Post on 25-Dec-2015
1
2008 Design amp ManufacturingII
Spring 2004
Welding amp Joining
2008-spring-2004SKim
2
Today
Ask ldquoDave and Patrdquo1048708 Joining amp Welding1048708 PP 771-861 Kalpakjian1048708 Quiz 1 on March 17th 1230 PM1048708 Closed book calculator1048708 Lecture notes HWs1048708 QampA session March 15th Monday 5-6PM 1048708 HW 4 due next Monday
2008-spring-2004 SKim
3
Joining
1048708 Cost1048708 Cheap but expensive labor
1048708 Quality1048708 Wide range
1048708 Flexibility1048708 Manual vs automated
1048708 Rate1048708 Slow in genera
Very Large Crude Carrier (VLCC)
2008-spring-2004 SKim
4
Joining processes
engine fasteners door
Mechanical nutsbolts
rivets c-clips pressure fits
Solid-liquid Adhesives
Soldering Brazing
Solid Friction Diffusion Explosion Ultrasound
Liquid
Chemical Oxyfuel Thermit
ECUS emission controller windshield plastic fans
Body muffler
Resistance Spot Seam Flash
door hingesConsumable electrode Shielded metal arc Submerged arc Gas metal arc
nonConsumable electrodeGas Tungsten Plasma Arc Electron Beam Laser welding
Arc Welding
2008-spring-2004 SKim
5
Mechanical Fastening
1048708 Any shape and material almost1048708 Disassemblable (except Rivets etc)1048708 Least expensive for low volume (standardized)1048708 Problems strength seal insertion loosening
Threaded Bolted Rivets Snap fit
Figures B Benhabib2008-spring-2004 SKim
6
Rivets
1048708 Cheap light weight donrsquot get loose1048708 Permanent less strong than bolts1048708 Rule of thumb1048708 Minimum spacing = 3 x d1048708 Maximum spacing = 16 x thickness of the outer plate
Rivets
2008-spring-2004 SKim
7
Mechanical fastening
1048708 Crimping1048708 Embossed protrusions1048708 Plastic deformation interference1048708 Appliance1048708 Automotive
Lego assembly elastic averaging
M Culpepper MIT2008-spring-2004 SKim
8
Mechanical Joining
1048708 Hemming seaming1048708 Bend edge of one component over another1048708 Automobile door stampings and trunk lids
2008-spring-2004 SKim
9
Adhesive Bonding
1048708 Quick and non-invasive1048708 Most materials with high surface to volume ratio1048708 Insulation (thermal electrical) conducting adhesives available1048708 Good damping1048708 Clean surface preparation1048708 Long curing hold time low service T1048708 Reliability quality1048708 Disassembly
2008-spring-2004 SKim
10
Stefan Equation
1048708 Squeeze a drop of liquid
1048708 hf goes down and
1048708 Viscosity goes up (curing)
1048708 Ft goes up (to separate)
When pullin apart
2008-spring-2004 SKim
11
DFA for bonding
1048708 Weak to tensile loading strong to shear and compressive1048708 Organic1048708 Epoxy acrylic etc1048708 Inorganic1048708 solder cement etc
2008-spring-2004 SKim
12
Solid-Liquid Brazing and Soldering
1048708 In brazing the filler material (silver brass bronze) has a melting point above 425 ordmC and in soldering the filler material (lead tin) has a melting point well below 425 ordmC1048708 Capillary forces for the wetting and flow of the liquid metal into the gaps1048708 Proper fluxes for lowering surface tension remove oxides and prevent oxidation
2008-spring-2004 SKim B Benhabib
13
Wave soldering
1048708 Exposed metal joints are passed over a wave in a continuous motion where liquid solder penetrates into the joint by capillary forces
2008-spring-2004 SKim B Benhabib
Enlarged area
Circuitboard
Solderfountain
Moltensolder
Heater Pump
Enlarged area
14
Welding
1048708 Solid-state welding
10487081048708 No liquid electrical chemical mechanical
1048708 Resistance diffusion ultrasonic
10487081048708 Fusion welding
10487081048708 Chemical Oxyfuel
10487081048708 Electrical Arc welding
1048708 1048708 Consumable electrode
10487081048708 Non-consumable electrode
2008-spring-2004 SKim
15
Fusion Welding
1048708 Heat source chemical electrical1048708 Heat intensity1048708 Control1048708 Incomplete fusion penetration1048708 Underfilling undercutting cracks1048708 Heat affected zone (HAZ)1048708 Feed rate
2008-spring-2004 SKim
16
Underfill and undercut
2008-spring-2004 SKim
underfill
undercut
Good weld
17
Heat Intensity
1048708 A measure of radiation intensity Wcm2
1048708 High intensity high heat flux the faster the melting1048708 Automation needed to prevent overmelting vaporizing1048708 For a planar heat source on steel tm= (5000HI)2
Oxy 20-30 sec E-beam μ sec
2008-spring-2004 SKim
AirFuelGas Flame
OxyacetyleneThermit
Friction
ArcWelding
Resistance Welding(Oxygen Cutting)
Electron BeamLaser Beam
18
Laser for Razor
- 500 μm spots- 3 million spots per hour
How fast the welding speed is required
Kalpakjian2008-spring-2004 SKim
19
Melting front speed2D simplification
The Jacob number
The thermal diffusivity is given by
The melt front moves as
2008-spring-2004 SKim
20
Welding speed
1048708 tm = (sm)2 (2 α Ja)1048708 Any longer over-melt
1048708 If the weld pool size is d in diameter then you must feed at a rate that exceeds dtmax1048708 HI increases welding speed must go up1048708 α Ja increases interaction time must go up
Weld pool size d
2008-spring-2004 SKim
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
2
Today
Ask ldquoDave and Patrdquo1048708 Joining amp Welding1048708 PP 771-861 Kalpakjian1048708 Quiz 1 on March 17th 1230 PM1048708 Closed book calculator1048708 Lecture notes HWs1048708 QampA session March 15th Monday 5-6PM 1048708 HW 4 due next Monday
2008-spring-2004 SKim
3
Joining
1048708 Cost1048708 Cheap but expensive labor
1048708 Quality1048708 Wide range
1048708 Flexibility1048708 Manual vs automated
1048708 Rate1048708 Slow in genera
Very Large Crude Carrier (VLCC)
2008-spring-2004 SKim
4
Joining processes
engine fasteners door
Mechanical nutsbolts
rivets c-clips pressure fits
Solid-liquid Adhesives
Soldering Brazing
Solid Friction Diffusion Explosion Ultrasound
Liquid
Chemical Oxyfuel Thermit
ECUS emission controller windshield plastic fans
Body muffler
Resistance Spot Seam Flash
door hingesConsumable electrode Shielded metal arc Submerged arc Gas metal arc
nonConsumable electrodeGas Tungsten Plasma Arc Electron Beam Laser welding
Arc Welding
2008-spring-2004 SKim
5
Mechanical Fastening
1048708 Any shape and material almost1048708 Disassemblable (except Rivets etc)1048708 Least expensive for low volume (standardized)1048708 Problems strength seal insertion loosening
Threaded Bolted Rivets Snap fit
Figures B Benhabib2008-spring-2004 SKim
6
Rivets
1048708 Cheap light weight donrsquot get loose1048708 Permanent less strong than bolts1048708 Rule of thumb1048708 Minimum spacing = 3 x d1048708 Maximum spacing = 16 x thickness of the outer plate
Rivets
2008-spring-2004 SKim
7
Mechanical fastening
1048708 Crimping1048708 Embossed protrusions1048708 Plastic deformation interference1048708 Appliance1048708 Automotive
Lego assembly elastic averaging
M Culpepper MIT2008-spring-2004 SKim
8
Mechanical Joining
1048708 Hemming seaming1048708 Bend edge of one component over another1048708 Automobile door stampings and trunk lids
2008-spring-2004 SKim
9
Adhesive Bonding
1048708 Quick and non-invasive1048708 Most materials with high surface to volume ratio1048708 Insulation (thermal electrical) conducting adhesives available1048708 Good damping1048708 Clean surface preparation1048708 Long curing hold time low service T1048708 Reliability quality1048708 Disassembly
2008-spring-2004 SKim
10
Stefan Equation
1048708 Squeeze a drop of liquid
1048708 hf goes down and
1048708 Viscosity goes up (curing)
1048708 Ft goes up (to separate)
When pullin apart
2008-spring-2004 SKim
11
DFA for bonding
