The Seventh aiCAMstir Meeting was held online on 26 January 2023 with 32 attendees.
Agenda
The agenda of the 90 min long on-line meeting was as follows:
- Welcome and introduction (2-3 sentences each)
- Development of a new stitch friction stir welding gun and mechanical behavior of intersecting stitch welded AA 6016-T4 sheets. Dominik Walz, MPA Stuttgart, Germany (20 min + 5 min questions)
- Effect of FSW tool geometry on the joint quality of AA2024-T3/AA7075T6 joints in butt configuration. Reza Beygi, INEGI, Porto, Portugal (20 min + 5 min questions)
- Machine investment cost and tool wear of friction stir welding of battery trays of compact crossovers. Stephan Kallee, AluStir, Germany (20 min + 5 min questions)
- Collaborative projects, organisational comments and date of next meeting (25 May 2023). Mike Lewis (FTS Engineering Answers Ltd)
Presentations
Development of a new stitch friction stir welding gun and mechanical behavior of intersecting stitch welded AA 6016-T4 sheets. Dominik Walz, MPA Stuttgart, Germany
Kevin Colligan (CTC, Concurrent Technologies Corporation):
Analysis of Torque Data from Friction Stir Welds in Aluminum
Effect of FSW tool geometry on the joint quality of AA2024-T3/AA7075T6 joints in butt configuration. Reza Beygi, INEGI, Porto, Portugal
R. Beygia (Institute of Science and Innovation in Mechanical and Industrial Engineering (INEGI), Rua Dr. Roberto Frias, 4200-465 Porto, Portugal) and LFM da Silva (Department of Mechanical Engineering, Faculty of Engineering of the University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal):
Effect of FSW Tool Geometry on the Joint Quality of AA2024-T3/AA7075-T6 Joints in Butt Configuration. Seventh aiCAM
stir meeting, 26 January 2023
Content. Introduction, Method, Results and discussion, Conclusion
Introduction: Applications AA2024 and AA7075 alloys: Aerospace industry (wing, fuselage, outer panel structure), Advantages of these alloys, Weight reduction, High fatigue strength, Challenges of joining of these alloys by fusion welding processes, Solidification cracking, Distortion
Machine investment cost and tool wear of friction stir welding of battery trays of compact crossovers. Stephan Kallee, AluStir, Germany
Stephan Kallee, AluStir:
Machine investment cost and tool wear of friction stir welding of battery trays of compact crossovers
VW and Ford: Compact Crossovers, Sandy Munro: „Some really fancy extrusions with some fancy welding and some fancy machining“, „Integrate the battery structure into the vehicle, having the battery and body work together“, Modular approach, Cost optimized materials, joining processes and interfaces
Alu
Stir Battery Tray, 1.3 x 1.7 m floor plate, Made from hollow aluminium extrusions, 14 parallel friction stir welds: 22 m weld length Cut off the start and stop or park the end hole in a suitable place, Benchmarking study is based on producing trays for 200,000 cars per year in Europe, 100 sec per car
Quality and Cost: aiCAM
stir Software, The vision is to develop a software-package that adjusts the parameters automatically based on CFD, analytical modelling, parameter monitoring, image analysis and non-destructive testing, aiCAM
stir Ontology, To predict the quality and cost of FSW based on parameters, variables and boundary values
VW ID.4: Munro and Sabic, Necked 8.8 bolts, stretched by a torque wrench („it would take an act of congress, to change that”), Flow Drill fasteners, Anaerobic serpentine seals, Interlayers against galvanic corrosion
Flow Drilling: Weber, System 46,000-48,000 € + 350 kg payload robot, Spare parts, IP 12 „bit“ at 17-20 € for 200,000-300,000 parts Brackets for 500,000-800,000 parts, Fasteners, 2×18 + 2×23 = 82 per car, 0.03, 0.10 or 0.15 €
Flow Drilling: Weber and OTC etc
FSW (friction stir welding)
FSW: Ideal for Aluminium, Low distortion, Very reliable process, Use high quality extrusions with good tolerances, Use rigid machines with sophisticated force and position control, Good clamping required, To be welded from one side using a mechanical interlock or from both sides simultaneously, Run-on and run-off tabs are possible
Gantry, CNC-Cell or Robot? Welding speed > 3m/min (up to 5 m/min) depends on rigidity and pin length. Bespoke FSW machine or converted milling machine? FSW and CNC milling in the same fixture? High performance gantry machines for EV battery trays
FSW Tools: Wear Mechanisms, Adhesion (tribological reactions): pits and notches (scoring), Diffusion (embrittlement and fatigue): shearing off the pin. Recommendations, Avoid notch between pin and shoulder, Use Triflat instead of Triflute, Reduce the rotation speed, Increase pin diameter, Keep shoulder diameter as small as possible, Use harder materials, Use coatings
Three cells with a total of six FSW machines are required for 200,448 cars/year
MIG Welding (metal inert gas welding)
Ford Mach-E: Munro: MIG welding, Variation LHS-RHS: robotic and manual or differently programmed, End-crater parked away from the highly stressed zone, Burn-in at the weld start, Consistency and accuracy are required, MIG welding of aluminium is more difficult than MAG welding steel, because you cant see the temperature, Production ramp-up is complicated and expensive
Ford Mach-E: Nemak, 2 Fanuc robots, 2 MIG welding kits, 1 positioner, Simple automated hydraulic fixtures
OTC MIG Welding, 2 OTC FD-B6L, 1 OTC FD-V166
Market Segments: Battery enclosure mate-rials of current vehicles, The majority of long range BEVs in current production worldwide use aluminum as the main material for the battery enclosure, However, dissimilar material combinations are getting increasingly attractive
Benchmarking: Munro and Sabic, Expensive tooling for die casting of aluminium, Most OEMs have excellent foundries and want to keep their staff employed, Tray and Total Assembly made from Plastics, Battery Tray: 72 kg vs. 43 kg: Δ 29 kg (weight saving by using plastic), Total Assembly 489 kg vs. 427 kg: Δ 62 kg (cost saving by using plastic)
LME (London Metal Exchange): Premiums and Discounts, According to a rule of thumb, the cost of FSW-specific aluminium 6000 series extrusions is about LME + Premium + 1.0-1.2€/kg
Cost Comparison: Not included, Labour, maintenance and training, Factory building, Sawing and collating of extrusions, Pressure testing, Adhesives and paints, Material storage and handling, Development, crash and fire testing
Benchmarking: Conclusions, An empty battery tray costs approx. 480 €, FSW is very cost effective: 0.69 €/m, The material costs for the aluminium extrusions are the main cost factor, Dissimilar material combinations are often beneficial
A video recording of this online meeting is available via the following link:
Literature
Next meeting
We want to invite you to attend the Eight online aiCAMstir Meeting on using artificial intelligence in Computer Aided Manufacture of friction stir welds. The meeting will be held on Thursday, 25 May 2023, 16:00 - 17:30 (London), as shown on upcoming events.
Please contact stephan.kallee@alustir.com, if you want to attend the meeting and/or if you want to participate in the project.