Applications of Friction Stir Welding (FSW)
Introduction to Friction Stir Welding
The friction stir welding process was invented in 1991 making it a relatively new welding process. The first successful application was welding aluminum panels to aluminum extrusion. For many years after FSW was invented the process was slow to be used in commercial applications. After the 2000’s the marine industry relied on its advantages heavily and then shortly after so did the aerospace industry. More recently, the automotive industry has been utilizing the benefits of FSW. They are finding more and more ways to incorporate the technology in their manufacturing methods. Moreover, the outlook for friction stir welding looks very promising with accelerated growth. This is partly due to the increasing demand of making lighter and more complex parts while saving costs.
How FSW Friction Stir Welding Works
Friction Stir Welding uses a specifically designed FSW machine. The FSW machine has a CNC controlled spindle with a FSW tool attached to it. The tool is made up of two parts. First, there is a pin that drills into the materials to be welded. Second, is a shoulder that the pin is attached to. The shoulder diameter is larger in diameter than the pin. Next, the rotating tool is plunged onto the surface of the material and uses friction. The shoulder of the rotating tool rubs on the joint line of the work pieces creating a thermo mechanically affected zone (TMAZ). Consequently, the heat generated from friction causes the two materials to plasticize in the affected zone TMAZ. Finally, the downward pressure from the tool shoulder forges the two materials together along the joint line.
Since the materials are not heated to a liquid phase this is a solid state process. The properties of friction stir welded parts exhibit exceptional mechanical properties. One of the main benefit of using friction stir welding processes is the repeatability and easier quality control. FSW is a non consumable process which further reduces costs and increases the safety for the operators involved. Go here for more detailed information about friction stir welding. Below are some of the main applications of friction stir welding.
Friction Stir Welding FSW has been playing a more crucial role in the aerospace sector. Many manufacturers are using the exceptional benefits that FSW has to offer. One of the main manufacturers to adopt the technology is Boeing. Boeing first to use stir welding friction for building spacecraft. It is much easier to get approval for spacecraft versus commercial flight aircraft due to the lack of certifications required in the former. The fuel tanks which are the cylindrical domes on top are manufactured using welding stir friction. The material for the fuel tanks is aluminum and responsible for storing cryogenic O2. This is obviously a very critical part of the spacecraft and shows you the confidence level of FSW.
Airbus uses FSW to weld aluminum fuselage panels to stringers. They also are successful at welding different aluminum material frames together to create one solid structure. This process reduces the number of rivets and fasteners by thousands. Airbus has seen an increase in mechanical properties and a reduction of costs. In addition, smaller light jet manufacturers use friction stir welded parts to save weight. Another benefit is saving time from the mandatory inspections. With fewer parts there are fewer inspections that need to be completed. As you can see there is still a lot more potential for FSW in the aerospace sector. We expect to see its adoption steadily rise, but the main force keeping from really taking off is the regulations required.
The video below is a short video from NASA on how they incorporate FSW.
Ship building in the marine industry was one of the first applications to widely incorporate welding friction stir methods. It is primarily used for joining the aluminum alloy deck panels to the hull. Commercial ships are the primary users of FSW with the smaller vessels using it the most. Fishing boats use friction stir welding for joining aluminum structures to the freezer panels where the caught fish are stored. The welds keep their high strength characteristics even over very long seems making it the perfect application. Growth has been seen in the luxury small yachts industry for its lightweight characteristics. This benefits the yacht by saving fuel and increasing the cruising speed.
The video below is a basic illustration of friction stir welding a boat deck.
The auto industry is rapidly incorporating friction stir welding for joining structures together. It is commonly used for joining aluminum alloys together. This makes it a great application for welding aluminum panels to the chassis. Previously, this was one of the most difficult aspects of building a car chassis out of aluminum. Conventional welding techniques are too inconsistent leading to higher production times with a higher cost. Consequently, that is why cars using aluminum are higher end sports and luxury cars. Ford uses it to weld the center console tunnel in their Ford GT sports car.
Mazda uses a variation of friction stir welding called friction stir spot welding to weld the door panels together on their Mazda RX-8 sports car. Similarly, automotive manufacturers are attracted to the high strength and repeatability FSW provides. One of the more recent trends for using FSW in the auto EV industry. They use the process for bonding the battery panels together. For this reason, the designer can further optimize the battery for higher energy storage while simultaneously increasing the rigidity of the assembly.
The energy sector is one of the latest industries to use friction stir welding. Companies are using FSW to join dissimilar metals together for storing spent nuclear fuel rods. This significantly reduces the chance for nuclear radiation escaping from the high repeatability and quality of the welds. Moreover, the nuclear reactor itself can be designed for the FSW process to dramatically reduce costs and waste associated with conventional welding techniques. In conclusion, we are excited to see how this progress over the next ten years.