1048708 Weak to tensile loading strong to shear and compressive1048708 Organic1048708 Epoxy acrylic etc1048708 Inorganic1048708 solder cement etc
2008-spring-2004 SKim
12
Solid-Liquid Brazing and Soldering
1048708 In brazing the filler material (silver brass bronze) has a melting point above 425 ordmC and in soldering the filler material (lead tin) has a melting point well below 425 ordmC1048708 Capillary forces for the wetting and flow of the liquid metal into the gaps1048708 Proper fluxes for lowering surface tension remove oxides and prevent oxidation
2008-spring-2004 SKim B Benhabib
13
Wave soldering
1048708 Exposed metal joints are passed over a wave in a continuous motion where liquid solder penetrates into the joint by capillary forces
2008-spring-2004 SKim B Benhabib
Enlarged area
Circuitboard
Solderfountain
Moltensolder
Heater Pump
Enlarged area
14
Welding
1048708 Solid-state welding
10487081048708 No liquid electrical chemical mechanical
1048708 Resistance diffusion ultrasonic
10487081048708 Fusion welding
10487081048708 Chemical Oxyfuel
10487081048708 Electrical Arc welding
1048708 1048708 Consumable electrode
10487081048708 Non-consumable electrode
2008-spring-2004 SKim
15
Fusion Welding
1048708 Heat source chemical electrical1048708 Heat intensity1048708 Control1048708 Incomplete fusion penetration1048708 Underfilling undercutting cracks1048708 Heat affected zone (HAZ)1048708 Feed rate
2008-spring-2004 SKim
16
Underfill and undercut
2008-spring-2004 SKim
underfill
undercut
Good weld
17
Heat Intensity
1048708 A measure of radiation intensity Wcm2
1048708 High intensity high heat flux the faster the melting1048708 Automation needed to prevent overmelting vaporizing1048708 For a planar heat source on steel tm= (5000HI)2
Oxy 20-30 sec E-beam μ sec
2008-spring-2004 SKim
AirFuelGas Flame
OxyacetyleneThermit
Friction
ArcWelding
Resistance Welding(Oxygen Cutting)
Electron BeamLaser Beam
18
Laser for Razor
- 500 μm spots- 3 million spots per hour
How fast the welding speed is required
Kalpakjian2008-spring-2004 SKim
19
Melting front speed2D simplification
The Jacob number
The thermal diffusivity is given by
The melt front moves as
2008-spring-2004 SKim
20
Welding speed
1048708 tm = (sm)2 (2 α Ja)1048708 Any longer over-melt
1048708 If the weld pool size is d in diameter then you must feed at a rate that exceeds dtmax1048708 HI increases welding speed must go up1048708 α Ja increases interaction time must go up
Weld pool size d
2008-spring-2004 SKim
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
3
Joining
1048708 Cost1048708 Cheap but expensive labor
1048708 Quality1048708 Wide range
1048708 Flexibility1048708 Manual vs automated
1048708 Rate1048708 Slow in genera
Very Large Crude Carrier (VLCC)
2008-spring-2004 SKim
4
Joining processes
engine fasteners door
Mechanical nutsbolts
rivets c-clips pressure fits
Solid-liquid Adhesives
Soldering Brazing
Solid Friction Diffusion Explosion Ultrasound
Liquid
Chemical Oxyfuel Thermit
ECUS emission controller windshield plastic fans
Body muffler
Resistance Spot Seam Flash
door hingesConsumable electrode Shielded metal arc Submerged arc Gas metal arc
nonConsumable electrodeGas Tungsten Plasma Arc Electron Beam Laser welding
Arc Welding
2008-spring-2004 SKim
5
Mechanical Fastening
1048708 Any shape and material almost1048708 Disassemblable (except Rivets etc)1048708 Least expensive for low volume (standardized)1048708 Problems strength seal insertion loosening
Threaded Bolted Rivets Snap fit
Figures B Benhabib2008-spring-2004 SKim
6
Rivets
1048708 Cheap light weight donrsquot get loose1048708 Permanent less strong than bolts1048708 Rule of thumb1048708 Minimum spacing = 3 x d1048708 Maximum spacing = 16 x thickness of the outer plate
Rivets
2008-spring-2004 SKim
7
Mechanical fastening
1048708 Crimping1048708 Embossed protrusions1048708 Plastic deformation interference1048708 Appliance1048708 Automotive
Lego assembly elastic averaging
M Culpepper MIT2008-spring-2004 SKim
8
Mechanical Joining
1048708 Hemming seaming1048708 Bend edge of one component over another1048708 Automobile door stampings and trunk lids
2008-spring-2004 SKim
9
Adhesive Bonding
1048708 Quick and non-invasive1048708 Most materials with high surface to volume ratio1048708 Insulation (thermal electrical) conducting adhesives available1048708 Good damping1048708 Clean surface preparation1048708 Long curing hold time low service T1048708 Reliability quality1048708 Disassembly
2008-spring-2004 SKim
10
Stefan Equation
1048708 Squeeze a drop of liquid
1048708 hf goes down and
1048708 Viscosity goes up (curing)
1048708 Ft goes up (to separate)
When pullin apart
2008-spring-2004 SKim
11
DFA for bonding
1048708 Weak to tensile loading strong to shear and compressive1048708 Organic1048708 Epoxy acrylic etc1048708 Inorganic1048708 solder cement etc
2008-spring-2004 SKim
12
Solid-Liquid Brazing and Soldering
1048708 In brazing the filler material (silver brass bronze) has a melting point above 425 ordmC and in soldering the filler material (lead tin) has a melting point well below 425 ordmC1048708 Capillary forces for the wetting and flow of the liquid metal into the gaps1048708 Proper fluxes for lowering surface tension remove oxides and prevent oxidation
2008-spring-2004 SKim B Benhabib
13
Wave soldering
1048708 Exposed metal joints are passed over a wave in a continuous motion where liquid solder penetrates into the joint by capillary forces
2008-spring-2004 SKim B Benhabib
Enlarged area
Circuitboard
Solderfountain
Moltensolder
Heater Pump
Enlarged area
14
Welding
1048708 Solid-state welding
10487081048708 No liquid electrical chemical mechanical
1048708 Resistance diffusion ultrasonic
10487081048708 Fusion welding
10487081048708 Chemical Oxyfuel
10487081048708 Electrical Arc welding
1048708 1048708 Consumable electrode
10487081048708 Non-consumable electrode
2008-spring-2004 SKim
15
Fusion Welding
1048708 Heat source chemical electrical1048708 Heat intensity1048708 Control1048708 Incomplete fusion penetration1048708 Underfilling undercutting cracks1048708 Heat affected zone (HAZ)1048708 Feed rate
2008-spring-2004 SKim
16
Underfill and undercut
2008-spring-2004 SKim
underfill
undercut
Good weld
17
Heat Intensity
1048708 A measure of radiation intensity Wcm2
1048708 High intensity high heat flux the faster the melting1048708 Automation needed to prevent overmelting vaporizing1048708 For a planar heat source on steel tm= (5000HI)2
Oxy 20-30 sec E-beam μ sec
2008-spring-2004 SKim
AirFuelGas Flame
OxyacetyleneThermit
Friction
ArcWelding
Resistance Welding(Oxygen Cutting)
Electron BeamLaser Beam
18
Laser for Razor
- 500 μm spots- 3 million spots per hour
How fast the welding speed is required
Kalpakjian2008-spring-2004 SKim
19
Melting front speed2D simplification
The Jacob number
The thermal diffusivity is given by
The melt front moves as
2008-spring-2004 SKim
20
Welding speed
1048708 tm = (sm)2 (2 α Ja)1048708 Any longer over-melt
1048708 If the weld pool size is d in diameter then you must feed at a rate that exceeds dtmax1048708 HI increases welding speed must go up1048708 α Ja increases interaction time must go up
Weld pool size d
2008-spring-2004 SKim
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
4
Joining processes
engine fasteners door
Mechanical nutsbolts
rivets c-clips pressure fits
Solid-liquid Adhesives
Soldering Brazing
Solid Friction Diffusion Explosion Ultrasound
Liquid
Chemical Oxyfuel Thermit
ECUS emission controller windshield plastic fans
