Unit 4 OTHER WELDING PROCESS (MECHANICAL ELECTIVE COURSE)

Other Welding Process
PR 8592 WELDING TECHNOLOGY
Unit-4 Other Welding Process
Other Welding Process (Vengala kumar P)
P. Vengalakumar ME.MBA.,
TF/MECHANICAL ENGG.,
UNIVERSITY VOC COLLEGE OF ENGINEERING .
VENGALAKUMAR ME MBA 1

Thermit welding
outline
1 Thermit welding
2 Electron beam welding
3 Laser Beam welding
4 Friction stir welding
5 Under Waterwelding
6 Welding Automation In Aerospace Industries
Other Welding Process (Vengala kumar P)VENGALAKUMAR ME MBA 2

Thermit welding
Process of Thermit Welding
Thermit welding is achemical welding processin which an
exothermic chemical reaction is usedto supply the essential heat
energy.That reaction involves the burning of Thermit, which is a
mixture of fine aluminum powder andiron oxide in the ratio of
about 1:3 by weight.
Although atemperature of 3000◦C maybeattained asaresult of
the reaction, preheating of the Thermit mixture up to about
1300◦C is essential in order to start the reaction.

Thermit welding
The mixture reacts according to the chemical reaction:
8Al + 3Fe3O4 − → 9Fe+ 4Al2O3 + heat
(3000◦C, 35 kJ/kg of mixture)
Aluminum has greater affinity to react with oxygen; it reacts with
ferric oxide to liberate pure iron and slag of aluminumoxide.
Aluminum oxide floats on top of molten metal pool in the form of
slag and pure iron (steel) settled below, because of large difference in
densities.

Thermit welding

Thermit welding
Application and Uses
Thermit welding is avery old processandnow-a-days, in most
cases,it is replacedby electro-slag welding. However,this process is
still in use.
Someapplications are:
(i)Thermit welding is traditionally usedfor the welding of very
thick andheavy plates.
(ii)Thermit welding is usedin joining rail roads,pipesand thick
steel sections.

Thermit welding
Application and Uses
(i)Thermit welding is alsousedin repairing heavycastings and
gears.
(ii)Thermit welding is suitable to weld large sections suchas
locomotive rails, ship hulls etc.
(iii) Thermit welding is usedfor welding cablesmadeof copper.

Thermit welding
Advantages
1.Thermit welding is asimple and fast processof joining similar or
dissimilar metals.
2. This processis cheap,asno costly power supply is required.
3.This processcanbeusedat the placeswhere powersupply is
not available.

Thermit welding
Disadvantages
1.Thermit welding is essentially usedfor ferrousmetal parts of
heavy sections.
2. It is uneconomical for welding cheapmetals and lightparts.

Electron beam welding
outline
1 Thermit welding
3 Laser Beamwelding
5 Under Water welding

Electron Beam Welding Principle
 Electron beamwelding in vacuum utilizes the kinetic energyof
electrons traveling with high velocity in ahigh vacuum (10-3 to
10-5 mm Hg). Whenthe electrons strike the surfaceof the
metal,they give up the bulk of their energyasheat, andthis goes
to melt the metal.
 If the work is donein ahigh vacuum, no electrodes, gases,or filler
metals needto contaminate it and pure welds can be
made.Moreover,high vacuum is necessaryaround the filament so
that it will not burn up andwill also produceandfocus astable
beam.This is the basic electron beamwelding workingprinciple.

Electron Beam Welding Working
 In all types of electron beammachines,atungsten filament which
servesasacathode emits amassof electrons that areaccelerated
andfocusedto a0.25 –1mm diameter beamof high energy
density up to 0.5 –10 kW/mm2.
 The temperature producedis about 2,500◦C. This is sufficient to
melt andvaporize thework-piece material andthus tills anarrow
weld gapevenwithout afiller rod (although filler rods maybe
employed).
 The speedof the beamis steppedto one-half to two-thirds of the
speedof light by passingit through ahigh-voltage electrostatic
field. An electromagnetic lensis usedto obtain the correct
focusing of the beam.

Electron Beam Welding

Advantages
The advantagesof electron beamwelding arethat the welds are
1. clean, with no porosity sincethere is no air;no shielding gasis
required.
2. asthe energyinput is in anarrow, concentrated beam,distortion
is almost eliminated.
3. The speedmaybeasfast as 2500 mm per minute, andit will
weld or cut anymetal or ceramic, diamond, sometimesasthick
as150 mm.

Disadvantages
1. Oneof the disadvantagesof the electron beamprocessis its high
capital cost.
2. The price of the equipment is very high, and it is expensiveto
operate, dueto the requirement for vacuum pumps.
3. Fit up must bepreciseand locating the parts with respect to
the beammust beperfect.

