Electron Beam Welding is a fusion welding process in which a beam of high-velocity electrons is applied to the material to be joined. The work-piece melt as the kinetic energy of the electrons is transformed into heat upon impact. The EBW process is well-positioned to provide industries with highest quality welds and machine designs that have proven to be adaptable to specific welding tasks and production environments.
1. ELECTRON BEAM WELDING
Submitted by:
Ankit Saxena
PGMSE-136013
Submitted to:
Mr Harish Arya
2. Introduction
i. Electron Beam Welding is a
fusion welding process in
which a beam of high-velocity
electrons is applied to the
material to be joined.
ii. The work-piece melt as the
kinetic energy of the electrons
is transformed into heat upon
impact.
iii. The EBW process is well-positioned
to provide
industries with highest quality
welds and machine designs
that have proven to be
adaptable to specific welding
tasks and production
environments.
Fig.1: Key hole penetration in EBW
3.
4. Electron Beam?
i. In an electron beam
welder electrons are
“boiled off” as current
passes through filament
which is in a vacuum
enclosure.
ii. An electrostatic field,
generated by a negatively
charged filament and bias
cup and a positively
charged anode, accelerates
the electrons to about
50% to 80% of the speed
of light and shapes them
into a Beam.
Fig 2:Electron beam source for EB
disposal
5. How does the Process Work?
i. The electron beam gun has a tungsten
filament which is heated, freeing
electrons.
ii. The electrons are accelerated from the
source with high voltage potential
between a cathode and anode.
iii. The stream of electrons then pass
through a hole in the anode. The beam
is directed by magnetic forces of
focusing and deflecting coils.
iv. This beam is directed out of the gun
column and strikes the work piece. The
potential energy of the electrons is
transferred to heat upon impact of the
work piece and cuts a perfect hole at
the weld joint. Molten metal fills in
behind the beam, creating a deep
finished weld.
6. Steps Used in EBW process
Joint preparation.
Cleaning of work piece.
Fixturing of work piece.
De-magnetization of work piece.
Setting up work piece in chamber.
Pump down air form chamber.
Carry welding process.
7. Classification of EBWMachines
• High voltage
machine (U =150
kV)
• Low voltage
machine
(U=60kV)
By Accelerating
Voltage
• High vacuum
machine
• Fine vacuum
machine
• Atmospheric
machine (NV-EB
welding)
By pressure
• Conveyor machine
• Clock system
• All-purpose EBW
machine
• Local vacuum
machine
• Mobile vacuum
machine
• Micro and fine
welding machine
By Machine
concept
11. Comparison with different welding techniques
on the basis of Parameter
PARAMETER TIG PLASMA LASER EB
Power input to
W-P
2kW 4kW 4kW 5kW
Total power
used
3kW 6kW 50kW 6kW
Traverse speed 2mm/s 5.7mm/s 16mm/s 40mm/s
Positional
welding
Good
penetration
Good
penetration
Yes Require
optics to move
the beam
Requires
mechanism to
move the beam
Distortion
shrinkage
Nominal
significant in V-shaped
weld
Nominal
significant in V-shaped
weld
Small
Minimum
Minimum
Minimum
12. PARAMETER TIG PLASMA LASER EB
Special
process
requirement
Normal light
screening
Normal light
screening
Safety
interlock
against
misplaced
beam
reflection
Vacuum
chamber-ray
screen
Surface
geometry
Underside
protrusion
Underside
protrusion
Very fine
ripples
Ruffled swarf
on back face
14. i. EBW is suitable for a variety of difficult applications, such as welding
structures on which the reverse side of the butt is inaccessible ; gravity
welding of thin metal ; and welding in various spatial positions.
ii. This Provides a low level of over all heating of the structures ; and has the
ability to vacuumed the inner volume simultaneously, which is suitable for
sealing instruments. Because EBW is an automated process , the welded joint
quality is consistent .
iii. The process does not require shielding gases , tungsten electrodes , or edge
preparation for welding thick metal .
iv. Finally , it can be used to weld some joints that cannot be made by other
welding processes.
15. v. Compared with arc welding
processes, EBW improves joint
strength 15 per cent to 25 per
cent.
vi. It has a narrow heat-affected
zone(HAZ), which results in
lighter-weight products.
vii. Geometric shapes and dimensions
are highly stable, particularly
when it is used as a finish
operation.
viii. It eliminates oxide and tungsten
inclusion sand removes impurities.
ix. The weld metal has a fine
crystalline structure.
16. Graph showing areas of different welding processes on the plot of
feature size v/s power density.
17. Advantage of EBW
In Vacuum
a) Thin and thick plate welding (0,1 mm bis 300 mm).
b) Extremely narrow seams (t:b = 50:1).
c) Low overall heat input => low distortion =>Welding of completely processed
components.
d) High welding speed possible.
e) No shielding gas required.
f) High process and plant efficiency.
g) Material dependence, often the only welding method.
At atmosphere
a) Very high welding velocity.
b) Good gap bridging. No problems with reflection during energy entry into work
piece.
18. Disadvantage of EBW
In Vacuum
• Electrical conductivity of materials is required.
• High cooling rates => hardening => cracks.
• High precision of seam preparation.
• Beam may be deflected by magnetism.
• X-ray formation.
• Size of work piece limited by chamber size.
• High investment.
At Atmosphere
• X-ray formation.
• Limited sheet thickness (max. 10 mm).
• High investment.
• Small working distance.
19. Field of Application
Industrial areas
• Automotive industries
• Aircraft and space industries
• Mechanical engineering
• Tool construction
• Nuclear power industries
• Power plants
• Fine mechanics and electrical
• Industries
• Job shop
20. Material
• Almost all steels.
• Aluminium and its alloys.
• Magnesium alloys.
• Copper and its alloys.
• Titanium.
• Tungsten.
• Gold.
• Material combinations (e.g. Cu-steel, bronze-steel).
• Ceramics (electrically conductive).