Body muffler
Resistance Spot Seam Flash
door hingesConsumable electrode Shielded metal arc Submerged arc Gas metal arc
nonConsumable electrodeGas Tungsten Plasma Arc Electron Beam Laser welding
Arc Welding
2008-spring-2004 SKim
5
Mechanical Fastening
1048708 Any shape and material almost1048708 Disassemblable (except Rivets etc)1048708 Least expensive for low volume (standardized)1048708 Problems strength seal insertion loosening
Threaded Bolted Rivets Snap fit
Figures B Benhabib2008-spring-2004 SKim
6
Rivets
1048708 Cheap light weight donrsquot get loose1048708 Permanent less strong than bolts1048708 Rule of thumb1048708 Minimum spacing = 3 x d1048708 Maximum spacing = 16 x thickness of the outer plate
Rivets
2008-spring-2004 SKim
7
Mechanical fastening
1048708 Crimping1048708 Embossed protrusions1048708 Plastic deformation interference1048708 Appliance1048708 Automotive
Lego assembly elastic averaging
M Culpepper MIT2008-spring-2004 SKim
8
Mechanical Joining
1048708 Hemming seaming1048708 Bend edge of one component over another1048708 Automobile door stampings and trunk lids
2008-spring-2004 SKim
9
Adhesive Bonding
1048708 Quick and non-invasive1048708 Most materials with high surface to volume ratio1048708 Insulation (thermal electrical) conducting adhesives available1048708 Good damping1048708 Clean surface preparation1048708 Long curing hold time low service T1048708 Reliability quality1048708 Disassembly
2008-spring-2004 SKim
10
Stefan Equation
1048708 Squeeze a drop of liquid
1048708 hf goes down and
1048708 Viscosity goes up (curing)
1048708 Ft goes up (to separate)
When pullin apart
2008-spring-2004 SKim
11
DFA for bonding
1048708 Weak to tensile loading strong to shear and compressive1048708 Organic1048708 Epoxy acrylic etc1048708 Inorganic1048708 solder cement etc
2008-spring-2004 SKim
12
Solid-Liquid Brazing and Soldering
1048708 In brazing the filler material (silver brass bronze) has a melting point above 425 ordmC and in soldering the filler material (lead tin) has a melting point well below 425 ordmC1048708 Capillary forces for the wetting and flow of the liquid metal into the gaps1048708 Proper fluxes for lowering surface tension remove oxides and prevent oxidation
2008-spring-2004 SKim B Benhabib
13
Wave soldering
1048708 Exposed metal joints are passed over a wave in a continuous motion where liquid solder penetrates into the joint by capillary forces
2008-spring-2004 SKim B Benhabib
Enlarged area
Circuitboard
Solderfountain
Moltensolder
Heater Pump
Enlarged area
14
Welding
1048708 Solid-state welding
10487081048708 No liquid electrical chemical mechanical
1048708 Resistance diffusion ultrasonic
10487081048708 Fusion welding
10487081048708 Chemical Oxyfuel
10487081048708 Electrical Arc welding
1048708 1048708 Consumable electrode
10487081048708 Non-consumable electrode
2008-spring-2004 SKim
15
Fusion Welding
1048708 Heat source chemical electrical1048708 Heat intensity1048708 Control1048708 Incomplete fusion penetration1048708 Underfilling undercutting cracks1048708 Heat affected zone (HAZ)1048708 Feed rate
2008-spring-2004 SKim
16
Underfill and undercut
2008-spring-2004 SKim
underfill
undercut
Good weld
17
Heat Intensity
1048708 A measure of radiation intensity Wcm2
1048708 High intensity high heat flux the faster the melting1048708 Automation needed to prevent overmelting vaporizing1048708 For a planar heat source on steel tm= (5000HI)2
Oxy 20-30 sec E-beam μ sec
2008-spring-2004 SKim
AirFuelGas Flame
OxyacetyleneThermit
Friction
ArcWelding
Resistance Welding(Oxygen Cutting)
Electron BeamLaser Beam
18
Laser for Razor
- 500 μm spots- 3 million spots per hour
How fast the welding speed is required
Kalpakjian2008-spring-2004 SKim
19
Melting front speed2D simplification
The Jacob number
The thermal diffusivity is given by
The melt front moves as
2008-spring-2004 SKim
20
Welding speed
1048708 tm = (sm)2 (2 α Ja)1048708 Any longer over-melt
1048708 If the weld pool size is d in diameter then you must feed at a rate that exceeds dtmax1048708 HI increases welding speed must go up1048708 α Ja increases interaction time must go up
Weld pool size d
2008-spring-2004 SKim
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
5
Mechanical Fastening
1048708 Any shape and material almost1048708 Disassemblable (except Rivets etc)1048708 Least expensive for low volume (standardized)1048708 Problems strength seal insertion loosening
Threaded Bolted Rivets Snap fit
Figures B Benhabib2008-spring-2004 SKim
6
Rivets
1048708 Cheap light weight donrsquot get loose1048708 Permanent less strong than bolts1048708 Rule of thumb1048708 Minimum spacing = 3 x d1048708 Maximum spacing = 16 x thickness of the outer plate
Rivets
2008-spring-2004 SKim
7
Mechanical fastening
1048708 Crimping1048708 Embossed protrusions1048708 Plastic deformation interference1048708 Appliance1048708 Automotive
Lego assembly elastic averaging
M Culpepper MIT2008-spring-2004 SKim
8
Mechanical Joining
1048708 Hemming seaming1048708 Bend edge of one component over another1048708 Automobile door stampings and trunk lids
2008-spring-2004 SKim
9
Adhesive Bonding
1048708 Quick and non-invasive1048708 Most materials with high surface to volume ratio1048708 Insulation (thermal electrical) conducting adhesives available1048708 Good damping1048708 Clean surface preparation1048708 Long curing hold time low service T1048708 Reliability quality1048708 Disassembly
2008-spring-2004 SKim
10
Stefan Equation
1048708 Squeeze a drop of liquid
1048708 hf goes down and
1048708 Viscosity goes up (curing)
1048708 Ft goes up (to separate)
When pullin apart
2008-spring-2004 SKim
11
DFA for bonding
1048708 Weak to tensile loading strong to shear and compressive1048708 Organic1048708 Epoxy acrylic etc1048708 Inorganic1048708 solder cement etc
2008-spring-2004 SKim
12
Solid-Liquid Brazing and Soldering
1048708 In brazing the filler material (silver brass bronze) has a melting point above 425 ordmC and in soldering the filler material (lead tin) has a melting point well below 425 ordmC1048708 Capillary forces for the wetting and flow of the liquid metal into the gaps1048708 Proper fluxes for lowering surface tension remove oxides and prevent oxidation
2008-spring-2004 SKim B Benhabib
13
Wave soldering
1048708 Exposed metal joints are passed over a wave in a continuous motion where liquid solder penetrates into the joint by capillary forces
2008-spring-2004 SKim B Benhabib
Enlarged area
Circuitboard
Solderfountain
Moltensolder
Heater Pump
Enlarged area
14
Welding
1048708 Solid-state welding
10487081048708 No liquid electrical chemical mechanical
1048708 Resistance diffusion ultrasonic
10487081048708 Fusion welding
10487081048708 Chemical Oxyfuel
10487081048708 Electrical Arc welding
1048708 1048708 Consumable electrode
10487081048708 Non-consumable electrode
2008-spring-2004 SKim
15
Fusion Welding
1048708 Heat source chemical electrical1048708 Heat intensity1048708 Control1048708 Incomplete fusion penetration1048708 Underfilling undercutting cracks1048708 Heat affected zone (HAZ)1048708 Feed rate
2008-spring-2004 SKim
16
Underfill and undercut
2008-spring-2004 SKim
underfill
undercut
Good weld
17
Heat Intensity
1048708 A measure of radiation intensity Wcm2
1048708 High intensity high heat flux the faster the melting1048708 Automation needed to prevent overmelting vaporizing1048708 For a planar heat source on steel tm= (5000HI)2
Oxy 20-30 sec E-beam μ sec
2008-spring-2004 SKim
AirFuelGas Flame
OxyacetyleneThermit
Friction
ArcWelding