Applications
1. Almost all metals can bewelded with the electron beamwelding
process.The metals that aremost often welded aresuper-alloys,
the refractory metals, the reactive metals, andthe stainless
steels.
2. Many combinations of dissimilar metals canalso bewelded.
Today automobile, airplane, aerospace,and other types of
equipment including ball-bearing over 100 mm arebeing welded
by the electron beamwelding process

Laser Beam welding
outline
1 Thermit welding
3 Laser Beamwelding

Laser Beam welding
Laser Beam welding Principle
• Laser Beam Welding is a fusion welding process in which two
metal pieces are joined together by the use of laser. The laser
beams are focused to the cavity between the two metal pieces to
be joined.
• The laser beamshave enoughenergyandwhen it strikes the metal
piecesproduce heat that melts the material from the two metal
piecesandfills the cavity. After cooling astrong weld is formed
between the two pieces.
• It is avery efficient welding processandcan beautomatedwith
robotics machinery easily. This welding techniqueis mostly used
in the automotive industry.

Laser Beam welding
Working Principle
It workson the principle that when electrons of anatom gets excited
by absorbing someenergy.And then after sometime when it returns
back to its ground state, it emits aphoton of light. The
concentration of this emitted photon increased by stimulated
emission of radiation andweget ahigh energyconcentrated laser
beam.
Light amplification by stimulated emission of radiation is called
laser.

Laser Beam welding
Laser Beam welding

Laser Beam welding
Advantages
i. It produces high weld quality. LBW canbeeasilyautomated
with robotic machinery for large volume production.
ii. No electrode is required.
iii. No tool wearsbecauseit is anon-contact process.
iv. The time taken for welding thick section is reduced.
v. It is capableof welding in those areaswhich arenot easily
accessible.
vi. It hasthe ability to weld metals with dissimilar physical
properties.
vii. It can be weld through air and no vacuum is required.

Laser Beam welding
Disadvantages
i. The initial cost is high. The equipment usedin LBW hasa
high cost.
ii. High maintenance cost.
iii. Dueto the rapid rate of cooling, cracksmaybeproducedin
somemetals. High skilled labor is requiredto operate LBW.

Laser Beam welding
Application
i. The laser beamwelding is dominant in the automotive industry.
ii. It is usedin the areawhere large volume production is
required.

Friction stir welding
outline
1 Thermit welding
3 Laser Beamwelding

Introduction
 Friction stir welding (FSW) is asolid-state joining process.
 Solid-state welding meansthat there is no molten state included
in joining or welding the workpiece. This joining technique saves
energyand is eco-friendly. It is mostly usedto weld aluminum
materials in the automobile andaerospace industries.
 The FSW is the processin which atool is usedwhich doesnot
getsconsumedin joining the workpiecesoit is called a
 non-consumable tool. A non-consumablerotating tool with apin
andashoulder is inserted into the adjacent edgesof sheetsor
plates to bejoined andmoved along the line of joint till the end. It
is consideredto bethe most significant development in the metal
joining processand is a“green” technology dueto its energy
efficiency,environment friendliness, etc.

Working Principle
 Firstly clamp the workpiecein aheavy-duty setup, sothat it does
not moveor shakeat the time of welding. Workpieceshould be
abutting i.e. both parts should bekept sideto sideat aparticular
distance from eachother.
 Now insert ablunt or probe tool till the whole pin getsinserted in
the abutting edges.Now the shoulder getsin touch with the
abutting edges.The tool starts rotating within contact with the
job. Dueto contact of the workpiece, friction is applied andasa
result of it, heat is generated.
 This heat makesthe metal plastically melt. Whenthe metal gets
plasticized the high downward forcesor pressuremakesastrong,
cleanand solid-state weld.

Important Welding Parameters
1. Tool Design:
2. Tool Speeds:
3. Tool Tilt:
4. Plunge Depth:

Advantages
1) Mechanical properties of the metal arenot degradedafter the
welding process.
2) There is no production of fumesandunwanted metal spatter of
molten state.
3) In the FSW processsafety level is up to the mark and no risk of
getting hurt.
4) No consumable,no filler metal and no shielding gasis required
in this process.
5) It can beusedin any position i.e.in horizontal, vertical etc.

Limitations
1) The hole which is madebythe blunt probe tool is left unfilled at
the time of exit.
2) Heavy-duty clamping setup is required to hold the workpieceor
job during the welding process.
3) Largedownward forcesarerequiredto get the probe tool get
inserted inside the metal.
4) Many times this welding processis slowerthan manyother
processes.
5) Friction stir welding cannot makeweld joints in which there is
requirement of metal deposition.

Application
1) Usedin shipbuilding companies to weld big parts of the ship.
Mostly usedin aerospaceindustries to join or weld the bigger
parts like wings etc.
2) It is usedin automotive industries to held many parts. Usedin
railways.
3) It is also usedin fabrication work of metals.

