Friction Stir Welding -Recent Developments and Process Enhancements

Copyright © TWI Ltd 2010Technology Engineering

Friction Stir Welding - Recent Developments and Process Enhancements

• FSW Market Review• Challenges for FSW Users• Process Enhancements• Summary

Mike Russell TWI Ltd, Cambridge, UK<[email protected]> www.twi.co.uk

Presentation Contents:

AWS – New Welding Technologies


Friction Stir WeldingFriction Stir Welding

•• A rotating FSW tool is plunged between two clamped plates.A rotating FSW tool is plunged between two clamped plates.•• Friction between the tool and the plate material generates heatFriction between the tool and the plate material generates heat, ,

which causes a plasticised zone to form around the tool. which causes a plasticised zone to form around the tool. •• The rotating tool is then traversed, frictionally heating and The rotating tool is then traversed, frictionally heating and

plasticising material as it moves, forming a solidplasticising material as it moves, forming a solid--phase joint.phase joint.


Friction Stir WeldingFriction Stir Welding


FSW Market ReviewFSW Market Review


TakeTake--up of FSW by Industry up of FSW by Industry –– 1995 to 20091995 to 2009

0

50

100

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250

'95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '06 '07 '08 '09

FSW Licences Issued FSW Licences Issued



• Fast and successful transfer to first industrial use• Modest growth in users from 95 to 99, although

significant initial R+D efforts during this period• More rapid growth from 99 to 07, approx. +20 pa• Slower growth from 07 to 09, approx. +10 pa• Impact of Worldwide economic downturn?

⍄ Review challenges for new process adopters

TakeTake--up of FSW by Industry up of FSW by Industry –– 1995 to 20091995 to 2009



1. Start Up Costs– Equipment procurement and IP considerations

2. Process Flexibility– Some restrictions on materials and joint designs

3. Process QA and Certification– Standards, NDT and in-process QA

Challenges for new FSW adopters include: Challenges for new FSW adopters include:



1. Start Up Costs– Options for lower cost equipment and IP support

2. Process Flexibility– Developments in new materials and joint designs

3. Process QA and Certification– Progress on standards and in-process QA tools

Review challenges for FSW users and highlight new developments and process enhancements

This PresentationThis Presentation


Challenges for FSW UsersChallenges for FSW Users1. Start Up Costs1. Start Up Costs


• Equipment costs are usually the largest single source of expenditure for new FSW users

• Costs can be significant, e.g. around $0.5m for a standard mid range FSW system

• TWI offers support to new FSW users via:– Assistance in machine specification/procurement– Optimisation of FSW procedures for best results– Development of simple FSW tooling to allow use of

existing and/or lower cost machines

1. Start Up Costs1. Start Up CostsEquipment Costs


• The FSW IP landscape is complex and this can be a significant deterrent for potential process users

• TWI operates a flexible base FSW licensing approach designed to encourage wide scale use of the process

• TWI works closely with new process users to clarify their likely position in this somewhat confusing world

• TWI efforts to monitor FSW IP position are considerable

• Growth of the overall FSW community is of general benefit to all FSW process users and developers

1. Start Up Costs1. Start Up CostsIP Costs


Encouragement for new users – FSW benefits:• “improvement in Al fabrication (by FSW) has resulted in 15%

reduction in the man-hour per ton rate” - Hydro Aluminium, Norway• “FSW welds equal or better strength than MIG .. welding rods and

shielding gas not required .. distortion is only one twelfth of the distortion by MIG” - Hitachi Rail Cars, Japan

• “using prefabricated FSW panels has enabled a 40% increase in production capacity and turn-over at the yard“ - Fjellstrand, Norway

• "FSW specific design of Delta (satellite launch rockets) achieved 60% cost saving, and reduced manufacturing time from 23 to 6 days.“ - The Boeing Company, USA

• "FSW processing reduced assembly cost from 61% to only 19% of the total fabrication cost … total cost savings attributed to FSW (for a projected buy of 140,000 units) are $315 million.“ - AFRL, USA

1. Start Up Costs1. Start Up Costs


Technology Highlight Technology Highlight -- Development of Floating Bobbin Tool Development of Floating Bobbin Tool FSW to reduce equipment and fixture costsFSW to reduce equipment and fixture costs

