591. |
Micro ECM is used to machine which type of parts? |
| A. | large parts |
| B. | micro parts |
| C. | normal sized parts |
| D. | all of the mentioned |
| Answer» B. micro parts | |
| Explanation: micro ecm is used to machine micro parts which can be from micro scale to mesoscale in size. | |
| 592. |
Which of the following produces small indents and cavities using micro ECM? |
| A. | moving the work piece |
| B. | switching the pulse current |
| C. | moving the work piece & switching the pulse current |
| D. | none of the mentioned |
| Answer» C. moving the work piece & switching the pulse current | |
| Explanation: indentation and cavitation can be done using micro ecm by moving the work piece or switching the pulse current | |
| 593. |
What fraction of tool will always be in contact with the work piece? |
| A. | half |
| B. | full |
| C. | no contact |
| D. | quarter |
| Answer» C. no contact | |
| Explanation: tool does not have any contact with the work piece in electro chemical machining. | |
| 594. |
How much amount of wear is present in the tool used in Electrochemical machining? |
| A. | no wear |
| B. | low |
| C. | medium |
| D. | high |
| Answer» A. no wear | |
| Explanation: the tool wear is absent in the tool used in ecm, since tool has no contact with the work piece. | |
| 595. |
Compared to other processes, machining is done at voltages for high rates of material removal. |
| A. | low |
| B. | medium |
| C. | high |
| D. | very low |
| Answer» C. high | |
| Explanation: in ecm, machining is done at low voltages, when compared to other processes. | |
| 596. |
Very small dimensions, up to which value can be controlled using ECM? |
| A. | 0.01 mm |
| B. | 0.05 mm |
| C. | 0.07 mm |
| D. | 0.12 mm |
| Answer» B. 0.05 mm | |
| Explanation: due to less electrode gap very small dimensions up to 0.05 mm can be controlled. | |
| 597. |
Complicated profiles can be machined in how many operations in Electrochemical machining? |
| A. | single |
| B. | double |
| C. | triple |
| D. | multiple |
| Answer» A. single | |
| Explanation: one of the main advantage of ecm is, complicated profiles can be machined in a single operation itself. | |
| 598. |
How much amount of thermal damage occurs to the work piece? |
| A. | small |
| B. | large |
| C. | no thermal damage |
| D. | negligible amount |
| Answer» C. no thermal damage | |
| Explanation: as the temperatures are very low, no thermal damage occurs to the work piece material. | |
| 599. |
Which of the following materials can be machined using ECM? |
| A. | hard nonconductive materials |
| B. | hard conductive materials |
| C. | all nonconductive materials |
| D. | none of the mentioned |
| Answer» B. hard conductive materials | |
| Explanation: hard conductive materials can be machined and nonconductive materials cannot be machined using ecm. | |
| 600. |
What are the requirements of labour for machining purpose in Electrochemical machining? |
| A. | low |
| B. | medium |
| C. | high |
| D. | very high |
| Answer» A. low | |
| Explanation: in electrochemical machining, labour requirements are low compared to conventional or traditional machining practices. | |
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