Under Water welding
outline
1 Thermit welding
3 Laser Beamwelding

Under Water welding
Under Water welding
The two main categoriesof underwater welding techniques are:
1. Wet underwater welding
2. Dry underwater welding (also called Hyperbaric welding)

Under Water welding
Wet underwater welding
a. In wet underwater welding, shieldedmetal arc welding is
commonly used,employing awaterproof electrode. Other
processesthat are usedinclude flux-cored arc welding and
friction welding.
b. In eachof thesecases,the welding powersupply is connected
to the welding equipment through cables andhoses.
c. The processis generally limited to low carbon equivalent steels,
especially at greaterdepths, becauseof hydrogen-caused
cracking.

Under Water welding
Dry underwater welding
a. In dry underwater welding, the weld is performedat the
prevailing pressurein achamberfilled with agasmixture sealed
around the structure being welded.
b. For this process,gastungsten arc welding is often used,and
the resulting welds aregenerally of highintegrity.
c. The applications of underwater welding arediverse –it is
often usedto repair andconstruct ships, offshoreplatforms,
and pipelines. Steel is the most commonmaterialwelded.
d. In terms of underwater cutting, oxygen-arccutting with
exothermic electrodes andsteel tubular electrodes arealso used

WELDING AUTOMATION IN AEROSPACE INDUSTRIES
●Aerospace manufacturing is unique and specialized.
The parts are complex and often gigantic.
●While it may come as a surprise this industry has
begun to rely more and more on standard 6 axis
industrial robot not specialized machinery.

REASON FOR IMPLEMENTATION OF WELDING ROBOTS IN
AEROSPACE INDUSTRIES
● Robotics automation is economical.
● Usability and robotics automation.
● Flexible automation with 6 axis robot.
● Robotics automation and the aerospace worker.
37

ROBOTICS AUTOMATION IS ECONOMICAL
●Aerospace manufacturers are attracted to
robots cost effectiveness.
●The typical 6 axis articulated robot is far
more affordable than custom-built machine
and it perform just as effectively.
38

USABILITY AND ROBOTICS AUTOMATION
●Compared to setting up customized
machines, robotics automation is easy to
deploy 6 axis robots are quick to setup,
program andput into production.
39

FLEXIBLE AUTOMATION WITH AXIS ROBOT
●Robots are weld suited for aerospace
manufacturing because they offer
application and work envelope flexibility.
●Aerospace production is different than
automotive part production.
40

ROBOTICS AUTOMATION AND THE AEROSPACE WORKER
●Without assistance of industrial robot., aerospace
worker similar to automotive worker must ensure
repetitive welding, debuting and other tasks.
41

AUTOMATION ROBOTIC WELDING SYSTEM
●There are number of different configuration
of automated robotic welding system exist.
●Most of the system have some basic
principle of operation and they have many
elements in common.
●One such a system called parallel
mutisensor system.
42

COMPONENTS OF AUTOMATED ROBOTIC WELDING SYSTEM
● Sensor guided welding cell.
● Welding joint sensor.
● Data Acquisition system.
● Sensor system for robot non linear control.
● Manipulator.
● Multi sensor integration.
43

ROBOTS AND ITS CONTROLLER
●The robot is typically comprised of large number of
links and linkages which are interconnected by
gears, chains, belts and screws.
●The majority of industrial robots are actuated by
linear, pneumatic, hydraulic actuators or electric
device(AC or DC motors).
44

FEATURES OF AUTOMATION IN AEROSPACE INDUSTRY
●Welding in the aerobatic industries is experiencing exciting
developments.
●The application of computers and improved knowledge
and design of new metals are shaping the way welding
implemented for process and product design.
45

ADVANTAGES OF AUTOMATION WELDING
●Increased productivity.
●Consistent weld quality.
●Predictable welding production rate.
●Reduced variable welding cost.
●Lower part cost.
46

LIMITATIONS OF AUTOMATED WELDING
●It needs higher capital investment then for
manual welding equipment.
●A need for more accurate part location and
orientation are required.
●Maintenance cost is more.
47

Comparison of Underwater Welding Over Normal Air Welding
 Electrodes are painted for waterproofing.
 Electrode core wire is usually similar to air welding but
for high strength steel, a core wire of stainless steel or
special steel is required.
 Waterproofed flux coated or iron-oxide covered
electrodes are used in underwater welding.
 The gap between electrode and work is not maintained
in underwater welding because the electrode is lifted
due to the pressure of water during arc but the gap is
maintained between electrode and work in air welding.
48VENGALAKUMAR ME MBA

Unit 4 OTHER WELDING PROCESS (MECHANICAL ELECTIVE COURSE)

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