Electron beam machining utilizes a focused beam of high-velocity electrons to drill and cut materials through melting and vaporization. It involves thermionic emission of electrons from a cathode which are accelerated toward the workpiece. Magnetic and electromagnetic lenses shape and focus the beam for localized heating and material removal. Electron beam machining can drill small holes with high aspect ratios in a wide range of materials at high speeds without mechanical forces. However, it requires expensive equipment and vacuum systems.

1. Electron Beam Machining
11/23/2021
Er.
Mohit
Ostwal
Asst.
Prof.
JIET-
Jodhpur

2. Content
• Introduction
• Equipment/Setup
• Process
• Mechanism of material removal
• How vacuum is created?
• Process capabilities
• Advantages
• Disadvantages
• Application
11/23/2021
Er.
Mohit
Ostwal
Asst.
Prof.
JIET-
Jodhpur

3. Introduction - EBM
• Electron beam machining (EBM) is a thermal material removal
process that utilizes a focused beam of high-velocity electrons to
perform high-speed drilling and cutting.
• The mechanism of material removal is primarily by melting and rapid
vaporization due to intense heating by the electrons
• Also known as “Electro-optical-thermal process”.
• Very high drilling rates are achievable.
• Can machine almost any material.
11/23/2021
Er.
Mohit
Ostwal
Asst.
Prof.
JIET-
Jodhpur

4. Equipment/Setup
High voltage supply to
cathode
Cathode Cartridge
Bias grid
Anode
Port for vacuum
gauge
Diffusion pump
Magnetic Lens
Illuminating
system
Aperture
Telescope
Electromagnetic coils
Deflector coils
Slotted Disc
Er.
Mohit
Ostwal
Asst.
Prof.
JIET-
Jodhpur

5. 11/23/2021
Er.
Mohit
Ostwal
Asst.
Prof.
JIET-
Jodhpur

6. Equipment/Setup
• Cathode Cartridge
• Tungsten/Tantalum
• High voltage is applied
• Thermo-ionic emission
of electrons (Vacuum)-
thermally induced flow
of electrons from
surface.
• Negatively biased –
repel the electrons.
11/23/2021
Er.
Mohit
Ostwal
Asst.
Prof.
JIET-
Jodhpur

7. Equipment/Setup
• Bias Grid
• Highly negatively
biased
• Controls the flow of
electrons.
• To avoid the
divergence of the
electrons and send
them as a beam to the
next step (anode)
11/23/2021
Er.
Mohit
Ostwal
Asst.
Prof.
JIET-
Jodhpur

8. Equipment/Setup
• Anode
• Positively biased
terminal
• Due to the potential
difference b/w
cathode and anode
the electrons
accelerates.
• Velocity is approx.
half the velocity of
light – passing
through anode.
11/23/2021
Er.
Mohit
Ostwal
Asst.
Prof.
JIET-
Jodhpur

9. Equipment/Setup
• Magnetic Lens
• Same function as
that of any lens.
• Concentrates the
beam of electrons.
• Shape the beam.
• Reduce the
divergence of the
beam.
11/23/2021
Er.
Mohit
Ostwal
Asst.
Prof.
JIET-
Jodhpur

10. Equipment/Setup
• Aperture
• Capture the stray
electrons present
near the frame.
• Captured electrons
are then set for
obtaining a
concentrated beam
of electrons.

11. Equipment/Setup
• Electromagnetic
Lens
• Focuses the electron
beam onto the
workpiece.
• On a particular spot.
11/23/2021
Er.
Mohit
Ostwal
Asst.
Prof.
JIET-
Jodhpur
11

12. Equipment/Setup
• Deflector coils
• Deflect the electron
beam by small
amount.
• Correct the beam in
case of not getting
proper hold-ship.
• Improve the shape of
the machined holes.
11/23/2021
Er.
Mohit
Ostwal
Asst.
Prof.
JIET-
Jodhpur

13. Equipment/Setup
• illuminating system
& Telescope
• Both are used
simultaneously to
align the electron
beam with the
workpiece.
11/23/2021
Er.
Mohit
Ostwal
Asst.
Prof.
JIET-
Jodhpur

14. Equipment/Setup
• Slotted Disc
• To avoid obstruction
of vapor of metal
into the optical
window of EBM.
• Allow Electron
beam to pass but not
the vapors/metal
fumes to pass
through it.
• Synchronized with
the pulsed beam.
11/23/2021
Er.
Mohit
Ostwal
Asst.
Prof.
JIET-
Jodhpur

15. Mechanism of material removal
• As high voltage is applied across the Cathode filament , thermo-ionic
emission of electrons takes place.
• These Thermo-ionic electrons are replied by the cathode and attracted by
anode through the bias grid, electrons are accelerated to the half of the
velocity of the light.
• These electron/beam of electron is shaped and focused with the help of series
of magnetic and electromagnetic lenses.
• Finally the electron beam impinges the workpiece.
• Upon impingement the kinetic energy of the electron is absorbed by the
workpiece which will result into heating, melting and vaporization – drilling.
• Spot size – 10 to 100 microns – high energy density
11/23/2021
Er.
Mohit
Ostwal
Asst.
Prof.
JIET-
Jodhpur

16. Mechanism of material removal
Localized heating by
focused electron beam
Gradual formation of hole
Auxiliary
workpiece
Auxiliary
workpiece
W/P W/P
11/23/2021
Er.
Mohit
Ostwal
Asst.
Prof.
JIET-
Jodhpur

17. Mechanism of material removal
Penetration till the
auxiliary support
Removal due to high
vapour pressure
Auxiliary
workpiece
W/P
Auxiliary
workpiece
W/P
11/23/2021
Er.
Mohit
Ostwal
Asst.
Prof.
JIET-
Jodhpur

18. Process capabilities
• EBM can provide holes of diameter in the range of 100 μm to 2 mm with a
depth upto 15 mm.
• Generally burr formation does not occur in EBM.
• A wide range of materials such as steel, stainless steel, Ti and Ni super-alloys,
aluminium as well as plastics, ceramics, leathers can be machined successfully
using electron beam. Typically the heat-affected zone is around 20 to 30 μm.
• Some of the materials like Al and Ti alloys are more readily machined
compared to steel.
• EBM does not apply any cutting force on the work pieces. Thus very simple
work holding is required. This enables machining of fragile and brittle materials
by EBM.
11/23/2021
Er.
Mohit
Ostwal
Asst.
Prof.
JIET-
Jodhpur

19. Advantages
 EBM provides very high drilling rates when small holes with large aspect
ratio are to be drilled.
 Moreover it can machine almost any material irrespective of their mechanical
properties. As it applies no mechanical cutting force, work holding and
fixturing cost is very less.
 Further for the same reason fragile and brittle materials can also be processed.
11/23/2021

20. Disadvantages
 The primary limitations are the high capital cost of the equipment and
necessary regular maintenance applicable for any equipment using
vacuum system.
 Moreover in EBM there is significant amount of non-productive
pump down period for attaining desired vacuum.
11/23/2021
Er.
Mohit
Ostwal
Asst.
Prof.
JIET-
Jodhpur

21. Application
1. Drilling
2. Perforating of sheet
3. Pattern generation.
11/23/2021
Er.
Mohit
Ostwal
Asst.
Prof.
JIET-
Jodhpur

22. 11/23/2021
Er.
Mohit
Ostwal
Asst.
Prof.
JIET-
Jodhpur
22