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New Trends in Welding in the Aeronautic IndustryNew Trends in Welding in the Aeronautic Industry

Patricio F. Mendez (MIT/Exponent)

Thomas W. Eagar (MIT)

Patricio F. Mendez (MIT/Exponent)

Thomas W. Eagar (MIT)

Welding for Aeronautics is Growing!Welding for Aeronautics is Growing!

OutlineOutline

• Fundamentals• Physics• Economics

• Case studies• LBW• EBW• FSW

• Research at MIT

• Analysis of trends

• Fundamentals• Physics• Economics

• Case studies• LBW• EBW• FSW

• Research at MIT

• Analysis of trends

Ordering of welding processesOrdering of welding processes• The intensity of the heat source determines

most properties of the welding process.• The intensity of the heat source determines

most properties of the welding process.

102 104 105 106 107103

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practical range for welding

d/wefficiencyHAZ size

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Characteristics of aeronautical industryCharacteristics of aeronautical industry

• low unit production• high unit cost• extreme reliability• severe operating conditions

• low unit production• high unit cost• extreme reliability• severe operating conditions

Joining processes in aeronauticsJoining processes in aeronautics

• Bird’s eye view• Laser beam welding• Electron beam welding• Friction stir welding

• Bird’s eye view• Laser beam welding• Electron beam welding• Friction stir welding

Laser beam weldingLaser beam welding

• Concentrated heat source

• Can be done in open atmosphere

• Uses: A318, A380

• Concentrated heat source

• Can be done in open atmosphere

• Uses: A318, A380

Electron Beam WeldingElectron Beam Welding

• Concentrated heat source

• Must be done in vacuum

• Uses: F22, Titanium

• Concentrated heat source

• Must be done in vacuum

• Uses: F22, Titanium

Friction Stir WeldingFriction Stir Welding

• Solid-state process

• No need for shielding gas

• Uses: Eclipse, Space Shuttle

• Solid-state process

• No need for shielding gas

• Uses: Eclipse, Space Shuttle

Concentrated heat makes stronger weldsConcentrated heat makes stronger welds• Electron beam and laser beam make

stronger welds than arc welding• Electron beam and laser beam make

stronger welds than arc welding2219 alloy

Concentrated heat causes less distortionConcentrated heat causes less distortion• Electron beam welding and laser

beam welding melt much less than other processes• much less distortion• less metallurgical defects

• Electron beam welding and laser beam welding melt much less than other processes• much less distortion• less metallurgical defects

Electron beam GTAW

Solid state processes have no solidification defectsSolid state processes have no solidification defects• No cast structure, fine grain

• Friction Stir Welding• Can weld 7XXX stronger than 2XXX

• Diffusion Welding• Can weld Ti, not Al

• No cast structure, fine grain

• Friction Stir Welding• Can weld 7XXX stronger than 2XXX

• Diffusion Welding• Can weld Ti, not Al

1

10

100

1000

10000

100000

10 100 1000 10000 100000

Velocity [km/h]

Sav

ing

s p

er p

ou

nd

lig

hte

r [$

/lb

]

car$2/lb

airliner$200/lb

military jets$2,000/lb

rockets$20,000/lb

Velocity, weight, moneyVelocity, weight, money

The pursuit for weight reductionThe pursuit for weight reduction

• 10-15 tons lighter!• $5 million in fuel

savings over lifetime

• 10-15 tons lighter!• $5 million in fuel

savings over lifetime

Weight reduction in small planesWeight reduction in small planes

• Range increased 4%

• Savings ~ $7000/lb

• Range increased 4%

• Savings ~ $7000/lb

Beechcraft Baron 581395 kg

Eclipse 500 1225 kg

Weight reduction in space Weight reduction in space

• 2219 Al2195 Al-Li• 1% Li• 7500 lb weight savings• Essential to to get to the ISS• $75 million savings per launch

• 2219 Al2195 Al-Li• 1% Li• 7500 lb weight savings• Essential to to get to the ISS• $75 million savings per launch

Weight reduction in enginesWeight reduction in engines

• Compressors, fans• machined titanium,

composites, friction welded

• Hot sections• friction welded

inconel

• Compressors, fans• machined titanium,

composites, friction welded

• Hot sections• friction welded

inconel

Welding equipment is expensiveWelding equipment is expensive

• The cost of the equipment is proportional to the intensity of the heat source

• The cost of the equipment is proportional to the intensity of the heat source

Friction stir

Welding expenditures per unitWelding expenditures per unit

Total welding expenditures

Units produced in a year

Welding expenditures per unit

$2.5 billion

30 million ~$100

$200 million

2,500 ~$100,000

$50 million

100 ~$500,000

Proportion of welding expendituresProportion of welding expenditures

Labor costs are highest in aero industryLabor costs are highest in aero industry

Welding expenditures are smallest for aerospaceWelding expenditures are smallest for aerospace

Implications of welding economicsImplications of welding economics• Welders in aeronautics are highly qualified

• Proportion of welding expenses are small

Large window of opportunity for• process development• employment

Cost efficiency likely to increase with scale• Laser and friction stir welding cheaper than

riveting

• Welders in aeronautics are highly qualified

• Proportion of welding expenses are small

Large window of opportunity for• process development• employment

Cost efficiency likely to increase with scale• Laser and friction stir welding cheaper than

riveting

Case StudiesCase Studies

Laser Beam Welding: A318/A380Laser Beam Welding: A318/A380

• Riveting consumes 40% of man hours on structure

• LBW cuts time by half (8 m/min!)• Less expensive (fewer mfg steps)• Less corrosion (no holes, crevices)• Lighter (no sealing)• Stronger than rivets• Same fatigue life

