COME TALK WITH THE WORLD EXPERTS IN SOLID STATE PROCESSING
Bond at FABTECH Chicago | Sept. 8–11 | Booth #B17039 with KUKA | RFSSW on a KUKA Robot!
Bond at FABTECH Chicago
Sept. 8–11 | Booth #B17039 with
KUKA RFSSW on a KUKA Robot!
Refill Friction Stir Spot Welding (RFSSW) is transforming the way aluminum sheets are joined. RFSSW has many advantages over traditional sheet metal joining methods of riveting and resistance spot welding.
It provides a higher joint strength than resistance spot welding and eliminates the need for rivets. RFSSW also has a lower heat input, reducing the amount of warping and distortion in the joined aluminum parts.
Invented at Helmholtz-Zentrum Geesthacht (HZG) in Germany, with whom Bond has a working partnership, RFSSW is rapidly gaining traction in Aerospace and Automotive applications. Bond has taken the lead in advancing RFSSW technology, developing a robust RFSSW machine that surpasses performance expectations.
RFSSW 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 Friction Stir Spot Welding (FSSW) to make spot welds. FSSW fundamentally leaves a keyhole, which reduces its strength.
Helmholtz-Zentrum Geesthacht (HZG) in Germany, with whom Bond has a working partnership, developed and patented their RFSSW technology as a way to address the exit hole left in the FSSW weld, and they have shared this patented technology with Bond for the creation of production RFSSW systems.
Aluminum sheets are commonly used in aircraft fuselages, automotive body panels, and various other products where a high strength-to-weight ratio is essential. Traditional joining techniques like rivets or resistance spot welding have limitations in terms of strength and efficiency, prompting the need for innovative solutions like RFSSW.
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 lightweight system, capable of higher force, torque and speed than has been possible previously.
Bond collaborated closely with researchers and industry experts to develop an RFSSW machine that meets the demanding requirements of modern manufacturing. The result is a robust, repeatable RFSSW system that brings higher performance and lower costs to the Automotive industry and other industries working with aluminum alloys.
The key features of Bond’s RFSSW head, including higher torque, faster traverse speed, and an advanced control system, set it apart from other systems on the market. Whether used in a fixed mount stationary configuration or as an end-of-arm tool for robotic applications, Bond’s RFSSW head delivers superior performance and reliability. Bond’s RFSSW technology is revolutionizing the way aluminum sheets are joined, offering unmatched strength, efficiency, and versatility.
RFSSW has been proven to produce joints with excellent tensile and fatigue strength, often surpassing the capabilities of current methods. It can effectively join aluminum alloys in the 2XXX, 5XXX, 6XXX, and 7XXX series families, making it a versatile solution for a wide range of applications. Additionally, RFSSW offers cycle times as low as 600ms per weld, ensuring efficient production processes.
RFSSW is especially suitable for joining lightweight, high-strength materials such as aluminum alloys, which are commonly used in aerospace applications. Refill Spot Welding demonstrates its potential to weld dissimilar materials such as copper and aluminum, which could open doors to new applications. For instance, it can weld copper or aluminum electrical contacts to aluminum frames, where rivets cannot be used.
Traditional welding methods often struggle with these materials due to high heat input and resultant distortions. RFSSW, on the other hand, operates at lower temperatures, reducing heat distortion and maintaining the integrity of the material.
Refill Friction Stir Spot Welding is similar to conventional Friction Stir Welding in the way that heat and deformation are produced. The process relies on friction and plastic work produced by relative motion between a non-consumable tool set and a workpiece. As a result, it is undesirable to liquefy the workpiece since the source of heating depends on resistance to relative motion. The solid-state nature of the process produces all of its desirable characteristics.
In the RFSSW process, three concentric tooling components are used to plasticize and mix two (or more) overlapped sheets of metal. To date, aluminum is the most practical material of choice.
An outer clamp ring is non-rotating, pressing down to secure the top sheet to its substrate. A shoulder, which is also a ring, and a probe, which is a cylinder within the shoulder, rotate together and move down flush with the surface. The shoulder and probe spin and push to generate frictional heat, whereupon the shoulder descends into the sheet while the probe retracts.
This combined vertical motion allows plasticized material to be displaced from the shoulder area into the volume created by the probe. Once the shoulder is at full depth, which approximates the top sheet thickness, the top and bottom sheet materials become mixed together. Then, the process reverses the shoulder, and the probe returns to a position flush with the top surface. What results is a top and bottom sheet that are joined by a circle the size of the shoulder outer diameter and a smooth top surface.
Refill Friction Stir Spot Welding (RFSSW) is incredibly fast—typically under one second per weld. This video has been slowed down to give a closer look at the precision and efficiency of the process.
RFSSW provides a process better suited to aluminum alloys and replaces mechanical fastening with a zero-part-count method. It offers several advantages over rivets or resistance spot welding:
Plastic deformation refines the grain structure, enhancing material strength.
Top sheet thickness can vary using different program parameters, providing flexibility in design.
One set of tooling can accommodate multiple sheet thicknesses.
Friction and plastic deformation generate heat, improving energy efficiency.
The refined microstructure offers high resistance to crack propagation, ensuring good fatigue strength.
No consumables are required, aside from periodic tool replacement.
Sub-one-second in some alloys/thickness.
If you’re unsure whether RFSSW is suitable for your application, our team is here to help. We specialize in identifying new applications and solutions for our customers, ensuring you get the best results from FSW technology.
For customer service questions, call us directly at +1 (574) 327-6730.