13 Main Advantages and Disadvantages of Friction Stir Welding | Applications of Friction Stir Welding
What Is Friction Stir Welding? |Advantages and Disadvantages of Friction Stir Welding |Applications of Friction Stir Welding | Benefits of Friction Stir Welding
What Is Friction Stir Welding?
Friction stir welding (FSW) is a solid-state joining method that employs a non-consumable tool to connect two facing workpieces without melting the workpiece material.
Friction between the revolving tool and the workpiece material produces heat, resulting in a softened area surrounding the FSW tool.
While moving along the joint line, the tool mechanically intermixes the two pieces of metal and forges the heated and softened metal by applying mechanical pressure, much like joining clay or dough.
It is typically used on wrought or extruded aluminum, particularly for buildings requiring extremely high weld strength.
Aluminium alloys, copper alloys, titanium alloys, mild steel, stainless steel, and magnesium alloys may all be joined using FSW. It was recently utilized effectively in polymer welding.
FSW has also recently achieved the connecting of incompatible metals such as aluminum to magnesium alloys.
FSW is used in contemporary shipbuilding, railways, and aerospace applications.
It was created and experimentally proved in December 1991 at The Welding Institute (TWI) in the United Kingdom. TWI has two patents on the method, the first of which was the most detailed.
TWI initially patented the FSW method in the majority of industrialized nations and licensed it to over 183 customers.
Friction stir welding and its variations, friction stir spot welding and friction stir processing, are utilized in the following industries: shipbuilding and offshore, aerospace, automotive, railway rolling stock, general fabrication, robotics, and computers.
Benefits of Friction Stir Welding
Friction stir welding has several benefits over traditional arc welding procedures. These are some examples:
- Friction stir welding, being a solid-state welding technique, is essentially fault free, with no hot cracking, porosity, or solidification fractures.
- Many ‘non-weldable’ aluminium alloys, such as those in the 2xxx and 7xxx series, can be joined. In most applications, no additional edge preparation is required.
- Because of the lower temperatures, the material being connected shrinks and distorts less.
- FSW is non-hazardous to the environment since it emits no fumes, splatter, or UV radiation.
- Machine tool technology is used, which makes the process easy to automate, extremely reproducible, and reduces the need for expert welders.
- Good mechanical characteristics, which are generally equal to or greater than those obtained by competitive techniques for aluminum alloys.
- Energy-saving
- There is no need for filler materials, flux, or shielding gases in aluminium alloys.
Advantages and Disadvantages of Friction Stir Welding
Friction stir welding offers a number of advantages and drawbacks over conventional arc welding processes.
Advantages of Friction Stir Welding
1. Friction stir welding produces high strength weld
Friction stir welding process uses a weld seam that is exceptionally robust and can sustain high mechanical stresses.
It is best suited when the connected workpieces and components will be utilized in structurally and safety-critical locations. Friction stir welding yields media- and pressure-tight connections with little warpage.
2. Minimal heat impact on the material
Friction stir welding produces little heat, which means that the welding process does not interfere with the alloy’s properties.
3. No distortion
Friction stir welding uses a slight rotating motion, with no external forces applied on the workpiece.
The process produces less distortion and a smoother joint. It also has a higher strength ratio than other processes, resulting in a stronger weld seam.
4. Energy-saving
Friction stir welding incorporates stainless steel rods that are almost impossible to damage. It produces a weld seam that is robust, promising a long-term service life for the welded joint.
The process is not affected by welding speed or welding cycle, and can be adapted for automated production techniques.
5. Automating and reducing manpower requirements
Friction stir welding processes are highly versatile and suitable for automation, making it possible to produce large quantities of parts using the same equipment.
6. No requirement for special edge preparation in most applications
Common aluminum alloys do not require edge preparation before welding and can be joined in-line, while still maintaining the same efficiency.
7. Media- and pressure-tight joints
FSW welds joints that are seam-free and with no porosity. It produces strong weld seams that are suitable for many applications like engine components, tanks, and boilers.
8. FSW is environmentally friendly
The process emits no fumes and has very low energy consumption. FSW welding eliminates the use of welding gases, fluxes, and shielding gas, thereby reducing costs and environmental impact
9. FSW is superior to other processes in welding Aluminium
Friction stir welding welds Aluminium on the whole without affecting its properties – for example, it does not alter alloys’ strength or hardness.