• Riveting consumes 40% of man hours on structure

• LBW cuts time by half (8 m/min!)• Less expensive (fewer mfg steps)• Less corrosion (no holes, crevices)• Lighter (no sealing)• Stronger than rivets• Same fatigue life

New StructuresNew Structures

•Skin sheet unaffected•Welding on both sides simultaneously

Electron Beam Welding: F-22Electron Beam Welding: F-22

• Aft fuselage • 90 m of EBW, 76 cast parts)

• Aft fuselage • 90 m of EBW, 76 cast parts)

Friction Stir Welding: Eclipse 500Friction Stir Welding: Eclipse 500

• 65% of riveted joints=30,000 rivets eliminated

• Welded:• Cabin, aft fuselage,

wings, and engine mounts

• Riveted:• Tail, longitudinal

fuselage joints, skins thinner than 0.040”

• 65% of riveted joints=30,000 rivets eliminated

• Welded:• Cabin, aft fuselage,

wings, and engine mounts

• Riveted:• Tail, longitudinal

fuselage joints, skins thinner than 0.040”

Friction Stir Welding: Eclipse 500Friction Stir Welding: Eclipse 500

• Welds three times stronger• Equal fatigue strength• Better corrosion properties• Riveting: 6 in/min• FSW: 20-40 in/min• $50,000-$100,000 savings per plane• Less factory space

• Welds three times stronger• Equal fatigue strength• Better corrosion properties• Riveting: 6 in/min• FSW: 20-40 in/min• $50,000-$100,000 savings per plane• Less factory space

Friction Stir Welding: Space ShuttleFriction Stir Welding: Space Shuttle

• GTAW• VPPA• FSW:

• solves purging problems• stronger

• GTAW• VPPA• FSW:

• solves purging problems• stronger

• Boeing made $15 million investment in FSW

• Delta rockets• (1st flight: Delta II

on 8/99)

Friction Stir Welding: BoeingFriction Stir Welding: Boeing

Friction Stir Welding: A380Friction Stir Welding: A380

• FSW• faster, stronger, better fatigue, less corrosion• Incompatible with Glare

• FSW• faster, stronger, better fatigue, less corrosion• Incompatible with Glare

Research at MIT: modelingResearch at MIT: modeling

• New modeling technique: OMS• Order of Magnitude Scaling• Can reduce number of experiments• Can give approximate solutions to

equations• Can generalize numerical or

experimental results

• New modeling technique: OMS• Order of Magnitude Scaling• Can reduce number of experiments• Can give approximate solutions to

equations• Can generalize numerical or

experimental results

Research at MITResearch at MIT

• Ceramic to metal joining

• TLP, patterned interfaces

• Ceramic to metal joining

• TLP, patterned interfaces

ceramic

metal

Research at MITResearch at MIT

• EBSFF (3D bodies without mold)• EBSFF (3D bodies without mold)

Startup: Semi-Solid TechnologiesStartup: Semi-Solid Technologies

• Fast manufacturing: SSM-SFF

• Semi-solid die-casting

• Semi-solid welding

• Fast manufacturing: SSM-SFF

• Semi-solid die-casting

• Semi-solid welding

39

• Cost and weight savings push for replacement of mechanical joining with welds

– DFW of Ti metal sheet (replacing Al)

– EBW of Ti structure in military aircraft

– LBW of Al skin and stringers in commercial aircraft

– FRW of blisks for military jet engines

– FSW of Al skin

now

furt

her

into

the

futu

reConclusions

(2000)

39

• Cost and weight savings push for replacement of mechanical joining with welds

– DFW of Ti metal sheet (replacing Al)

– EBW of Ti structure in military aircraft

– LBW of Al skin and stringers in commercial aircraft

– FRW of blisks for military jet engines

– FSW of Al skin

now

furt

her

into

the

futu

reConclusions

(2000)

39

• Cost and weight savings push for replacement of mechanical joining with welds

– DFW of Ti metal sheet (replacing Al)

– EBW of Ti structure in military aircraft

– LBW of Al skin and stringers in commercial aircraft

– FRW of blisks for military jet engines

– FSW of Al skin

now

furt

her

into

the

futu

reConclusions

(2000)

39

• Cost and weight savings push for replacement of mechanical joining with welds

– DFW of Ti metal sheet (replacing Al)

– EBW of Ti structure in military aircraft

– LBW of Al skin and stringers in commercial aircraft

– FRW of blisks for military jet engines

– FSW of Al skin

now

furt

her

into

the

futu

reConclusions

!!

(2000)

Conclusions (2002)Conclusions (2002)

• Rivets are being replaced by welding at a fast pace

• Welding is expanding its role in airplanes• From fuselage parts, to wings

• Use of welding will influence materials selection• Favors metals over composites• Development of high-strength Al alloys

• Rivets are being replaced by welding at a fast pace

• Welding is expanding its role in airplanes• From fuselage parts, to wings

• Use of welding will influence materials selection• Favors metals over composites• Development of high-strength Al alloys

Conclusions (2002)Conclusions (2002)• FSW is the focus of much attention• If Eclipse 500 is successful:

• FSW will increase role in airplanes• Boeing might use FSW rocket experience to

airplanes• Airbus might revive FSW plans

• For rockets• FSW replacing fusion processes• VPPA losing appeal• EB welding losing appeal (Russia)

• For jet engines• FSW not ready yet for Ti and superalloys• Linear friction welding used for military apps.

• FSW is the focus of much attention• If Eclipse 500 is successful:

• FSW will increase role in airplanes• Boeing might use FSW rocket experience to

airplanes• Airbus might revive FSW plans

• For rockets• FSW replacing fusion processes• VPPA losing appeal• EB welding losing appeal (Russia)

• For jet engines• FSW not ready yet for Ti and superalloys• Linear friction welding used for military apps.