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7/31/2019 Welding Classification
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WELDING
BY
T.MOHAN REDDY,SM(FQA)
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WELDING PROCESS
WELDING PROCESS
SOLID PHASE FUSION WELDING
JOINING BELOW MELTING POINTJOINING AT BEYOND MELTINGPOINT
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SOLID PHASE WELDING
FRICTION WELDING
FLASH BUTT WELDING
EXPLOSIVE WELDING DIFFSION WELDING
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FRICTION WELDING
What Is Friction Welding?
Friction Welding is a completelymechanical solid phase process in whichheat is generated by friction to produce ahigh integrity welded joint between similaror dissimilar metals.
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ADVANTAGES
The advantages are both metallurgical and physical. A bonded jointis formed using no filler metal, flux or shield gas. The process isenvironmentally clean; no arcs, sparks, smoke or flames aregenerated by clean parts. Surface preparation/cleanliness is notsignificant with most materials since the process burns through anddisplaces surface impurities. During the friction welding process
there are narrow heat affected zones. The process is suitable forwelding most engineering materials and is well suited for joiningmany dissimilar combinations. In most cases, the weld strength is asstrong or stronger than the weaker of the two materials being joined.Operators are not required to have manual welding skills. Frictionwelding requires only simple integration into the manufacturing area.The process is easily automated for mass production. Welds aremade rapidly compared to other welding processes. Plantrequirements (space, power, special foundation etc.) are minimal forthe friction welding process.
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TYPICAL APPLICATIONS
ENGINE VALVES
TRANSMISSION DRIVE SHAFTS
DRILL RODS
HYDRAULIC CYLINDERS
FILTER CATRIDGES
DRILL BITS
ELECTRICAL CONNECTORS
VIHICLE AIR BAGS
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FLASHBUTT WELDING
Flash Butt Welding, also known as Flash Welding,uses an arc between the two mating parts as theybegin to make contact. It is commonly used to joinsimilar or dissimilar metals for end-to-end or edge-
to-edge welds. The electrical resistance at the joint raises the
temperature and plastic deformation forms the finalweld. Impurities and contaminants are squeezed outduring this operation resulting in an excellent weld,
but a significant amount of material may be burnt offduring the process. The joint may be machined laterfor improved appearance.
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EXPLOSIVE WELDING
Explosion welding or bonding is a solid statewelding process that is used for the metallurgical
joining of dissimilar metals. The process usesthe forces of controlled detonations to accelerate
one metal plate into another creating an atomicbond. Explosion bonding can introduce thin,diffusion inhibiting interlayers such as tantalumand titanium, which allow conventional weld-upinstallation. Also explosive welding is
considered a cold-welding process which allowsmetals to be joined without losing their pre-bonded properties.
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APPLICATIONS
Dissimilar metal explosion bonded joints are appliedanywhere a designer needs to make a high-qualitytransition between metals. Typical uses includeultra-high vacuum joints between aluminum, copper
and stainless steel, corrosion resistant claddings onmild steel substrates, and alloy aluminum joined tolow-expansion rate metals for electronic packages.Powder metal products such as Glidcop and Al-SiC can be joined to wrought metal without thermal
excursions. Difficult metals such as beryllium, Al-Bealloys and rhenium can be joined with explosionbonding.
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DIFFUSION WELDING
DW, as a special technology, forms a contact on base ofspecial bonding mechanism between metal and substrate. DWis the newest technology compared to standard (sputtering,evaporation, soldering) technologies for manufacturing of highquality contacts, especially on large areas
The DW process has many advantageous, of which veryimportant are: one-step high temperature process formanufacturing multi-layer contacts (low energy process); extrahigh adhesion between layers to be joined; minimum number ofin homogeneities on large area (near defect free contacts); andthe technology improves significantly the certain electricalcharacteristics of manufactured semiconductor devices
compared to other technologies
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For formation of a bonding contact (DWtechnology), three major steps have to be made:
To prepare suitable wafers and metal or ceramic
films into one sandwich; To put the sandwich into a cassette and to
transport it into the vacuum chamber;
To apply a prescribed pressure for a certain time
onto sandwich to promote a penetration ofatoms of each material into neighbour layer(film) for getting extra high quality contacts
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The DW technology is: One step high temperature process, which takes
place in vacuum under mechanical pressure.Temperature does not exceed 500-600 Celsiusdegrees by the pressure about. 50 MPa and themanufacturing time are approximately from 5 to 10minutes;
The lateral homogeneity of the contact area will behigher compared to contacts manufactured byconventional deposited methods, which decreasesthe probability of hot spot creation in the contactduring the device operation.
The DW technology has been shown itself as a veryeffective method by manufacturing the high qualitycontacts to Si, GaAs, SiC, and other materials aswell.
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FUSION WELDING
OXY-ACETELENE GAS WELDING(100WATTS, 3500 C)
ARC WELDING (1000 WATTS, 6000 C)
ELECTRONIC BEAM WELDING(1,00,000 WATTS, 10000 C)
LASER BEAM WELDING (10000 WATTS,10000 C)
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OXYACETYLENE WELDING
Oxyacetylene welding, commonly referred to asgas welding, is a process which relies oncombustion of oxygen and acetylene. When
mixed together in correct proportions within ahand-held torch or blowpipe, a relatively hotflame is produced with a temperature of about3,200 deg.C. The chemical action of the
oxyacetylene flame can be adjusted by changingthe ratio of the volume of oxygen to acetylene.
