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Technology explainer
What Is Friction Stir Welding (FSW)?
A solid-state joining process that stirs two pieces of metal together with a rotating tool, without melting either one.
In short: Friction stir welding (FSW) joins metal below its melting point. A rotating tool plasticizes the metal on both sides of the seam and stirs it together, leaving a wrought, fine-grained joint with no melt pool, no filler, and no shielding gas.
How it compares
Friction Stir Welding Next to Arc Welding
| Feature | Friction stir welding | Arc (fusion) welding |
|---|---|---|
| Melts the metal | No | Yes |
| Filler and shielding gas | Neither is needed | Typically required |
| Porosity and hot cracking | None from a melt pool, because there is none | Can occur as the weld solidifies |
| Distortion | Minimal, so little post-weld straightening | More heat input, so more distortion |
| High-strength 2xxx, 6xxx and 7xxx alloys | Routine to weld | Many crack under fusion welding |
| Dissimilar metals | Joins combinations such as aluminum to copper | Often cannot be fusion welded |
How it works
A Joint Made Below the Melting Point
- The pieces to be joined are clamped edge to edge.
- A rotating tool is pressed into the seam and travels along it. Friction heats the metal until it softens, but it never melts.
- The tool stirs the softened metal from both sides together. As it moves on, the stirred metal cools into a continuous, fine-grained joint.
The process was developed at TWI in the United Kingdom in the early 1990s and is now standard on aerospace hardware, where long fatigue life and proven cryogenic service matter.
Where it is used
Where Friction Stir Welding Earns Its Place
Friction stir welding is used for structural and pressure-containing joints in aluminum weldments, liquid cooling cold plates and heat exchangers, EV battery trays, large aluminum vacuum chambers, flight hardware joints qualified to AWS D17.3 and NASA specifications, and hull structures and tailored welded blanks for maritime programs.
For your program
From Your Drawing to Production
You send LeapFast the drawing. LeapFast tunes the process for your material and joint, qualifies it to AWS D17.3, a NASA specification, or your own, welds a first article from your drawing, and then runs low-rate and high-rate production on the same qualified process. You do not need to buy a friction stir machine.
Questions
Friction Stir Welding, Answered
What is friction stir welding?
Friction stir welding is a solid-state process that joins metal by stirring it together with a rotating tool, below its melting point. The result is a wrought, fine-grained joint without the porosity or hot cracking that can come with a melt pool.
Is friction stir welding stronger than arc welding?
Friction stir joints are substantially stronger than arc welds in aluminum, with long fatigue life, minimal distortion, and proven cryogenic service.
What metals can friction stir welding join?
It joins aluminum and other metals, including high-strength 2xxx, 6xxx, and 7xxx alloys that crack under fusion welding, and dissimilar combinations such as aluminum to copper.
Does friction stir welding need filler metal or shielding gas?
No. The metal is joined without filler, without shielding gas, and without post-weld straightening.
What is AWS D17.3?
AWS D17.3 is the American Welding Society specification for friction stir welding of aluminum alloys in aerospace applications. LeapFast qualifies friction stir welding procedures to AWS D17.3, to NASA specifications, and to customer-furnished specifications.
Do I need to buy a friction stir welding machine?
No. You send LeapFast a drawing, LeapFast welds the part, and the part is shipped back to you. LeapFast does not sell machines.
How is friction stir welding different from B-FSD?
Friction stir welding joins pieces of metal together. Bobbin Friction Stir Deposition builds up new metal in passes to form a structure. Both are solid-state processes that run on friction stir equipment.
Got a Part Holding Up Your Program? Send It to Us.
A drawing, a STEP file, or a sketch and a size is enough. You will hear back within 3 business days.