WELCOME YOU FOR THE TOPIC ON: by: C B Singh SCIENCE & TECHNOLOGY OF WELDING
It is needless to emphasize that the welding has become, now, the most efficient, economical & popular means of joining materials; Because: <ul><li>It enables act as one . </li></ul><ul><li>It improves strength. </li></ul><ul><li>Reduces the over-all weight. </li></ul><ul><li>Reduces labor time & the cost. </li></ul>
WELDING Definition : A localized coalescence of material with or without the use of filler and also with or without the application of pressure. or Bringing two perfectly smooth & clean material surfaces to an intimate contact, which is an atomic distance, indeed, between the two, is known as welding.
WELDING Fusion Diffusion Pressure Non-pressure * Soldering < 427 0 C * Brazing > 427 0 C * Braze-welding & * R esistance welding * Explosive welding * Forge welding * Friction/Inertia welding * Ultrasonic welding * Cold welding * Thermit welding * Pressure gas welding * Oxy-Fuel gas welding * Electric Arc welding * Plasma Arc welding * Electron Beam welding * Laser Beam welding * Electro Slag / Gas welding
BRAZING & SOLDERING Brazing & Soldering : Low temp. Brazing 450-850 0 C Medium temp. Brazing 850-950 0 C High temp. Brazing > 950 0 C There is no bead formation, but only with capillary attraction.& diffusion. Low temp. Soldering 427 0 C Max .
BRAZE WELDING Braze welding: There is a bead formation, but without the fusion & capillary attraction. An age-old joining technique
OPERATION– Manual/ mechanized/ auto. ADVANTAGE – Usually no distortion & heat damages; easy adaptability for the mass production of several intricate component parts. TYPICAL APPLICATIONS – Repair & maintenance, tool-tips, heat-exchangers, electrical switches, electric motor parts, gas turbine parts, bicycle frames, utensils & kitchen-wares etc. BRAZE WELDING, BRAZING & SOLDERING
An age-old metal joining techniques: BRAZING & SOLDERING
THERMIT WELDING (TW) Thermit Powder Molten Crucible RAILS Mould Igniter Molten metal flows down developed in 1893 Flame heating gate Thermit powder: Fe 2 O 3 + 2Al = 2Fe + Al 2 O 3
THERMIT WELDING (TW) OPERATION – Manual skill . TYPICAL APPLICATIONS – Confined to the railway tracks only, but can also be used for reinforced concrete bars & copper conductors & e asy to use on site . LIMITATIONS – Limited range of joints and materials., difficult to ensure consistency in it’s weld quality, slow & expansive, require a group of five people to work in tandem.
Oxy-Acetylene Gas Filler Rod Gas Flame Weld Bead OXY- FUEL GAS WELDING (OFW) developed in 1904
OPERATION – Manual skill. ADVANTAGE – No power supply needed, low investment, highly - portable, excellent performance on Cast-iron, Cast-steel, depositing Tungsten-carbide & Stellite for hard surfacing. TYPICAL APPLICATIONS – Repair & reclamation welding of motor vehicle parts, sheet metal & light fabrication welding. OXY- FUEL GAS WELDING
CARBON/AIR ARC GOUGING (CAG) 1. Power source 2. Holder cable 3. Earth cable 4. Work 5. Carbon electrode & 6. Compressed Air.
SHIELDED METAL ARC WELDING (SMAW) _ + _ 1 . Power source 2. Holder cable 3. Earth cable 4. Work & 5. Electrode developed in 1907 MANUAL METAL ARC WELDING (MMAW)
OPERATION – Manual skill . ADVANTAGE – Low capital investment, wide variety of application even in restricted areas. TYPICAL APPLICATIONS – Ship building, Structural steel work, High-rise Buildings, Locomotive, Rail-road, Armament, Automotive, Transmission Pipeline, Mining, Repair & Construction of plant and machinery of all types. It is used for joining, rebuilding & hard-surfacing. SHIELDED METAL ARC WELDING (SMAW) MANUAL METAL ARC WELDING (MMAW)
An arch-bridge on river Chenab in Kashmir by Konkan Rly, Usage 26,000 Tons of steel, 1.3K.M. long & 359 M high > Affil tower (324M) This will be the tallest bridge made within 30Months Ref: www.bbchindi.com – dated 17 th , Apr, 2006
Mechanized wire feed Mechanized arc tracking SUBMERGED ARC WELDER (SAW) Granulated SAW flux developed in 1936
SUBMERGED ARC WELDER (SAW) OPERATION – Usually mechanized or automatic . ADVANTAGE – High deposition rate, high quality radiographic sound weld, invisible arc underneath the flux granules causes least fatigue to the operator. TYPICAL APPLICATIONS – High quality pressure vessel, c hemical plant, s hip building, structural engineering component parts, and also for rebuilding & surfacing.