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PROCESS
Welding is generally carried out using the neutralflame setting which has equal quantities of oxygenand acetylene. The oxidising flame is obtained byincreasing just the oxygen flow rate while the
carburising flame is achieved by increasingacetylene flow in relation to oxygen flow. Becausesteel melts at a temperature above 1,500 deg.C, themixture of oxygen and acetylene is used as it is theonly gas combination with enough heat to weld
steel. However, other gases such as propane,hydrogen and coal gas can be used for joining lowermelting point non-ferrous metals, and for brazingand silver soldering
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EQUIPMENT
Oxyacetylene equipment is portable and easy to use.It comprises oxygen and acetylene gases storedunder pressure in steel cylinders. The cylinders arefitted with regulators and flexible hoses which leadto the blowpipe. Specially designed safety devices
such as flame traps are fitted between the hoses andthe cylinder regulators. The flame trap preventsflames generated by a 'flashback' from reaching thecylinders; principal causes of flashbacks are thefailure to purge the hoses and overheating of the
blowpipe nozzle. When welding, the operator mustwear protective clothing and tinted colouredgoggles. As the flame is less intense than an arc andvery little UV is emitted, general-purpose tintedgoggles provide sufficient protection.
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ELECTRON BEAM WELDING
Electron Beam Welding (EBW) is a fusion joining process thatproduces a weld by impinging a beam of high energy electronsto heat the weld joint. Electrons are elementary atomicparticles characterized by a negative charge and an extremelysmall mass. Raising electrons to a high energy state byaccelerating them to roughly 30 to 70 percent of the speed of
light provides the energy to heat the weld. An EBW gun functions similarly to a TV picture tube. The
major difference is that a TV picture tube continuously scansthe surface of a luminescent screen using a low intensityelectron beam to produce a picture. An EBW gun uses a highintensity electron beam to target a weld joint. The weld joint
converts the electron beam to the heat input required to make afusion weld.
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ELECTRON BEAM WELDING
The electron beam is always generated ina high vacuum. The use of speciallydesigned orifices separating a series of
chambers at various levels of vacuumpermits welding in medium andnonvacuum conditions. Although, high
vacuum welding will provide maximumpurity and high depth to width ratio welds
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ADVANTAGES
Single pass welding of thick joints
Hermetic seals of components retaining avacuum
Low distortion Low contamination in vacuum
Weld zone is narrow
Heat affected zone is narrow
Dissimilar metal welds of some metals
Uses no filler metal
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LIMITATIONS
High equipment cost
Work chamber size constraints
Time delay when welding in vacuum High weld preparation costs
X-rays produced during welding
Rapid solidification rates can causecracking in some materials
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ARC WELDING
ARC WELDING
FLUX SHIELDED(FSAW)
GAS SHIELDED(GSAW)
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GAS SHIELDED ARC WELDING
GSAW
GTAW(GAS TUNGSTON ARC)NON-CONSUMABLE
GMAW(GAS METAL ARC)CONSUMABLE
TIG WELDING PLASMA WELDINGMIG
(METAL INERT GAS)NON-FERROUS
MAG(METAL ACTIVE GAS0
FERROUS
ARGON,HELIUM
CO2,CO2+ARGONO2+ARGON
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GTAW
TIG Welding (GTAW or Gas TungstenArc) - Often called TIG welding (TungstenInert Gas), this welding process joins
metals by heating them with a tungstenelectrode which should not become part ofthe completed weld. Filler metal issometimes used and argon inert gas or
inert gas mixtures are used for shielding.Consumables: tungsten electrode, fillermetal, shielding gas.
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GAS METAL ARC WELDING
MIG (GMAW or Gas Metal Arc Welding) - An arcwelding process which joins metals by heating themwith an arc. The arc is between a continuously fedfiller metal (consumable) electrode and theworkpiece. Externally supplied gas or gas mixtures
provide shielding. Common MIG welding is alsoreferred to as short circuit transfer. Metal isdeposited only when the wire actually touches thework. No metal is transferred across the arc. Anothermethod of MIG welding, spray transfer moves a
stream of tiny molten droplets across the arc fromthe electrode to the weld puddle. Consumables:contact tips, shielding gas, welding wire.
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FLUX SHIELDED ARC WELDING
FLUX SHIELDED ARC
SHIELDED METAL ARC SUBMERGED ARC FLUX CORED ARC
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FLUX CORED ARC WELDING
Flux Cored Arc Welding (FCAW)- An arc weldingprocess which melts and joins metals by heatingthem with an arc between a continuous, consumableelectrode wire and the work. Shielding is obtained
from a flux contained within the electrode core.Depending upon the type of flux-cored wire, addedshielding may or may not be provided fromexternally supplied gas or gas mixture.Consumables: contact tips, flux cored wire,
shielding gas (if required, depends on wire type).
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SAW
Submerged Arc Welding Submerged arc welding (SAW) is a high quality,
very high deposition rate weldingprocess. Submerged arc welding is a high
deposition rate welding process commonly usedto join plate.
Submerged Arc Welding Benefits Extremely high deposition rates possible
High quality welds Easily automated Low operator skill required
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SMAW
Stick Welding Shielded Metal Arc Welding (SMAW) is
frequently referred to as stick or coveredelectrode welding. Stick welding is among the
most widely used welding processes. The fluxcovering the electrode melts duringwelding. This forms the gas and slag to shieldthe arc and molten weld pool. The slag must bechipped off the weld bead after welding. The fluxalso provides a method of adding scavengers,deoxidizers, and alloying elements to the weldmetal.
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SMAW
Stick Welding Benefits
Equipment used is simple, inexpensive,and portable
Electrode provides and regulates its ownflux
Lower sensitivity to wind and drafts thangas shielded welding processes
All position capability
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THANK YOU