1. Start Up Costs1. Start Up CostsZ

Axi

s co

ntro

l

25mm AA5083-O 25mm AA7075-T7


Floating Bobbin Tool FSW

Tool Holder

FixedBobbin

Tool

Component

Floating Bobbin FSW Developed using TWI exploratory fundingKey features:

• Low forces on fixture and machine• Simple control and tolerance to minor

part variations• Tolerant to minor component–machine

alignment variations• Simple tooling and no backing bar• Eliminates lack of penetration issues• Low distortion from uniform heat input



Floating Bobbin Tool FSWFloating Bobbin Tool FSW

6mm thickness AA6082-T6



Floating bobbin tool FSW in action at TWI on a low cost CNC milling centre (approx. $50k purchase cost)


Process enhancement allows use of lower cost machine tools


• Technology developed via TWI exploratory funding.

• Two year GSP now underway to further develop the technique and to assess applications.

• Work will target 2-12mm thickness 2xxx, 5xxx, 6xxx, and 7xxx series Al.

• Currently 8 sponsors signed up ($470k project)

Floating Bobbin Tool FSW – Group Sponsored Project



Challenges for FSW UsersChallenges for FSW Users2. Process Flexibility2. Process Flexibility


• Restrictions on possible workpiece materials are being addressed via significant R+D on tool technology, both at TWI and at many research centres throughout the World

• FSW of Cu now established in production, FSW of Steel is becoming a production reality, FSW in Ti is getting close, FSW of Ni and other high temp. alloys is being explored

• TWI is working on a range of new process variants, such as Stationary Shoulder FSW, which open up new possibilities in terms of materials and joint designs

2. Process Flexibility2. Process Flexibility

FSW can not be used for everything (yet):


Progress on hybrid Progress on hybrid WReWRe--PCBN tools for FSW of steel PCBN tools for FSW of steel (and other high temperature materials) (and other high temperature materials) –– TWI CRP workTWI CRP work


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PCBN(MS80)

W-Re/cBN(Q60)

W-Re/cBN(Q80)

W-25%Re-2.4HfC

(Triflute)

W-25%Re-9.1HfC

(Triflute)

W-25%Re(Triflute)

W-25%Re(Triflute)

Pre-heated

W-25%Re(PlainDome)

W-25%Re-2.4HfC(PlainDome)

W-25%Re-9.1HfC(PlainDome)

Wel

d Le

ngth

(m)

FSW tool life - 6mm 304L


Development of Stationary Shoulder FSW for high Development of Stationary Shoulder FSW for high temperature, low conductivity, workpiece materialstemperature, low conductivity, workpiece materials


•• The FSW probe rotates The FSW probe rotates through a stationary through a stationary shoulder/slide component.shoulder/slide component.

•• The nonThe non--rotating shoulder rotating shoulder component adds no heat component adds no heat to the weld surface.to the weld surface.

•• The resulting heat input The resulting heat input profile is basically linear.profile is basically linear.

•• This approach is of great This approach is of great help in the welding of low help in the welding of low conductivity materials.conductivity materials.Copyright © 2005, TWI Ltd. Patent Pending


Stationary Shoulder FSW of Ti AlloysStationary Shoulder FSW of Ti Alloys



Development of Stationary Shoulder FSW for corner joints Development of Stationary Shoulder FSW for corner joints and Tand T--Section parts in Al alloysSection parts in Al alloys


FSW Tool

Contoured Stationary Shoulder

Part

Part


Stationary Shoulder FSW of TStationary Shoulder FSW of T--Section joints in Al alloysSection joints in Al alloys

Tee Configurat ion

AA6082-T6 T-section joint



SSFSW of TSSFSW of T--Section joints in Al alloys with filletSection joints in Al alloys with fillet

AA7075-T6 rib to AA2014-T6 plate t-section weld with fillet material



Development of Stationary Shoulder FSW for corner joints Development of Stationary Shoulder FSW for corner joints and Tand T--Section joints in Al alloys Section joints in Al alloys –– Future WorkFuture Work


• SSFSW Technology developed via TWI internal exploratory funding

• New two year Group Sponsored Project (GSP) being launched now to further develop and assess the corner joint welding technique

• SSFSW for corner T-section joints will be developed for industrial applications

• Project plan based on six sponsors companies, for further information please contact TWI


Challenges for FSW UsersChallenges for FSW Users3. Process QA3. Process QA


• Active participation in FSW standards development: AWS D17.3, ISO 25239, IIW SC3B WG-B4 (FSSW)

• Industry led efforts, TWI support via internal funding

• Development and demonstration of NDT methods for FSW, both in general (TWI CRP work) and for specific cases (via dedicated project work).

