Electron Beam Machining (EBM)

  • Electron Beam Machining (EBM) is a thermal process. Here a steam of high speed electrons impinges on the work surface so that the kinetic energy of electrons is transferred to work producing intense heating.
  • Depending upon the intensity of heating the workpiece can melt and vaporize.
  • The process of heating by electron beam is used for annealing, welding or metal removal.
  • During EBM process very high velocities can be obtained by using enough voltage of 1,50,000 V can produce velocity of 228,478 km/sec and it is focused on 10 – 200 μM diameter. Power density can go up to 6500 billion W/sq.mm. Such a power density can vaporize any substance immediately.
  • Complex contours can be easily machined by maneuvering the electron beam using magnetic deflection coils.
  • To avoid a collision of the accelerating electrons with the air molecules, the process has to be conducted in vacuum. So EBM is not suitable for large work pieces.
  • Process is accomplished with vacuum so no possibility of contamination.
  • No effects on work piece because about 25-50 μm away from machining spot remains at room temperature and so no effects of high temperature on work.
Schematic diagram of Electron Beam Machining process

Schematic diagram of Electron Beam Machining process

MRR in EBM:
Q = area of slot or hole × speed of cutting = A×V
Where power for ‘Q’ MRR is P = C.Q
Where,
C = Specific power consumption
Thermal velocity acquired by an electron of the work material due to electron beam is

ebm thermal velocity

Where, KB = Boltzmann constant
m = mass of one atom of work.
T = rise in temperature

Advantages:

  • Very small size holes can be produced.
  • Surface finish produced is good.
  • Highly reactive metals like Al and Mg can be machined very easily.

Limitations:

  • Material removal rate is very low compared to other unconventional machining processes.
  • Maintaining perfect vacuum is very difficult.
  • The machining process can’t be seen by operator.
  • Workpiece material should be electrically conducting.

Applications:

  • Used for producing very small size holes like holes in diesel injection nozzles, Air brakes etc.
  • Used only for circular holes.
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All Comments

  • Fantastic concentrated summary

    Jacobus Oct 10, 2015 3:59 pm Reply
  • Nice explanation. if we want to make a small machine ebeam for our lab purpose how much the cost. Can you guide us who is making this machine

    Anand Oct 29, 2015 10:06 pm Reply

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