EDM

 

ELECTRO DISCHARGE MACHINING

 
1. 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
Explanation: Electro discharge machining is used to machine complex shapes to a high degree of accuracy.
 
2. 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
Explanation: EDM is used to machine materials such as carbides, heat resistant and super alloys which are difficult-to-machine materials.
 
3. Which of the following are the applications of Electro discharge machining?
a) Holes
b) Slots
c) Texturing
d) All of the mentioned
Answer: d
Explanation: Micromachining of holes, slots, dies, texturing, milling, surface modification and mechanical pulsing are some typical applications of Electro discharge machining.
 
4. State whether the following statement is true or false regarding the applications of EDM.
“In advanced machining processes, the incorporation of EDM with CIM increased the length of time for unit operation.”
a) True
b) False
Answer: b
Explanation: The incorporation of EDM in CIM reduced the length of time per unit operation.
 
5. 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
Explanation: Tubular electrode is mostly preferred in Electro discharge machining, for drilling purpose.
 
6. 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
Explanation: EDM drilling uses a tubular electrode which flushes the dielectric thorough the interior holes for removing debris.
 
7. 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
Explanation: Drilling of work piece using EDM produced holes which can be irregular, curved, tapered as well as inclined holes.
 
8. 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
Explanation: Usually a feed rate of 0.10 mm/min is used for drilling the work piece using Electro discharge machining.
 
9. What are range of diameter values obtained by drilling using EDM?
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: b
Explanation: Diameter values while drilled using Electro discharge machining, ranges from 0.10 to 0.50 mm.
 
10. What are the values of overcuts left behind after drilling of work piece?
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
Explanation: Overcut values from 0.01 to 0.05 mm are obtained after the drilling process in EDM.
 
11. 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
Explanation: Electro discharge sawing is an application of EDM which employs either steel band or disc as tool.
 
12. When compared to the conventional abrasive sawing, how many times faster is the MRR?
a) Twice
b) Thrice
c) Four
d) Five
Answer: a
Explanation: Electro discharge sawing cuts the work piece material at the rates which are twice that of conventional abrasive sawing method.
 
13. How much amount of burr is produce while machined using Electro discharge sawing?
a) 10%
b) 20%
c) 50%
d) No Burr
Answer: d
Explanation: The cuts produced in Electro discharge sawing have smaller kerf widths which hav no burrs in it.
 
14. What are the values of finish obtained by machining work piece thorough Electro discharge sawing?
a) 0.1 to 4 µm
b) 6.3 to 10 µm
c) 12.4 to 23 µm
d) 25.6 to 40 µm
Answer: b
Explanation: The finish obtained ranges from 6.3 to 10 µm when machined using Electro discharge sawing.
 
15. What are the recast layer thickness values obtained in ED 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
Explanation: The recast layer thickness values obtained from ED sawing range from 0.025 to 0.13 mm.
 
16. 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
Explanation: Feed control system is used to maintain constant gap between electrodes.
 
17. 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
Explanation: Power supply system is used to supply pulses at certain voltages, current, on time and off time.
 
18. 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
Explanation: Dielectric circulation unit is used to supply dielectric fluid for flushing.
 
19. Which of the following materials are used as electrodes in EDM?
a) Graphite     
b) Copper       
c) Brass          
d) All of the mentioned
Answer: d
Explanation: All the materials mentioned above, can be used as electrodes in Electro discharge machining.
 
20. 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
Explanation: In EDM, metals with high melting point and good electrical conductivity are used as tools.
 
21. Copper has _____ Electro discharge machining wear and _____ conductivity.
a)                  Good, better               
b)                  Good, worse  
c)                  Bad, better                 
d)                 Bad, worse
Answer: a
Explanation: Cu is the metal which has better conductivity and good electro discharge machining wear.
 
22. 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
Explanation: Both Silver tungsten and copper tungsten are the tungsten carbides used in EDM.
 
23. 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
Explanation: Sheet metal is placed over the material in machining of insulating materials using EDM.
 
24. 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
Explanation: Sparks occur between sheet metal and tool electrode for machining insulating ceramics.
 
 Ref: https://www.sanfoundry.com/advanced-machining-questions-answers-edm-applications-1/
R.Satheesh