Bond Technologies has taken on the task of producing a robust, repeatable Refill Friction Stir Spot Welding (RFSSW) system, which brings higher performance and lower costs to the automotive industry and other industries working with aluminum alloys. This new tool compares favorably with riveting and resistance spot welding as the methods of choice for automotive chassis welding.
“With this breakthrough, Bond now offers a performance and cost-competitive alternative to self-piercing rivets and resistance welding of aluminum sheets. Our Refill Friction Stir Spot Welding machine can be mounted to a robot or, as a stand-alone unit. Test results show that cycle time of less than one second are achievable for automotive aluminum sheets.”
–Dave Hofferbert, President of Bond Technologies
RFSSW vs. Friction Stir Spot Welding (FSSW)
RFSSW is a solid-state joining process developed and patented by our friends at Helmholtz-Zentrum Geesthacht (HZG) in Germany, with whom Bond has a working partnership.
The process was developed using the tools and techniques of friction stir welding (FSW) in a new way, making possible solid-state spot welds in aluminum alloys that are flush with the sheet, in contrast to earlier uses of FSSW to make spot welds. FSSW fundamentally leaves a keyhole, which reduces its strength. By independent manipulation of the probe, shoulder and clamping ring, both axially and rotationally, a solid zone of “stirred” material is created between the sheets, yielding higher strength. Like other friction processes, this weld has extremely high quality and repeatability, with proper controls.
Until now, the RFSSW process has been limited by the speed at which a weld can be made. Bond overcame this obstacle by designing a rigid, compact and light weight system, capable of higher force, torque and speed than has been possible previously. We also paid attention to the changeover time for tooling, reducing it to 30 seconds. Additionally, the Bond RFSSW machine is lighter and more versatile than other such devices.
Download our RFSSW Spec sheet
What sets Bond’s RFSSW machine apart?
- Rapid tool changeover
- Higher torque
- Higher RPM
- Faster cycle time
- Lighter weight
The RFSSW machine has been designed with high-volume production in mind but is just as comfortable in a research environment. It is perfectly suited for airplane structures and automotive aluminum sheet metal.
How RFSSW technology works
To address the main concerns with FSSW (a small weld area and remaining exit hole) HZG developed and patented their RFSSW technology, which they have shared with Bond for the creation of production welding systems.
Refill friction stir spot welding is a relatively new solid-state joining process which stands up as an alternative for producing overlap spot joints. The process uses a non-consumable tool consisting of two movable parts – pin and sleeve – mounted coaxially to a clamping ring.
In the first stage, the upper and lower plates are pinched together between the clamping ring and the backing anvil, while both the pin and the sleeve begin rotating. In the second stage, the pin and sleeve move in opposite direction to each other; one is plunged into the material while the other withdraws, creating a temporary reservoir, where the displaced material is held. Finally, axial motion reverses, pushing the plasticized material back where it began. The rotating pin and sleeve generate all of the heat in the process through solid-state plastic deformation, eliminating the need for shielding gas and filler metal.
Bond’s RFSSW machine for industrial uses
More traditional fastening techniques, such as clinching and riveting, are often costly and prone to corrosion issues. These processes are known for high operational costs from tooling and upkeep. Fusion-based spot welding techniques are prone to defects caused by solidification, making porosity and solidification cracking possible.
Implementing RFSSW into your production processes will mean cost savings, quality assurance and higher performance. If you have questions about incorporating RFSSW into your assembly line, contact Bond Technologies to discuss the best solutions for your product and industry needs.
Download our RFSSW Spec sheet
