BMP (Class 14 - Class-17) Welding

Class-14
Other Welding Processes…
Dated-08.09.2020
1
Electro-slag Welding
Electro-slag welding (ESW) is a highly
productive, single pass welding process
for thick (25 -300 mm) materials.
• The plates to be welded set up vertically
with a gap of 2-3 cm. Filler wire and flux
are kept in this gap.
• Filler wires are act as electrode. The
wire is continually fed through a
consumable guide tube into the surfaces
of the metal work-pieces.
• An electric arc is created which melts
the flux and thereafter molten flux short
circuits the arc and heat is generated.
• The wire and tube then move up along
the work-piece. Sometime an vibration
or oscillation motion is given to the
work-piece.
• A copper retaining shoe (can be water
cooled if desired) is used to keep cool
the weld between the plates that are
being welded.
Electro-slag welding is used mainly to
join low carbon steel plates of very
thick sections.
Friction Welding
• Solid state welding in which coalescence is achieved by frictional heat combined with pressure
• No filler metal, flux, or shielding gases normally used
• Process yields a narrow HAZ
• Can be used to join dissimilar metals
• Widely used commercial process, amenable to automation and mass production
(1) rotating part, no

contact;
(2) parts brought into
contact to generate
friction heat;
(3) rotation stopped &
axial pressure applied;
(4) weld created
Applications / Limitations of FRW
Applications:
• Shafts and tubular parts
• Automotive, aircraft, farm equipment, petroleum and
natural gas Industry
Limitations:
• At least one of the parts must be rotational
• Flash must usually be removed
• Upsetting reduces the part lengths (which must be taken
into consideration in product design)
Electron beam welding
Advantages:
• Ability to achieve a high depth-to-width ratio in single-pass welding.
• Minimal shrinkage and distortion or low heat affected zone; ability to
weld in heat sensitive components.
• Due to vacuum no impurities in welded zone and strength is almost
similar to base material.
• With high degree of control and repeatability a wide range of
thickness can be welded.
• Permits welding of refractory metals and combinations of many
dissimilar metals.
Limitation:
• High equipment cost
• Work chamber size constraints
• Time delay when welding in vacuum
• X-rays produced during welding
• Rapid solidification rates can cause cracking in some materials
Class-15
Other Welding Processes…
Dated-11.09.2020
8
Laser beam welding
Light Amplification by Stimulated Emission of Radiation
Stimulating & Stimulated Photons have same

wavelength, phase, direction, and polarization
Laser Beam Properties:

– Coherent; Monochromatic
– Low beam divergence; High Focusibility
– Ultra-short pulse duration
– High Power and High Power Density 9
Laser beam welding
High Power Industrial Laser
 CO2 laser
 Nd:YAG laser
 High power diode laser
 Fiber laser Nd:YAG laser
 Excimer laser
Major Parameters:
• Beam power,
• Travers speed,
• Shielding gas,
• Location of focal position
• Beam characteristic.
Laser welding setup

Applications of Laser beam welding:
• electronics industry
• Medical equipment
• Automobiles and aerospace component
Advantages of Laser Welding:
• High welding speed
• Minimal heat affected zones (suitable for heat sensitive components)
• Better mechanical properties due to rapid cooling by LBW.
• Low distortion, no slag or spatter and the process is automated.
• Laser beam can be controlled to a great precision
• Similar and dissimilar metals can be welded
• Remote locations that are difficult to reach by conventional process can be welded
• Thick (>1 inch) single pass welds can be achieved with high power CO2 and Nd:YAG lasers
• Can be automated via fiber optics and robotic arm for welding of complex structure.
Disadvantages of Laser Welding:

• Rapid cooling rate causes cracking in high carbon steels
• High equipment cost
Ultrasonic welding
Applications
• electrical and electronics components
• automotive and aerospace,
• medical, and packaging.
• for bonding thermoplastics.
• It is fast and easily automated with weld
times often below one second.
Class-16
Welding Defects..
Brazing and soldering…
Dated-14.09.2020
13
Welding Defects
1. Cracks
2. Porosity
3. Solid Inclusion
4. Lack of Fusion
5. Inadequate or incomplete penetration

Imperfect Shape
Brazing and Soldering
• Brazing and soldering are the metal joining processes in which parent metal does not melt
but only filler metal melts filling the joint with capillary action.
• If the melting temperature of filler metal more than 450°C but lower than the melting
temperature of components then process known as brazing .
• If the melting temperature of filler metal is lower than 450°C and also lower than the
melting point of the material of components then it is know as soldering.
• During brazing or soldering flux is used to
• Dissolve oxides from the surfaces to be joined.
• Reduce surface tension of molten filler metal or increasing its wetting action.
• Protect the surface from oxidation during joining operation.
• The strength of brazed joint is higher than soldered joint but lower than welded joint.
Class-17
Welding Problems..
Dated-15.09.2020
19
• In case of arc welding heat input P in watts given by P=VI (W or
J/S)
• V is potential of power source in volts, and I is current in
amperes
• During welding since the electrode is moving at a velocity v, the
actual heat available for melting per unit length of the joint is
given by H=P/v (J/mm)
• This is actual heat generated at the tip of the electrode, and
ideally should available for melting the joint. However, actual
heat transfer depends on how this heat is transferred from
electrode tip to weld joint. Accordingly, heat transfer efficiency
f1 can take into account and net heat available at weld joint Hnet
= f1 VI/v J/mm
• For different types of welding f1 varies. (TIG=0.21 to0.48,
SMAW=.66 to .85 SAW=0.9 to 0.99)
• Net heat actually utilized for melting can be obtained by
assuming another efficiency f2
• Melting efficiency f2 = heat required to melt joint/net heat
supplied
Find out welding efficiency

BMP (Class 14 - Class-17) Welding

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Class-14

Other Welding Processes…

(1) rotating part, no

Other Welding Processes…

Stimulating & Stimulated Photons have same

Laser Beam Properties:

Laser welding setup

Disadvantages of Laser Welding:

5. Inadequate or incomplete penetration

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