AWS New Welding Technologies Friction Stir Welding - Recent Developments and Process Enhancements Presentation Contents: FSW Market Review Challenges for FSW Users Process Enhancements Summary Mike Russell <mike.russell@twi.co.uk> TWI Ltd, Cambridge, UK www.twi.co.uk
Friction Stir Welding A rotating FSW tool is plunged between two clamped plates. Friction between the tool and the plate material generates heat, which causes a plasticised zone to form around the tool. The rotating tool is then traversed, frictionally heating and plasticising material as it moves, forming a solid-phase joint.
Friction Stir Welding
FSW Market Review
FSW Market Review Take-up of FSW by Industry 1995 to 2009 250 200 FSW Licences Issued 150 100 50 0 '95 '96 '97 '98 '99 '00 '01 '02 '03 '04 '05 '06 '07 '08 '09
FSW Market Review Take-up of FSW by Industry 1995 to 2009 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
FSW Market Review Challenges for new FSW adopters include: 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
This Presentation Review challenges for FSW users and highlight new developments and process enhancements 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
Challenges for FSW Users 1. Start Up Costs
1. Start Up Costs Equipment 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 Costs IP 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 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 Costs Technology Highlight - Development of Floating Bobbin Tool FSW to reduce equipment and fixture costs Z Axis control 25mm AA5083-O 25mm AA7075-T7
1. Start Up Costs Floating Bobbin Tool FSW Floating Bobbin FSW Tool Holder Developed using TWI exploratory funding Key features: Component Fixed Bobbin Tool 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 FSW 1. Start Up Costs 6mm thickness AA6082-T6
1. Start Up Costs 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
1. Start Up Costs Floating Bobbin Tool FSW Group Sponsored Project 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)
Challenges for FSW Users 2. Process Flexibility
2. Process Flexibility FSW can not be used for everything (yet): 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 Flexibility Progress on hybrid WRe-PCBN tools for FSW of steel (and other high temperature materials) TWI CRP work 32 30 28 26 FSW tool life - 6mm 304L 24 22 Weld Length (m) 20 18 16 14 12 10 8 6 4 2 0 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 (Plain Dome) W-25%Re- 2.4HfC (Plain Dome) W-25%Re- 9.1HfC (Plain Dome)
2. Process Flexibility Development of Stationary Shoulder FSW for high temperature, low conductivity, workpiece materials Copyright 2005, TWI Ltd. Patent Pending The FSW probe rotates through a stationary shoulder/slide component. The non-rotating shoulder component adds no heat to the weld surface. The resulting heat input profile is basically linear. This approach is of great help in the welding of low conductivity materials.
2. Process Flexibility Stationary Shoulder FSW of Ti Alloys
2. Process Flexibility Development of Stationary Shoulder FSW for corner joints and T-Section T parts in Al alloys Part FSW Tool Contoured Stationary Shoulder Part
2. Process Flexibility Stationary Shoulder FSW of T-Section T joints in Al alloys Tee Configuration AA6082-T6 T-section joint
2. Process Flexibility SSFSW of T-Section T joints in Al alloys with fillet AA7075-T6 rib to AA2014-T6 plate t-section weld with fillet material
2. Process Flexibility Development of Stationary Shoulder FSW for corner joints and T-Section T joints in Al alloys Future 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 Users 3. Process QA
3. Process QA TWI efforts to facilitate FSW adoption: 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
3. Process QA TWI led collaborative project 03-06 06 to develop LowStir: Low Cost On Line FSW monitoring system
3. Process QA Latest work - Development of ARTEMIS: Detailed On Line FSW 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
3. Process QA Latest work - Development of ARTEMIS: Detailed On Line FSW 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
3. Process QA ARTEMIS data output On Line QA mode Artemis MX Triflute Torque (Nm), Rotation Speed (rpm) 700 600 500 400 300 200 100 0 0 50 100 150 200 250 Time (secs) 35 30 25 20 15 10 5 0 Force (kn) Torque Tool Rotation Speed Downforce Artemis MX Triflute Force (kn) 2 1.5 1 0.5 0 0 0 50 100 150 200 250 Time (secs) 500 400 300 200 100 Tool Temperature ( C) Traverse Force (kn) Tool Temp ( C)
3. Process QA ARTEMIS data output On Line QA mode Average maximum recorded force per channel gives a footprint plot of material flow around tool voids Good Weld Weld containing voids (JL gap) size 250μm
3. Process QA ARTEMIS data output On Line QA mode ARTEMIS output On Line QA mode Average maximum recorded force per channel results for test sample with 1mm and 2mm joint line gaps
3. Process QA ARTEMIS data output Development mode Plain Cone Threaded Cone Triflute MX-Triflute
3. Process QA ARTEMIS data output Development 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
3. Process QA Development of ARTEMIS: On Line FSW monitoring, QA and process development system Future 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
Summary
Summary Encouragement for new FSW adopters: 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 developed 3. Process QA and Certification Standards becoming established in user community On Line QA tools are now becoming available
Summary Conclusions and Final Thoughts: 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