The aerospace industry is renowned for its relentless pursuit of innovation and excellence. From designing intricate aircraft systems to manufacturing robust spacecraft components, the sector is always on the lookout for new techniques and technologies that can enhance efficiency, reduce costs, and improve product quality. Joining aluminum sheets to create components with a high structural strength-to-weight ratio is vital to a craft’s quality and durability. Traditional methods like resistance spot welding and riveting have served the industry well, but a new technology is emerging – Refill Friction Stir Spot Welding or RFSSW. Invented at Helmholtz-Zentrum Geesthacht in Germany, this method promises numerous benefits for aerospace applications.

RFSSW has many advantages over traditional sheet metal joining methods – such as riveting and resistance spot welding- often used in the aerospace industry. It provides a higher joint strength and eliminates the need for rivets. Also known as Refill Spot Welding, RFSSW also has a lower heat input, reducing the amount of warping and distortion in the joined aluminum parts.

What is RFSSW and how does it replace rivets?

RFSSW provides a process better suited to aluminum alloys and replaces mechanical fastening with a zero-part-count method.

Refill Spot Welding offers:

  • Solid-state joining – no shielding gas required
  • Mechanical disruption of the oxide-covered surfaces
  • Single setup for different thicknesses
  • Capable of joining dissimilar materials
  • Low cycle time – sub-one-second in some alloys/thickness

Key features that distinguish Bond Technologies’ RFSSW machines are higher torque, faster speed, and an advanced control system. Bond worked collaboratively with researchers and industry members to identify features needed for the success of this process in the aerospace industry. Bond’s deep understanding of solid-state processes translates into superior equipment design. Bond’s RFSSW head can be used in a fixed mount stationary configuration or as an end-of-arm tool for robotic applications.

How does Refill Spot Welding work?

A fully automated welding cycle creates a weld in three steps:

  • The non-rotating clamping ring compresses the work pieces.
  • The rotating shoulder and probe contact the part, then the shoulder presses into the part as the probe retracts, disrupting the sheet interface.
  • The shoulder and probe then reverse directions, returning to the original part surface.

Refill 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, the process does not liquefy the workpiece, as the source of heating depends on resistance to relative motion. The solid-state nature of the process produces all its desirable characteristics, including excellent strength and crack resistance. To date, aluminum is the most practical material of choice.

Benefits RFSSW for Aerospace Manufacturing

High-Quality Welds

RFSSW produces defect-free welds with excellent mechanical properties. Unlike conventional spot welding, which can lead to weak spots due to the melting and solidification of metal, RFSSW ensures consistency and strength across the entire joint. This is critical in the aerospace industry, where the integrity of every weld affects the overall durability of the craft.

Superior Material Compatibility

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 could not 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.

Environmental Friendliness

RFSSW is a green technology. It doesn’t produce harmful emissions or waste products, making it an environmentally friendly choice for aerospace manufacturing. Carbon footprint and energy consumed are lower than other methods used to join sheet metal. This aligns with the growing emphasis on sustainability within the industry.

Let Bond Technologies help you find the best Refill Friction Stir Spot Welding solution for your application.

Bond Technologies offers a full line of friction stir welding (FSW) machines, FSW tools & accessories, custom engineering solutions, and a host of services to help you integrate FSW technology into production.

Request a quote on your project by emailing or contacting us here.