Mechanized wire feed FCAW - with or without external gas shield Flux Cored Electrode FLUX CORED ARC WELDING (FCAW) developed in 1955
OPERATION – Usually semi-automatic but also mechanized or automated, if the need arises . ADVANTAGE – High deposition rate, high quality weld for shop & site welding, it causes lesser fatigue than GMAW to the welder. TYPICAL APPLICATIONS – Pressure vessel, chemical plant, pipe work, structural work, ship building, and also popular for rebuilding & surfacing on shop and site. FLUX CORED ARC WELDING (FCAW)
GAS-SHIELDED METAL ARC WELDING (GMAW) GMAW , SIGMA, MIG/MAG or CO 2 /MIG Welding Mechanized wire feeding Consumable Electrode Inert/active gas feed MIG developed in 1950 & MAG welding during 1953
GAS-SHIELDED METAL ARC WELDING (GMAW) OPERATION– Usually semi-automatic but also mechanized or robotic . ADVANTAGE – Continuous process with reduced finishing operation, high quality weld including in vertical down with extra low hydrogen. TYPICAL APPLICATIONS – Light, m edium & heavy fabrication such as ship-containers, light and heavy vehicle, earth movers, heavy machinery fabrication etc.
Filler Rod H 2 gas Tungsten Electrodes ~ ~ ATOMIC HYDROGEN WELDING (AHW) developed in around 1940, but it was made to disappeare soon OPERATION – Usually manual but also mechanized. ADVANTAGE – Similar to those of GTAW process. TYPICAL APPLICATIONS – Welds in thin materials particularly stainless steel; mechanized thin sheet welding .
GTAW / TIG Welding Inert gas feed Filler rod Non-consumable Tungsten Electrode GAS-SHIELDED TUNGSTEN ARC WELDING (GTAW) developed in 1942
OPERATION – Usually manual but also scarcely mechanized for tube to tube sheet & orbital welding . ADVANTAGE – Wide range of metals, produces high quality standard weld with extra low hydrogen. TYPICAL APPLICATIONS – High quality weld in stainless steel for nuclear reactors, chemical & fertilizer plants, industrial piping, nickel alloys for aircraft engines, aluminum alloys for food industry. GAS-SHIELDED TUNGSTEN ARC WELDING (GTAW)
PAW Filler rod Plasma gas Shielding Gas PLASMA ARC WELDING (PAW) + developed in 1959
PLASMA ARC WELDING (PAW) OPERATION – Usually mechanized . ADVANTAGE – Wide range of metals, produces high quality deep penetration weld with extra low hydrogen. TYPICAL APPLICATIONS – High quality weld in stainless steel sheet foil butt welds, electronics cans, thermo couples, bellows, capsuls, filters by MPW and high speed tube manufacturing, high speed unprepared butt joint making in chemical plant.
E.B.W. Gun Beam alignment coil Optics Vacuum Chamber Deflection Coil Focus Coil Work ELECTRON BEAM WELDER (EBW) developed in 1960
OPERATION – Fully mechanized . ADVANTAGE – Excellent penetration; Low distortion; Non-contaminated weld; High speed welding; Ability to weld several non-weld-able materials. Any metal may be welded compatible with the vacuum while in molten state. TYPICAL APPLICATIONS – Gear clusters/shafts joint; Turbine blade root joint; Fully mechanized. ELECTRON BEAM WELDER (EBW)
LASER BEAM WELDER (LBW) Capacitor Bank Flash tube Focusing lens Work Laser beam developed in 1967 OPERATION: Fully mechanized . ADVANTAGE: Wide range of materials . TYPICAL APPLICATIONS: Continuous laser for the develop-mental activities; Pulsed laser for reputed application to some small assemblies such as electronic component parts.