Resistance Welding(Oxygen Cutting)
Electron BeamLaser Beam
18
Laser for Razor
- 500 μm spots- 3 million spots per hour
How fast the welding speed is required
Kalpakjian2008-spring-2004 SKim
19
Melting front speed2D simplification
The Jacob number
The thermal diffusivity is given by
The melt front moves as
2008-spring-2004 SKim
20
Welding speed
1048708 tm = (sm)2 (2 α Ja)1048708 Any longer over-melt
1048708 If the weld pool size is d in diameter then you must feed at a rate that exceeds dtmax1048708 HI increases welding speed must go up1048708 α Ja increases interaction time must go up
Weld pool size d
2008-spring-2004 SKim
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
6
Rivets
1048708 Cheap light weight donrsquot get loose1048708 Permanent less strong than bolts1048708 Rule of thumb1048708 Minimum spacing = 3 x d1048708 Maximum spacing = 16 x thickness of the outer plate
Rivets
2008-spring-2004 SKim
7
Mechanical fastening
1048708 Crimping1048708 Embossed protrusions1048708 Plastic deformation interference1048708 Appliance1048708 Automotive
Lego assembly elastic averaging
M Culpepper MIT2008-spring-2004 SKim
8
Mechanical Joining
1048708 Hemming seaming1048708 Bend edge of one component over another1048708 Automobile door stampings and trunk lids
2008-spring-2004 SKim
9
Adhesive Bonding
1048708 Quick and non-invasive1048708 Most materials with high surface to volume ratio1048708 Insulation (thermal electrical) conducting adhesives available1048708 Good damping1048708 Clean surface preparation1048708 Long curing hold time low service T1048708 Reliability quality1048708 Disassembly
2008-spring-2004 SKim
10
Stefan Equation
1048708 Squeeze a drop of liquid
1048708 hf goes down and
1048708 Viscosity goes up (curing)
1048708 Ft goes up (to separate)
When pullin apart
2008-spring-2004 SKim
11
DFA for bonding
1048708 Weak to tensile loading strong to shear and compressive1048708 Organic1048708 Epoxy acrylic etc1048708 Inorganic1048708 solder cement etc
2008-spring-2004 SKim
12
Solid-Liquid Brazing and Soldering
1048708 In brazing the filler material (silver brass bronze) has a melting point above 425 ordmC and in soldering the filler material (lead tin) has a melting point well below 425 ordmC1048708 Capillary forces for the wetting and flow of the liquid metal into the gaps1048708 Proper fluxes for lowering surface tension remove oxides and prevent oxidation
2008-spring-2004 SKim B Benhabib
13
Wave soldering
1048708 Exposed metal joints are passed over a wave in a continuous motion where liquid solder penetrates into the joint by capillary forces
2008-spring-2004 SKim B Benhabib
Enlarged area
Circuitboard
Solderfountain
Moltensolder
Heater Pump
Enlarged area
14
Welding
1048708 Solid-state welding
10487081048708 No liquid electrical chemical mechanical
1048708 Resistance diffusion ultrasonic
10487081048708 Fusion welding
10487081048708 Chemical Oxyfuel
10487081048708 Electrical Arc welding
1048708 1048708 Consumable electrode
10487081048708 Non-consumable electrode
2008-spring-2004 SKim
15
Fusion Welding
1048708 Heat source chemical electrical1048708 Heat intensity1048708 Control1048708 Incomplete fusion penetration1048708 Underfilling undercutting cracks1048708 Heat affected zone (HAZ)1048708 Feed rate
2008-spring-2004 SKim
16
Underfill and undercut
2008-spring-2004 SKim
underfill
undercut
Good weld
17
Heat Intensity
1048708 A measure of radiation intensity Wcm2
1048708 High intensity high heat flux the faster the melting1048708 Automation needed to prevent overmelting vaporizing1048708 For a planar heat source on steel tm= (5000HI)2
Oxy 20-30 sec E-beam μ sec
2008-spring-2004 SKim
AirFuelGas Flame
OxyacetyleneThermit
Friction
ArcWelding
Resistance Welding(Oxygen Cutting)
Electron BeamLaser Beam
18
Laser for Razor
- 500 μm spots- 3 million spots per hour
How fast the welding speed is required
Kalpakjian2008-spring-2004 SKim
19
Melting front speed2D simplification
The Jacob number
The thermal diffusivity is given by
The melt front moves as
2008-spring-2004 SKim
20
Welding speed
1048708 tm = (sm)2 (2 α Ja)1048708 Any longer over-melt
1048708 If the weld pool size is d in diameter then you must feed at a rate that exceeds dtmax1048708 HI increases welding speed must go up1048708 α Ja increases interaction time must go up
Weld pool size d
2008-spring-2004 SKim
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
7
Mechanical fastening
1048708 Crimping1048708 Embossed protrusions1048708 Plastic deformation interference1048708 Appliance1048708 Automotive
Lego assembly elastic averaging
M Culpepper MIT2008-spring-2004 SKim
8
Mechanical Joining
1048708 Hemming seaming1048708 Bend edge of one component over another1048708 Automobile door stampings and trunk lids
2008-spring-2004 SKim
9
Adhesive Bonding
1048708 Quick and non-invasive1048708 Most materials with high surface to volume ratio1048708 Insulation (thermal electrical) conducting adhesives available1048708 Good damping1048708 Clean surface preparation1048708 Long curing hold time low service T1048708 Reliability quality1048708 Disassembly
2008-spring-2004 SKim
10
Stefan Equation
1048708 Squeeze a drop of liquid
1048708 hf goes down and
1048708 Viscosity goes up (curing)
1048708 Ft goes up (to separate)
When pullin apart
2008-spring-2004 SKim
11
DFA for bonding
1048708 Weak to tensile loading strong to shear and compressive1048708 Organic1048708 Epoxy acrylic etc1048708 Inorganic1048708 solder cement etc
2008-spring-2004 SKim
12
Solid-Liquid Brazing and Soldering
1048708 In brazing the filler material (silver brass bronze) has a melting point above 425 ordmC and in soldering the filler material (lead tin) has a melting point well below 425 ordmC1048708 Capillary forces for the wetting and flow of the liquid metal into the gaps1048708 Proper fluxes for lowering surface tension remove oxides and prevent oxidation
2008-spring-2004 SKim B Benhabib
13
Wave soldering
1048708 Exposed metal joints are passed over a wave in a continuous motion where liquid solder penetrates into the joint by capillary forces
2008-spring-2004 SKim B Benhabib
Enlarged area
Circuitboard
Solderfountain
Moltensolder
Heater Pump
Enlarged area
14
Welding
1048708 Solid-state welding
10487081048708 No liquid electrical chemical mechanical
1048708 Resistance diffusion ultrasonic
10487081048708 Fusion welding
10487081048708 Chemical Oxyfuel
10487081048708 Electrical Arc welding
1048708 1048708 Consumable electrode
10487081048708 Non-consumable electrode
2008-spring-2004 SKim
15
Fusion Welding
1048708 Heat source chemical electrical1048708 Heat intensity1048708 Control1048708 Incomplete fusion penetration1048708 Underfilling undercutting cracks1048708 Heat affected zone (HAZ)1048708 Feed rate
2008-spring-2004 SKim
16
Underfill and undercut
2008-spring-2004 SKim
underfill
undercut
Good weld
17
Heat Intensity
1048708 A measure of radiation intensity Wcm2
1048708 High intensity high heat flux the faster the melting1048708 Automation needed to prevent overmelting vaporizing1048708 For a planar heat source on steel tm= (5000HI)2
Oxy 20-30 sec E-beam μ sec
2008-spring-2004 SKim
AirFuelGas Flame
OxyacetyleneThermit
Friction
ArcWelding
Resistance Welding(Oxygen Cutting)
Electron BeamLaser Beam
18
Laser for Razor
- 500 μm spots- 3 million spots per hour
How fast the welding speed is required
Kalpakjian2008-spring-2004 SKim
19
Melting front speed2D simplification
The Jacob number
The thermal diffusivity is given by
The melt front moves as
2008-spring-2004 SKim
20
Welding speed