• Development of new in-process QA technology via TWI’s CRP, collaborative and GSP work

TWI efforts to facilitate FSW adoption: TWI efforts to facilitate FSW adoption:

3. Process QA3. Process QA


TWI led collaborative project 03TWI led collaborative project 03--06 to develop 06 to develop LowStirLowStir: : Low Cost On Line FSW monitoring systemLow Cost On Line FSW monitoring system



Latest work Latest work -- Development of ARTEMIS: Detailed On Line Development of ARTEMIS: Detailed On Line FSW monitoring, QA and process development systemFSW monitoring, QA and process development system


ARTEMIS

Advanced Rotating Tool Environment Monitoring and

Information System

• Instrumented FSW tool system• Real time monitoring and

recording of key FSW variables


Latest work Latest work -- Development of ARTEMIS: Detailed On Line Development of ARTEMIS: Detailed On Line FSW monitoring, QA and process development systemFSW monitoring, QA and process development system


ARTEMIS monitors:

• Tool Rotation Speed• Process Torque• Downforce• Tool Temperatures• Max. Traverse Force• Tool bending forces at

7.5° intervals around tool circumference


ARTEMIS data output ARTEMIS data output –– On Line QA modeOn Line QA mode


Artemis MX Triflute

0100200300400500600700

0 50 100 150 200 250

Time (secs)

Torq

ue (N

m),

Rota

tion

Spee

d (rp

m)

05101520253035

Forc

e (k

N)

Torque Tool Rotation Speed Downforce

Artemis MX Triflute

0

0.5

1

1.5

2

0 50 100 150 200 250

Time (secs)

Forc

e (k

N)

0

100

200

300

400

500

Tool

Tem

pera

ture

(°C

)

Traverse Force (kN) Tool Temp (°C)




Good Weld Weld containing voids (JL gap) – size 250μm

voids

Average maximum recorded force per channel gives a footprint plot of material flow around tool




ARTEMIS output –On Line QA mode

Average maximum recorded force per channel results for test sample with 1mm and 2mm joint line gaps


ARTEMIS data output ARTEMIS data output –– Development modeDevelopment mode


Plain Cone Threaded Cone Triflute™ MX-Triflute™


ARTEMIS data output ARTEMIS data output –– Development modeDevelopment mode


Plain Cone MX-Triflute™

• Instantaneous plots show forces developed by FSW tools in action

• A whole new level of process information can be obtained

• Tool feature effects can be quantified and compared

• Evolution and oscillation of tool forces can be studied

• Tool loading regime can now be accurately determined and linked into process modelling efforts

• FSW process can be optimised in detail for individual applications


Development of ARTEMIS: On Line FSW monitoring, QA Development of ARTEMIS: On Line FSW monitoring, QA and process development system and process development system –– Future WorkFuture Work

• ARTEMIS Technology developed via TWI internal Core Research Programme (CRP) funding

• New two year Group Sponsored Project (GSP) to start in 2011 to assess and demonstrate the system for On-Line QA and process development

• Single client investigations already underway on tool optimisation and performance improvement

• For further information please contact TWI



SummarySummary


1. Start Up Costs– Set up costs are reducing as the process matures– IP is not an insurmountable barrier for new adopters

2. Process Flexibility– New options and opportunities for workpiece material

and joint types/designs are being developed3. Process QA and Certification

– Standards becoming established in user community– On Line QA tools are now becoming available

Encouragement for new FSW adopters: Encouragement for new FSW adopters:

SummarySummary


Conclusions and Final Thoughts: Conclusions and Final Thoughts:

SummarySummary

• The costs and risks associated with adoption of FSW are reducing and uptake of the process is increasing

• New opportunities are becoming available for new and existing process users via process enhancements– Floating Bobbin Tool FSW– Stationary Shoulder FSW– ARTEMIS On Line QA Technology

• The final ongoing challenge is communication, there are still many potential users in the World who don’t know about FSW – efforts continue to spread the word

Documents

Friction Stir Welding -Recent Developments and Process Enhancements