ELECTRO SLAG WELDER (ESW) Electrode wire Copper shoe Weld metal Work Developed in 1956 OPERATION– Mechanized only . ADVANTAGE – Fast completion of thick joint in singular run. TYPICAL APPLICATIONS – Thick wall pressure vessels; Thick civil engineering & structural fabric-ation work and Ship-building.
COLD WELDING (CW) Split die Split die ADVANTAGE – Large area of weld made in high conducting materials such as copper and aluminum; Low cost welding. TYPICAL APPLICATIONS: Welding of copper overhead conductors for electric traction; Aluminum - copper joints for electric cables.
FORGE WELDING (FOW) Force An age-old welding technique
FORGE WELDING (FOW) TECHNIQUE – Pressure welding . OPERATION – Manual or mechanized . APPLICATION – Black-smith’s artistic iron ware only; dimensions not easily controlled and difficult to assure quality. Limited low carbon & some alloy steels only.
~ ~ ELECTRIC RESISTANCE SPOT WELDER (ERW) Developed in 1887
OPERATION – Mechanized or robotized . ADVANTAGE – Consumable & skill is not required thus consistent weld quality with high productivity. Commonly used ferrous & non-ferrous metals but difficult to weld copper. TYPICAL APPLICATIONS – Light fabrication from pressed sheet parts such as motor vehicle bodies, domestic washing machines, and cabinets for refrigerators etc. ELECTRIC RESISTANCE SPOT WELDER (ERW)
PROJECTION SPOT WELDER (RPW) ~ ~ Step-1 Step-2 Ideal for making multiple spots, where the spacing may be the designers constraint.
FRICTION WELDER (FRW) Developed in 1955 OPERATION – Mechanized . ADVANTAGE – Produces consistently high quality welds; Fast joining of large area; Suitable for wide range of materials; Mechanized & works on simple principle; & Consumable is not required. TYPICAL APPLICATIONS – Internal combustion engin valves; Head to stem joint of dissimilar metals; Stud welding; Rear axle casings; Transmission and steering components for vehicles and Electrical part connections .
EXPLOSIVE WELDING (EXW) Flyer plate Explo-sive Buffer APPLICATIONS – Manufacture of steel to aluminum or copper transition pieces for fabrication; Cladding steel parent plate; Tube - to -tube sheet joints. The wide range of metals studied to date give good results The process is particularly suited to dissimilar metals. ADVANTAGE –Cladding large plates without preheat; Suitable for wide range of dissimilar metals; Fast as a large area is joined in single shot.
PROCESSES & THEIR LETTER DESIGNATIONS LETTER DESIGNATION WELDING PROCESS GROUP Arc welding Carbon Arc Flux Cored Arc Gas Metal Arc Gas Tungsten Arc Plasma Arc Shielded Metal Arc Stud Arc Submerged Arc CAW FCAW GMAW GTAW PAW SMAW SW SAW Brazing Diffusion Brazing Dip Brazing Furnace Brazing Induction Brazing Infrared Brazing Resistance Brazing Torch Brazing DFB DB FB IB IRB RB TB Continued …
Oxyfuel Gas Welding Oxyacetylene Welding Oxyhydrogen Welding Pressure Gas Welding OAW OHW PGW Resistance Welding Flash Welding High Frequency Resistance Percussion Welding Projection Welding Resistance-Seam Welding Resistance-Spot Welding Upset Welding FW HFRW PEW RPW RSEW RSW UW Solid State Welding Cold Welding Diffusion Welding Explosion Welding Forge Welding Friction Welding Hot Pressure Welding Roll Welding Ultrasonic Welding CW DFW EXW FOW FRW HPW ROW USW PROCESSES & THEIR LETTER DESIGNATIONS
Soldering Other Welding Processes Dip Soldering Furnace Soldering Induction Soldering Infrared Soldering Iron Soldering Resistance Soldering Torch Soldering Wave Soldering DS FS IS IRS INS RS TS WS Electron Beam Welding Electro Slag Welding Induction Welding Laser Beam Welding Thermit Welding EBW ESW IW LBW TW PROCESSES & THEIR LETTER DESIGNATIONS Ref: AWS