As the name suggests, “friction stir welding” (FSW) is a metal joining technique that uses friction heat to unite metal structures. In traditional welding, high levels of heat are applied thereby melting two metal parts into one another. By contrast, FSW is a solid-state joining technique that takes advantage of metal atom’s cohesive forces that cause them to diffuse into each other. The friction generates temperatures below the melting point, but high enough where the plasticized material can move around.
The key in FSW is the non-consumable rotating tool. The tool, that looks similar to a drill bit, is made up of two components: a probe, a small cylinder which will penetrate into the width of the metals at their joint; and a shoulder, a larger cylinder which will spin along the surface of the metal pieces. The rotating tool supplies both the heat and the pressure needed for the weld.
The metal pieces are clamped tightly in a butt or lap joint configuration, and the mechanical rotating tool is programmed to run along the joint. The spinning tool inserted between the tightly clamped metal creates enough friction heat for the atoms of the two metals to move around. The plasticized metal moves around the probe and then fills the cavity behind the tool before coalescing into a single piece of metal.
What are the advantages of friction stir welding’s solid state joining for aerospace, shipbuilding, rail, aerospace, automotive industries?
There are various advantages to using FSW for metal joining:
Flexibility: FSW allows efficient welding for difficult projects. FSW can be used on high-strength aluminum that can be difficult to join using conventional welding. Companies such as Taber use FSW to create aluminum extrusions in a wide array of profiles and sizes ranging from micro extrusions to 65-foot long extrusions.
High strength welds: Traditional welding can introduce corruption into metals during the welding process, as it can manifest solidification cracks and porosity problems. Solid-state joining creates joints that are as strong as the metal from which they are created and are a good choice for high-strength aluminum.
High quality welds: Characteristics of FSW welded metal include low distortion, reduced weight (no filler material), and excellent bonding properties.
Green welding: Traditional welding consumes electrodes, energy, shielding gas, and produces noxious fumes. FSW with its non-consumable rotation tool eliminates waste.
Limitations of friction stir welding for metal joining:
The FSW spin tool must resist heat and corrosion as it moves the metal around it. Therefore, FSW best works with malleable materials with low welding temperatures.
Therefore, aluminum continues to be one of the most important metals used in FSW. Aerospace, shipbuilding, rail, aerospace, automotive industries all look to aluminum FSW for high-precision aluminum extrusions and aluminum welds of high strength and quality. Aluminum FSW is particularly important because high-strength aluminum can be difficult to join using traditional methods and FSW precision allows almost infinite variety in shape and size in aluminum extrusions.
More on Taber Extrusions
Founded in 1973, Taber Extrusions originally pioneered a process for extruding rectangular billets which enables the company to extrude solid profiles up to 31 inches wide or hollows up to 29 inches. Taber expanded with the purchase of an extrusion facility in Gulfport, MS in 1995 which houses a cast house and two additional presses, with a fabrication area that has been expanded multiple times. Besides their recently expanded capabilities to include micro-extrusions and 7” billet molds, Taber Extrusions is proud to announce friction stir-welding technology. The addition of in-house FSW capabilities creates a vertically integrated supplier of FSW panels and assemblies never before seen in North America.