1048708 tm = (sm)2 (2 α Ja)1048708 Any longer over-melt
1048708 If the weld pool size is d in diameter then you must feed at a rate that exceeds dtmax1048708 HI increases welding speed must go up1048708 α Ja increases interaction time must go up
Weld pool size d
2008-spring-2004 SKim
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
8
Mechanical Joining
1048708 Hemming seaming1048708 Bend edge of one component over another1048708 Automobile door stampings and trunk lids
2008-spring-2004 SKim
9
Adhesive Bonding
1048708 Quick and non-invasive1048708 Most materials with high surface to volume ratio1048708 Insulation (thermal electrical) conducting adhesives available1048708 Good damping1048708 Clean surface preparation1048708 Long curing hold time low service T1048708 Reliability quality1048708 Disassembly
2008-spring-2004 SKim
10
Stefan Equation
1048708 Squeeze a drop of liquid
1048708 hf goes down and
1048708 Viscosity goes up (curing)
1048708 Ft goes up (to separate)
When pullin apart
2008-spring-2004 SKim
11
DFA for bonding
1048708 Weak to tensile loading strong to shear and compressive1048708 Organic1048708 Epoxy acrylic etc1048708 Inorganic1048708 solder cement etc
2008-spring-2004 SKim
12
Solid-Liquid Brazing and Soldering
1048708 In brazing the filler material (silver brass bronze) has a melting point above 425 ordmC and in soldering the filler material (lead tin) has a melting point well below 425 ordmC1048708 Capillary forces for the wetting and flow of the liquid metal into the gaps1048708 Proper fluxes for lowering surface tension remove oxides and prevent oxidation
2008-spring-2004 SKim B Benhabib
13
Wave soldering
1048708 Exposed metal joints are passed over a wave in a continuous motion where liquid solder penetrates into the joint by capillary forces
2008-spring-2004 SKim B Benhabib
Enlarged area
Circuitboard
Solderfountain
Moltensolder
Heater Pump
Enlarged area
14
Welding
1048708 Solid-state welding
10487081048708 No liquid electrical chemical mechanical
1048708 Resistance diffusion ultrasonic
10487081048708 Fusion welding
10487081048708 Chemical Oxyfuel
10487081048708 Electrical Arc welding
1048708 1048708 Consumable electrode
10487081048708 Non-consumable electrode
2008-spring-2004 SKim
15
Fusion Welding
1048708 Heat source chemical electrical1048708 Heat intensity1048708 Control1048708 Incomplete fusion penetration1048708 Underfilling undercutting cracks1048708 Heat affected zone (HAZ)1048708 Feed rate
2008-spring-2004 SKim
16
Underfill and undercut
2008-spring-2004 SKim
underfill
undercut
Good weld
17
Heat Intensity
1048708 A measure of radiation intensity Wcm2
1048708 High intensity high heat flux the faster the melting1048708 Automation needed to prevent overmelting vaporizing1048708 For a planar heat source on steel tm= (5000HI)2
Oxy 20-30 sec E-beam μ sec
2008-spring-2004 SKim
AirFuelGas Flame
OxyacetyleneThermit
Friction
ArcWelding
Resistance Welding(Oxygen Cutting)
Electron BeamLaser Beam
18
Laser for Razor
- 500 μm spots- 3 million spots per hour
How fast the welding speed is required
Kalpakjian2008-spring-2004 SKim
19
Melting front speed2D simplification
The Jacob number
The thermal diffusivity is given by
The melt front moves as
2008-spring-2004 SKim
20
Welding speed
1048708 tm = (sm)2 (2 α Ja)1048708 Any longer over-melt
1048708 If the weld pool size is d in diameter then you must feed at a rate that exceeds dtmax1048708 HI increases welding speed must go up1048708 α Ja increases interaction time must go up
Weld pool size d
2008-spring-2004 SKim
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
9
Adhesive Bonding
1048708 Quick and non-invasive1048708 Most materials with high surface to volume ratio1048708 Insulation (thermal electrical) conducting adhesives available1048708 Good damping1048708 Clean surface preparation1048708 Long curing hold time low service T1048708 Reliability quality1048708 Disassembly
2008-spring-2004 SKim
10
Stefan Equation
1048708 Squeeze a drop of liquid
1048708 hf goes down and
1048708 Viscosity goes up (curing)
1048708 Ft goes up (to separate)
When pullin apart
2008-spring-2004 SKim
11
DFA for bonding
1048708 Weak to tensile loading strong to shear and compressive1048708 Organic1048708 Epoxy acrylic etc1048708 Inorganic1048708 solder cement etc
2008-spring-2004 SKim
12
Solid-Liquid Brazing and Soldering
1048708 In brazing the filler material (silver brass bronze) has a melting point above 425 ordmC and in soldering the filler material (lead tin) has a melting point well below 425 ordmC1048708 Capillary forces for the wetting and flow of the liquid metal into the gaps1048708 Proper fluxes for lowering surface tension remove oxides and prevent oxidation
2008-spring-2004 SKim B Benhabib
13
Wave soldering
1048708 Exposed metal joints are passed over a wave in a continuous motion where liquid solder penetrates into the joint by capillary forces
2008-spring-2004 SKim B Benhabib
Enlarged area
Circuitboard
Solderfountain
Moltensolder
Heater Pump
Enlarged area
14
Welding
1048708 Solid-state welding
10487081048708 No liquid electrical chemical mechanical
1048708 Resistance diffusion ultrasonic
10487081048708 Fusion welding
10487081048708 Chemical Oxyfuel
10487081048708 Electrical Arc welding
1048708 1048708 Consumable electrode
10487081048708 Non-consumable electrode
2008-spring-2004 SKim
15
Fusion Welding
1048708 Heat source chemical electrical1048708 Heat intensity1048708 Control1048708 Incomplete fusion penetration1048708 Underfilling undercutting cracks1048708 Heat affected zone (HAZ)1048708 Feed rate
2008-spring-2004 SKim
16
Underfill and undercut
2008-spring-2004 SKim
underfill
undercut
Good weld
17
Heat Intensity
1048708 A measure of radiation intensity Wcm2
1048708 High intensity high heat flux the faster the melting1048708 Automation needed to prevent overmelting vaporizing1048708 For a planar heat source on steel tm= (5000HI)2
Oxy 20-30 sec E-beam μ sec
2008-spring-2004 SKim
AirFuelGas Flame
OxyacetyleneThermit
Friction
ArcWelding
Resistance Welding(Oxygen Cutting)
Electron BeamLaser Beam
18
Laser for Razor
- 500 μm spots- 3 million spots per hour
How fast the welding speed is required
Kalpakjian2008-spring-2004 SKim
19
Melting front speed2D simplification
The Jacob number
The thermal diffusivity is given by
The melt front moves as
2008-spring-2004 SKim
20
Welding speed
1048708 tm = (sm)2 (2 α Ja)1048708 Any longer over-melt
1048708 If the weld pool size is d in diameter then you must feed at a rate that exceeds dtmax1048708 HI increases welding speed must go up1048708 α Ja increases interaction time must go up
Weld pool size d
2008-spring-2004 SKim
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
10
Stefan Equation
1048708 Squeeze a drop of liquid
1048708 hf goes down and
1048708 Viscosity goes up (curing)
1048708 Ft goes up (to separate)
When pullin apart
2008-spring-2004 SKim
11
DFA for bonding
1048708 Weak to tensile loading strong to shear and compressive1048708 Organic1048708 Epoxy acrylic etc1048708 Inorganic1048708 solder cement etc
2008-spring-2004 SKim
12
Solid-Liquid Brazing and Soldering
1048708 In brazing the filler material (silver brass bronze) has a melting point above 425 ordmC and in soldering the filler material (lead tin) has a melting point well below 425 ordmC1048708 Capillary forces for the wetting and flow of the liquid metal into the gaps1048708 Proper fluxes for lowering surface tension remove oxides and prevent oxidation
2008-spring-2004 SKim B Benhabib
13
Wave soldering
