Electrical Discharge Machining (EDM): It is also known as Spark Machining or Spark Eroding process.
In this process, electrical energy is used to generate the Spark between the tool and workpiece submerged under the dielectric medium so that material removal takes place from the surface of the workpiece by local melting or Vaporization.
Electrolyte used: Dielectric Fluid (Kerosene).
The dielectric fluid in the normal form acts as insulator whereas at proper voltage or increase in voltage makes the dielectric fluid to be Ionized.
The Optimum gap between the tool and the workpiece is 0.03 mm.
Voltage – 70V
Properties of the Dielectric:
- Low viscosity.
- Remain electrically non-conductive up to the desired voltage breakdown takes place.
- It can act as a good cooling medium.
- It can carry away all the metal particles produced during the spark erosion.
The tool used in the Electric Discharge Machining process is either Copper or Tungsten or Copper-Tungsten Alloy.
Properties Possessed by the Tool:
It must possess high
- Melting Point
- Electrical Conductivity.
MRR(Material Removal Rate):
Out of all the non-traditional machining methods, the Electric Discharge Machining will remove more material. In the sense, the MRR is higher for EDM.
Diagram of Electrical Discharge Machining Process:
The Electrical Discharge Machining(EDM) setup consists of
- Fixture: To hold the table.
- Table: To hold the workpiece.
- Dielectric Medium
- Feed unit (Servo Feed Unit)
- Power supply.
Working of Electrical Discharge Machining(EDM) Process:
The workpiece is fixed in the dielectric container by means of a fixture.
The tool is fed up by the Servo Feed Unit which can move downward in a vertical direction.
The power supply is given to the electrical discharge machining process I.e. Positive terminal is given to the workpiece and Negative terminal is given to the tool.
The tool and workpiece are separated by means of dielectric fluid and an optimum gap is maintained between them.
As stated above, that at normal conditions, the dielectric fluid acts as an insulator. In the sense, no electrical conductivity is taking place.
But, by an increase of high pressure, the dielectric fluid ionizes into Negative and Positive Ions.
The positive ions are attracted towards negative ions and negative ions are attracted towards positive ions and thereby the heat is generated.
When positive and negative ions collide with each other then the spark is generated between the tool and workpiece which can remove the material from the surface of the workpiece.
When there is no Spark in the container, then the dielectric fluid again turns as an insulator.
The same procedure is repeated to remove the material from the surface of the workpiece.
This is the detailed explanation of Electrical Discharge Machining process along with the basic terms and working.
Advantages of EDM:
- The machining process does not depend on the mechanical properties of the workpiece.
- No residual stresses will be generated because no forces are acting.
- The deeper hole is possible to produce (L/D) up to 20.
- Out of all the non-traditional machining methods, EDM is the method with higher Material Removal Rate (MRR).
- Surface finish is better due to melting and vaporization.
Limitations of EDM:
- Workpiece material must be electrically conductive.
- Perfect square corner holes are not possible to produce.
- Hardening of the workpiece is taking place near to the hole.
Applications of EDM:
- It is used for producing hole size less than 0.1 mm
- Used for die sinking or die manufacturing.
- holes in the air brakes or Pneumatic Brakes were done by an electrical discharge machining process.
[Not in Syllabus] of WMP…
Electron Beam Machining Process (EBM):
Electron beam machining also comes under one of those Non-traditional machining methods where highly dedicated accuracy is maintained. The brief explanation of EBM was explained below in a detailed manner.
Electron beam machining Process (EBM)- 19 Points:
The main points which will come across various competitive exams of Electron Beam Machining process are highlighted in a bolded text so that you can grab the points easily from the given material presented below.
- When a very high voltage power supply is given to the electron gun, it is producing very high-velocity electrons in all the directions.
- By using a magnetic lens or the deflector, all these high-velocity electrons are collected and formed like a beam of electrons having the cross-section area less than 0.05-millimeter square.
- When this high-velocity electron beam is impinging onto the workpiece, the kinetic energy of electrons is converted into heat energy.
- Therefore heat is getting generated at the workpiece and by using this heat, the workpiece is getting melting and evaporating i.e. the mechanism is melting and evaporation.
- To avoid the Dispersion of electrons after the magnetic lens, the total setup is kept in a container which is maintained with a perfect vacuum.
- There is no tool used and only electron gun is used which is made by using Germanium crystal type of material.
- Medium: Perfect Vaccum
- Wear Ratio: infinity.
Advantages of EBM:
9. Very very small size holes can be produced.
10. Highly reactive metals can be machined easily because of perfect vacuum is maintained.
11. Heat affected zone will be minimum.
Disadvantages of EBM:
12. Workpiece material must be electrically conductive.
13. Maintaining a perfect vacuum is difficult.
14. Out of all the non-traditional machining methods, electron beam method has the lowest material removal rate.
15. Because the total setup is kept in an enclosure, machining zone can’t be seen by a machine operator.
Applications of EBM:
16. Mainly used for producing holes in the diesel injection nozzles.
17. Also used for producing blind holes, narrow slots etc.in the workpieces.
18. In electron beam machining, if the voltage given to the electron gun is about 60 to 70000 volts, the velocity of electrons produced is reducing, heat generation at the workpiece is reducing.
19. Therefore, the heat generated is sufficient to melt and join the workpiece called an electron beam welding operation.
This is the complete explanation about Electron Beam Machining process in a detailed manner. If you have any doubts, feel free to ask from the comments section.
EDM Project List for Mechanical Engineering Students:
EDM stands for Electric Discharge Machining which uses the mechanism of Melting and Evaporation. The sparking zone is kept in dielectric and at this zone, the pressure falls below atmospheric pressure and sometimes fall below partial pressures of water vapor.
The mechanism associated with EDM is Cavitation or sand erosion. The EDM consists of R-L-C Circuit in which (75-80)% of cycle time, energy is stored and (20-25)% of cycle time, energy is released.
The EDM is famous for higher Material Removal Rate compared with all the Non-Traditional Machining processes.
Considering all these parameters, I had presented the updated list of EDM Project in the field of mechanical engineering.
EDM Project List for Mechanical Engineering Students:
The EDM Project list for Mechanical Engineering students are as follows:
1.Some Experimental Investigation on DIE Steel in Electric discharge Machining with various Parameter and Electrode Process Parameter Optimization of WEDM Process of EN47 Die Steel.
2.An experimental investigation for material removal rate in EDM using tool or graphite, copper and AISI 316.
3.Some investigation of Electrical discharge machining on OHNS steel with a copper and brass electrode to increase the surface finish and reduced heat-affected zone, lead time by varying machine parameter.
4.Experimental Investigation of Machining Parameter for EDM using Various Material with Copper Electrode.
5.Experimental Investigation of Machining Parameter for EDM Using Various Electrode on EN31 Tool Steel
These are the EDM Project for Mechanical Engineering students.
This is the List of EDM Project List for Mechanical Engineering. Hope they are useful to you. Please Hit the Share so that It can reach to many
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