Friction Stir Welding: What is it and How Does it Work?
Lauded as the most significant innovation in metal joining in the last decade, Friction Stir Welding (FSW) introduces a solid-state joining process that is environmentally friendly, versatile, and energy efficient. FSW outperforms conventional fusion welding by joining aerospace aluminum alloys, and other metallic alloys, that are high-strength. The significance of this advancement is that aerospace aluminum alloys, like 2XXX and 7XXX series, have been classified as virtually non-weldable with conventional welding processes because of porosity and microstructure solidification behavior. Resistance welding can be performed on aluminum alloys, however, surface preparation has to be performed, which is expensive and surface oxide becomes a problem.
How Friction Stir Welding Works
Simplistic in its concept, FSW consists of a rotating tool with various shoulder and pin designs, traveling along the joint line. With a combination of downward force and tool rotation, the heating process and moving of material create the joint. The intense heating generates plastic deformation, which is material movement around the pin, resulting in recrystallized grains. Therefore, the movement of material by the pin produces a joint in solid-state. This process provides an improvement in material uses, too, by the ability to join metal of different aluminum alloys, composites, and thicknesses.
Environmentally Friendly Benefits of Friction Stir Welding
FSW, unlike its predecessors, is considered “green” technology. The FSW process consumes less energy, uses no cover gas or flux making it more environmentally friendly.
The energy benefits from this solid phase process allow for joining alloys of different thicknesses, reducing weight. Some of the additional environmental and energy benefits include:
- Elimination of solvents for degreasing
- Elimination of grinding wastes
- No surface cleaning required
- Requires 2.5 percent of the energy used in a laser weld
- Decreased fuel consumption in automobiles, aircraft, and ships where FSW is used
FSW is an ingenious concept for versatility, sustainability, and functionality. A method to join metals of different composites, and alloys, while maintaining excellent tensile and fatigue strength. Compounded with its energy efficiency and compatibility for automation and robot use, FSW provides a consistent weld for many industries.
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