1048708 Exposed metal joints are passed over a wave in a continuous motion where liquid solder penetrates into the joint by capillary forces
2008-spring-2004 SKim B Benhabib
Enlarged area
Circuitboard
Solderfountain
Moltensolder
Heater Pump
Enlarged area
14
Welding
1048708 Solid-state welding
10487081048708 No liquid electrical chemical mechanical
1048708 Resistance diffusion ultrasonic
10487081048708 Fusion welding
10487081048708 Chemical Oxyfuel
10487081048708 Electrical Arc welding
1048708 1048708 Consumable electrode
10487081048708 Non-consumable electrode
2008-spring-2004 SKim
15
Fusion Welding
1048708 Heat source chemical electrical1048708 Heat intensity1048708 Control1048708 Incomplete fusion penetration1048708 Underfilling undercutting cracks1048708 Heat affected zone (HAZ)1048708 Feed rate
2008-spring-2004 SKim
16
Underfill and undercut
2008-spring-2004 SKim
underfill
undercut
Good weld
17
Heat Intensity
1048708 A measure of radiation intensity Wcm2
1048708 High intensity high heat flux the faster the melting1048708 Automation needed to prevent overmelting vaporizing1048708 For a planar heat source on steel tm= (5000HI)2
Oxy 20-30 sec E-beam μ sec
2008-spring-2004 SKim
AirFuelGas Flame
OxyacetyleneThermit
Friction
ArcWelding
Resistance Welding(Oxygen Cutting)
Electron BeamLaser Beam
18
Laser for Razor
- 500 μm spots- 3 million spots per hour
How fast the welding speed is required
Kalpakjian2008-spring-2004 SKim
19
Melting front speed2D simplification
The Jacob number
The thermal diffusivity is given by
The melt front moves as
2008-spring-2004 SKim
20
Welding speed
1048708 tm = (sm)2 (2 α Ja)1048708 Any longer over-melt
1048708 If the weld pool size is d in diameter then you must feed at a rate that exceeds dtmax1048708 HI increases welding speed must go up1048708 α Ja increases interaction time must go up
Weld pool size d
2008-spring-2004 SKim
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
11
DFA for bonding
1048708 Weak to tensile loading strong to shear and compressive1048708 Organic1048708 Epoxy acrylic etc1048708 Inorganic1048708 solder cement etc
2008-spring-2004 SKim
12
Solid-Liquid Brazing and Soldering
1048708 In brazing the filler material (silver brass bronze) has a melting point above 425 ordmC and in soldering the filler material (lead tin) has a melting point well below 425 ordmC1048708 Capillary forces for the wetting and flow of the liquid metal into the gaps1048708 Proper fluxes for lowering surface tension remove oxides and prevent oxidation
2008-spring-2004 SKim B Benhabib
13
Wave soldering
1048708 Exposed metal joints are passed over a wave in a continuous motion where liquid solder penetrates into the joint by capillary forces
2008-spring-2004 SKim B Benhabib
Enlarged area
Circuitboard
Solderfountain
Moltensolder
Heater Pump
Enlarged area
14
Welding
1048708 Solid-state welding
10487081048708 No liquid electrical chemical mechanical
1048708 Resistance diffusion ultrasonic
10487081048708 Fusion welding
10487081048708 Chemical Oxyfuel
10487081048708 Electrical Arc welding
1048708 1048708 Consumable electrode
10487081048708 Non-consumable electrode
2008-spring-2004 SKim
15
Fusion Welding
1048708 Heat source chemical electrical1048708 Heat intensity1048708 Control1048708 Incomplete fusion penetration1048708 Underfilling undercutting cracks1048708 Heat affected zone (HAZ)1048708 Feed rate
2008-spring-2004 SKim
16
Underfill and undercut
2008-spring-2004 SKim
underfill
undercut
Good weld
17
Heat Intensity
1048708 A measure of radiation intensity Wcm2
1048708 High intensity high heat flux the faster the melting1048708 Automation needed to prevent overmelting vaporizing1048708 For a planar heat source on steel tm= (5000HI)2
Oxy 20-30 sec E-beam μ sec
2008-spring-2004 SKim
AirFuelGas Flame
OxyacetyleneThermit
Friction
ArcWelding
Resistance Welding(Oxygen Cutting)
Electron BeamLaser Beam
18
Laser for Razor
- 500 μm spots- 3 million spots per hour
How fast the welding speed is required
Kalpakjian2008-spring-2004 SKim
19
Melting front speed2D simplification
The Jacob number
The thermal diffusivity is given by
The melt front moves as
2008-spring-2004 SKim
20
Welding speed
1048708 tm = (sm)2 (2 α Ja)1048708 Any longer over-melt
1048708 If the weld pool size is d in diameter then you must feed at a rate that exceeds dtmax1048708 HI increases welding speed must go up1048708 α Ja increases interaction time must go up
Weld pool size d
2008-spring-2004 SKim
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
12
Solid-Liquid Brazing and Soldering
1048708 In brazing the filler material (silver brass bronze) has a melting point above 425 ordmC and in soldering the filler material (lead tin) has a melting point well below 425 ordmC1048708 Capillary forces for the wetting and flow of the liquid metal into the gaps1048708 Proper fluxes for lowering surface tension remove oxides and prevent oxidation
2008-spring-2004 SKim B Benhabib
13
Wave soldering
1048708 Exposed metal joints are passed over a wave in a continuous motion where liquid solder penetrates into the joint by capillary forces
2008-spring-2004 SKim B Benhabib
Enlarged area
Circuitboard
Solderfountain
Moltensolder
Heater Pump
Enlarged area
14
Welding
1048708 Solid-state welding
10487081048708 No liquid electrical chemical mechanical
1048708 Resistance diffusion ultrasonic
10487081048708 Fusion welding
10487081048708 Chemical Oxyfuel
10487081048708 Electrical Arc welding
1048708 1048708 Consumable electrode
10487081048708 Non-consumable electrode
2008-spring-2004 SKim
15
Fusion Welding
1048708 Heat source chemical electrical1048708 Heat intensity1048708 Control1048708 Incomplete fusion penetration1048708 Underfilling undercutting cracks1048708 Heat affected zone (HAZ)1048708 Feed rate
2008-spring-2004 SKim
16
Underfill and undercut
2008-spring-2004 SKim
underfill
undercut
Good weld
17
Heat Intensity
1048708 A measure of radiation intensity Wcm2
1048708 High intensity high heat flux the faster the melting1048708 Automation needed to prevent overmelting vaporizing1048708 For a planar heat source on steel tm= (5000HI)2
Oxy 20-30 sec E-beam μ sec
2008-spring-2004 SKim
AirFuelGas Flame
OxyacetyleneThermit
Friction
ArcWelding
Resistance Welding(Oxygen Cutting)
Electron BeamLaser Beam
18
Laser for Razor
- 500 μm spots- 3 million spots per hour
How fast the welding speed is required
Kalpakjian2008-spring-2004 SKim
19
Melting front speed2D simplification
The Jacob number
The thermal diffusivity is given by
The melt front moves as
2008-spring-2004 SKim
20
Welding speed
1048708 tm = (sm)2 (2 α Ja)1048708 Any longer over-melt
1048708 If the weld pool size is d in diameter then you must feed at a rate that exceeds dtmax1048708 HI increases welding speed must go up1048708 α Ja increases interaction time must go up
Weld pool size d
2008-spring-2004 SKim
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
13
Wave soldering
1048708 Exposed metal joints are passed over a wave in a continuous motion where liquid solder penetrates into the joint by capillary forces
2008-spring-2004 SKim B Benhabib
Enlarged area
Circuitboard
Solderfountain
Moltensolder
Heater Pump
Enlarged area
14
Welding
1048708 Solid-state welding
10487081048708 No liquid electrical chemical mechanical
1048708 Resistance diffusion ultrasonic
10487081048708 Fusion welding
10487081048708 Chemical Oxyfuel
10487081048708 Electrical Arc welding
1048708 1048708 Consumable electrode
10487081048708 Non-consumable electrode
2008-spring-2004 SKim
15
Fusion Welding
1048708 Heat source chemical electrical1048708 Heat intensity1048708 Control1048708 Incomplete fusion penetration1048708 Underfilling undercutting cracks1048708 Heat affected zone (HAZ)1048708 Feed rate
2008-spring-2004 SKim
16
Underfill and undercut
2008-spring-2004 SKim
underfill
undercut
Good weld
17
Heat Intensity
1048708 A measure of radiation intensity Wcm2
1048708 High intensity high heat flux the faster the melting1048708 Automation needed to prevent overmelting vaporizing1048708 For a planar heat source on steel tm= (5000HI)2
Oxy 20-30 sec E-beam μ sec
2008-spring-2004 SKim
AirFuelGas Flame
OxyacetyleneThermit
Friction
ArcWelding
Resistance Welding(Oxygen Cutting)
Electron BeamLaser Beam
18
Laser for Razor
- 500 μm spots- 3 million spots per hour
How fast the welding speed is required
Kalpakjian2008-spring-2004 SKim
19
Melting front speed2D simplification
The Jacob number
The thermal diffusivity is given by
The melt front moves as
2008-spring-2004 SKim
20
Welding speed
1048708 tm = (sm)2 (2 α Ja)1048708 Any longer over-melt
1048708 If the weld pool size is d in diameter then you must feed at a rate that exceeds dtmax1048708 HI increases welding speed must go up1048708 α Ja increases interaction time must go up
Weld pool size d
2008-spring-2004 SKim
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
14
Welding
1048708 Solid-state welding
10487081048708 No liquid electrical chemical mechanical
1048708 Resistance diffusion ultrasonic
10487081048708 Fusion welding
10487081048708 Chemical Oxyfuel
10487081048708 Electrical Arc welding
1048708 1048708 Consumable electrode
10487081048708 Non-consumable electrode
2008-spring-2004 SKim
15
Fusion Welding
1048708 Heat source chemical electrical1048708 Heat intensity1048708 Control1048708 Incomplete fusion penetration1048708 Underfilling undercutting cracks1048708 Heat affected zone (HAZ)1048708 Feed rate
2008-spring-2004 SKim
16
Underfill and undercut
2008-spring-2004 SKim
underfill
undercut
Good weld
17
Heat Intensity
1048708 A measure of radiation intensity Wcm2
1048708 High intensity high heat flux the faster the melting1048708 Automation needed to prevent overmelting vaporizing1048708 For a planar heat source on steel tm= (5000HI)2
Oxy 20-30 sec E-beam μ sec
2008-spring-2004 SKim
AirFuelGas Flame
OxyacetyleneThermit
Friction
ArcWelding
Resistance Welding(Oxygen Cutting)
Electron BeamLaser Beam
18
Laser for Razor
- 500 μm spots- 3 million spots per hour
How fast the welding speed is required
Kalpakjian2008-spring-2004 SKim
19
Melting front speed2D simplification
The Jacob number
The thermal diffusivity is given by
The melt front moves as
2008-spring-2004 SKim
20
Welding speed
1048708 tm = (sm)2 (2 α Ja)1048708 Any longer over-melt
1048708 If the weld pool size is d in diameter then you must feed at a rate that exceeds dtmax1048708 HI increases welding speed must go up1048708 α Ja increases interaction time must go up
Weld pool size d
2008-spring-2004 SKim
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
15
Fusion Welding
1048708 Heat source chemical electrical1048708 Heat intensity1048708 Control1048708 Incomplete fusion penetration1048708 Underfilling undercutting cracks1048708 Heat affected zone (HAZ)1048708 Feed rate
2008-spring-2004 SKim
16
Underfill and undercut
2008-spring-2004 SKim
underfill
undercut
Good weld
17
Heat Intensity
1048708 A measure of radiation intensity Wcm2
1048708 High intensity high heat flux the faster the melting1048708 Automation needed to prevent overmelting vaporizing1048708 For a planar heat source on steel tm= (5000HI)2
Oxy 20-30 sec E-beam μ sec
2008-spring-2004 SKim
AirFuelGas Flame
OxyacetyleneThermit
Friction
ArcWelding
Resistance Welding(Oxygen Cutting)
Electron BeamLaser Beam
18
Laser for Razor
- 500 μm spots- 3 million spots per hour
How fast the welding speed is required
Kalpakjian2008-spring-2004 SKim
19
Melting front speed2D simplification
The Jacob number
The thermal diffusivity is given by
The melt front moves as
2008-spring-2004 SKim
20
Welding speed
1048708 tm = (sm)2 (2 α Ja)1048708 Any longer over-melt
1048708 If the weld pool size is d in diameter then you must feed at a rate that exceeds dtmax1048708 HI increases welding speed must go up1048708 α Ja increases interaction time must go up
Weld pool size d
2008-spring-2004 SKim
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
16
Underfill and undercut
2008-spring-2004 SKim
underfill
undercut
Good weld
17
Heat Intensity
1048708 A measure of radiation intensity Wcm2
1048708 High intensity high heat flux the faster the melting1048708 Automation needed to prevent overmelting vaporizing1048708 For a planar heat source on steel tm= (5000HI)2
Oxy 20-30 sec E-beam μ sec
2008-spring-2004 SKim
AirFuelGas Flame
OxyacetyleneThermit
Friction
ArcWelding
Resistance Welding(Oxygen Cutting)
Electron BeamLaser Beam
18
Laser for Razor
- 500 μm spots- 3 million spots per hour
How fast the welding speed is required
Kalpakjian2008-spring-2004 SKim
19
Melting front speed2D simplification
The Jacob number
The thermal diffusivity is given by
The melt front moves as
2008-spring-2004 SKim
20
Welding speed
1048708 tm = (sm)2 (2 α Ja)1048708 Any longer over-melt
1048708 If the weld pool size is d in diameter then you must feed at a rate that exceeds dtmax1048708 HI increases welding speed must go up1048708 α Ja increases interaction time must go up
Weld pool size d
2008-spring-2004 SKim
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
17
Heat Intensity
1048708 A measure of radiation intensity Wcm2
1048708 High intensity high heat flux the faster the melting1048708 Automation needed to prevent overmelting vaporizing1048708 For a planar heat source on steel tm= (5000HI)2
Oxy 20-30 sec E-beam μ sec
2008-spring-2004 SKim
AirFuelGas Flame
OxyacetyleneThermit
Friction
ArcWelding
Resistance Welding(Oxygen Cutting)
Electron BeamLaser Beam
18
Laser for Razor
- 500 μm spots- 3 million spots per hour
How fast the welding speed is required
Kalpakjian2008-spring-2004 SKim
19
Melting front speed2D simplification
The Jacob number
The thermal diffusivity is given by
The melt front moves as
2008-spring-2004 SKim
20
Welding speed
1048708 tm = (sm)2 (2 α Ja)1048708 Any longer over-melt
1048708 If the weld pool size is d in diameter then you must feed at a rate that exceeds dtmax1048708 HI increases welding speed must go up1048708 α Ja increases interaction time must go up
Weld pool size d
2008-spring-2004 SKim
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
18
Laser for Razor
- 500 μm spots- 3 million spots per hour
How fast the welding speed is required
Kalpakjian2008-spring-2004 SKim
19
Melting front speed2D simplification
The Jacob number
The thermal diffusivity is given by
The melt front moves as
2008-spring-2004 SKim
20
Welding speed
1048708 tm = (sm)2 (2 α Ja)1048708 Any longer over-melt
1048708 If the weld pool size is d in diameter then you must feed at a rate that exceeds dtmax1048708 HI increases welding speed must go up1048708 α Ja increases interaction time must go up
Weld pool size d
2008-spring-2004 SKim
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
19
Melting front speed2D simplification
The Jacob number
The thermal diffusivity is given by
The melt front moves as
2008-spring-2004 SKim
20
Welding speed
1048708 tm = (sm)2 (2 α Ja)1048708 Any longer over-melt
1048708 If the weld pool size is d in diameter then you must feed at a rate that exceeds dtmax1048708 HI increases welding speed must go up1048708 α Ja increases interaction time must go up
Weld pool size d
2008-spring-2004 SKim
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
20
Welding speed
1048708 tm = (sm)2 (2 α Ja)1048708 Any longer over-melt
1048708 If the weld pool size is d in diameter then you must feed at a rate that exceeds dtmax1048708 HI increases welding speed must go up1048708 α Ja increases interaction time must go up
Weld pool size d
2008-spring-2004 SKim
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
21
Weld Pool ndash Heat SourceInteraction Time
2008-spring-2004 SKim J Chun
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
22
HAZ(Heat Affected Zone)
1048708 Bad microstructure course grains weak to corrosion1048708 Plastic vs Metal
Temp
Base metal
HAZ
Weld metalMolten metal
Melting point
Microstructure change temperature
Base metal temperature
2008-spring-2004 SKim
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
23
Heat Affected Zone
1048708 Region near the weld pool is affected by heat Microstructure changes1048708 s ~ (α t)05
1048708 The size of the heat affected zone is controlled by the thermal diffusivity α Al Cu1048708 HI time (speed)1048708 Metal vs Plastic
2008-spring-2004 SKim
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
24
Heat Affected Zone (HAZ)
2008-spring-2004 SKim
Grain structureWeld lineIntergranular corrosionrecrystallization
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
25
Oxyfuel Gas Welding
1048708 Low cost manual1048708 Oxyfuel Oxygen + Fuel (Acetylene methyacetylene- propedieneetc) can reach 3300oC1048708 Stoichiometry neutral flame
1048708 More oxygen will cause oxidization (Oxidizing flame) bad for steels OK for copper1048708 More fuel will cause carburization (carburizing flame) Low heat for brazing soldering flame hardening
2008-spring-2004 SKim
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
26
Arc fusion welding
1048708 Temperature up to 30000oC1048708 Heat travels with the electrons1048708 Straight polarity workpiece + electrode ndash1048708 Shallow penetration sheet metal wide gaps1048708 reverse polarity1048708 Deeper penetration
Arrangement forconsumable electrodes
Heat generated at anode isabout 15 of the heatgenerated at cathode
Eelectron at cathode is given bythree components
Kinetic energyDrop across cool gas boundary
Work function(heat of condensation)
2008-spring-2004 SKim
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
27
Consumable electrode processes
1048708 Shielded metal arc welding1048708 Cheapest and most basic process lt $15001048708 50A-300A lt10KW1048708 Workpiece thickness 3-20mm
2008-spring-2004 SKim
SlagCoating deoxidizes weld and provides shielding gas
Multiple passSlag removal
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
28
Fusion Arc Welding
1048708 Preventing oxidation is the most important problem1048708 Coated electrodes to provide shielding gas1048708 Coatings fluorides silicate binders(clay) cellulose carbonates1048708 Electrodes different materials such as mild steel1048708 Submerged arc welding covered by granular flux1048708 Flat surfaces high throughput good quality1048708 Inert gas from external source1048708 Gas metal arc welding (MIG)1048708 Flux-cored arc welding etc (very versatile with proper fluxes)
2008-spring-2004 SKim
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
29
Gas Metal Arc Welding
Metal transfer- Spray transfer- Globular transfer- Short circuiting
Gas metal arc welding is aspecial variation on arc weldingin which the electrode fillermetal is fed directly through thetorch tip As arcing occurs theelectrode instantly meltsforming molten droplets that fallinto the weld pool Shielding gasis supplied through the torch tipto prevent chemical interactionswith the surroundingatmosphere
2008-spring-2004 SKim
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
30
Non-consumable electrode weldingGas Tungsten Arc Welding
1048708 Gas tungsten arc welding formerly known as TIG welding10487081048708 Tungsten electrode + filler wire10487081048708 Good for thin materials better control Al MgTi etc10487081048708 High quality and finish10487081048708 Tungsten electrode contamination10487081048708 200A DC-500A AC 8kW-50kW
2008-spring-2004 SKim
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
31
Other non-consumable electrodeprocesses
1048708 Plasma arc welding1048708 very higher energy concentration (33000oC) high feed rate 120-1000 mmmin arc stablility less thermal distortion deep penetration (keyhole technology)1048708 Laser beam welding electron beam welding etc
2008-spring-2004 SKim
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
32
Resistance Welding
1048708 Spot seam projection welding1048708 High current through the weld 3000A-100000A (05 ndash 10 V)
1048708 Extremely high heat flux (105 Wcm2)1048708 Heat generated H=i2Rt K (K=efficiency)1048708 Ex 5000 A 5 mm dia elctrodes two 1mm thick steel plates1048708 Effective resistance 200 Ω Then H= 500 J1048708 Nugget volume 30 mm3 mass 024 g 1400 Jg needed to melt1048708 336 J for melting lt 500 J
2008-spring-2004 SKim
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
33
Resistance welding
1048708 Spot welding Sequence1048708 Pressure on1048708 Current on1048708 Current off1048708 Pressure off1048708 Projection welding
2008-spring-2004 SKim
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
34
Solid-state interatomic bonding
1048708 Ultrasonic1048708 Oscillating tangential shear + static normal forces1048708 10KHz to 75 KHz1048708 Shear rarr plastic deformationrarr breaking up top layer (contaminated) rarr inter-atomic bond1048708 Friction1048708 Rotational part (at least one) flash1048708 Diffusion1048708 Goldsmiths bonded gold over copper1048708 Diffusion T gt 05 Tm1048708 Interface is the same as the bulk1048708 Fuselage frames
2008-spring-2004 SKim
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
35
Weld quality and defects
1048708 Porosity 1048708 Trapped gases contaminants 1048708 Preheat or increase rate of heat input1048708 Reduce speed allowing gas to escape cleaning1048708 Slag inclusions1048708 Oxides fluxes electrode coating trapped in weld zone1048708 Clean weld bead during multi-weld processes1048708 Provide enough shielding gas
2008-spring-2004 SKim
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
36
Weld quality and defects
1048708 Incomplete fusionpenetration1048708 Preheat and clean joint 1048708 Clean weld area enough shielding gas1048708 Change joint design or type of electrode
2008-spring-2004 SKim
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
37
Weld quality and defects
1048708 Cracks residual stresses1048708 Temperature gradients embrittlement of grain boundaries1048708 Inability of weld metal to contract during cooling
2008-spring-2004 SKim Kalpakjian
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
38
DFA - Welding
2008-spring-2004 SKim
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
39
DFM welding
2008-spring-2004 SKim
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult
40
Welding accessibility DFM
2008-spring-2004 SKim
Electrode must be held close to45deg when making these fillers
Easy to draw but the 2nd weldwill be hard to make
Easy to specifyldquoweld allaroundrdquo but hellip
Too close to side to allowproper electrode positioningMay be OK for average work butbad for leakproof welding
Try to avoid placing pipe joints nearwall so that one or two sides areinaccesible These welds must bemade with bent electrodes and mirror
Pipe
Wall
Easy
Very difficult