The alloy is welded without heating it causing stress-corrosion cracking.
10. Increased welding speed compared to conventional processes
The process produces fewer weld beads than the conventional process, reducing the welding cycle time while improving the mechanical characteristics of the weld.
11. High performance in tough conditions
The process is suitable for a wide range of joining tasks and it is adaptable to automated production techniques.
It ensures long-term reliability under difficult conditions like high temperature, low temperatures, high corrosion resistance and salt spray.
12. No need for filler wire or shielding gas
Friction stir welding is applicable to most aluminum alloys including light alloys.
Disadvantages of Friction Stir Welding
1. High initial or setup cost
The friction stir welding process has high initial cost. It requires special equipment and is not suitable for applications requiring standard equipment.
2. Low productivity
The process is not suitable for automated production since it takes longer than other techniques, leaving a large time gap between each weld bead.
3. Equipment costs are high for conventional facilities
Investing in a friction stir welding machine requires special technology-oriented equipment, which makes it expensive to implement in existing facilities.
New facilities require more capital investment than most other industrial processes.
4. Complicated or special fixture arrangement required
The process requires special fixtures and can only work with specially designed equipment.
5. It creates a visible hole in welding plates
Friction stir welding produces visible holes in the plates that are caused by the welding process. T
hese holes make it difficult for inspectors to evaluate weld quality and cause a lack of confidence when working with the plates.
6. Non Forgeable material cannot be weld
In order to weld a non-forgeable material, it must be able to withstand heat.
7. Noisier than other processes
The process produces a lot of noise, clanging and banging compared with other methods during the welding procedure.
8. Limited applications
Friction stir welding is suitable for aluminum alloys that are easily welded by conventional processes such as gas metal arc welding (GMAW). However, it is less flexible compare to arc welding process.
9. FSW cannot make filler joints
The process can only make insulated joints and cannot make in-line joint for the purpose of sealing.
10. The parts that are welded have a rough surface on the backside
The FSW process creates a rough surface on the back side of the weld, which makes it impossible to polish or harden after welding.
11. Low strength
Due to the required high shear stress on the contact surfaces, friction stir welding has a low strength in an alternating direction compared to conventional processes. Thus, it requires careful design and structural analysis of the parts prior to welding.
Applications of Friction Stir Welding
Friction stir welding is used for the welding of aluminium alloys, stainless steel, titanium, zirconium, nickel, and many other materials.
FSW is suitable for applications that require high strength and low maintenance such as aircraft parts (including fuel tanks), silos, cookers and boilers. Friction stir welding is also used in the production of these components
1. Marine applications
Friction stir welding is used to produce welded piping systems on gas-turbine engines.
2. Friction stir welding is used for fuel tanks
Friction stir welding is used to produce welded fuel tanks for marine boilers. Friction stir welding system with a very high workpiece feed speeds and high process control provide excellent condition of weld for fuel tank.
3. Friction stir welding in the production of silos and boilers
Friction stir welding is used in the production of silos and boilers. The welding process reduces the time of welding silo and boiler shells because it does not require the use of shielding gas and can be performed in-line.
4. Friction stir welding is used for the production of aircraft parts
Friction stir welding is used to build aluminium airframe components like empennage, leading edges, stabilizer fins, and nose landing gear doors.
Friction stir welding is also a preferred method to join fuel tanks to wing pylons.
5. Friction stir welding is used for the production of tanks
Friction stir welding is used in the production of tanks. It is not only a quick, but also a reliable method for welding aluminium for industrial and military applications
Friction Stir Welding FAQs
1. How does friction stir welding work?
A cylindrical shouldered tool with a profiled pin is rotated and plunged into the joint region between two pieces of sheet or plate material in friction stir welding.
The frictional heat between the wear-resistant welding tool and the workpieces softens them without causing them to melt, allowing the tool to move along the weld line without the need of shielding gas or filler wire.
Contact with the tool shoulder and pin profile forges the plasticized material transported to the trailing edge of the tool pin. When the workpieces cool, a solid phase connection is formed between them.
Here’s how step by step process on FSW technology works:
- A welding tool that rotates: A wear-resistant tool is rotated in a spindle.
- Placing: The tool is placed directly into the substance that will be welded.
- Feeding: Rotation generates frictional heat, causing the metal to become plastically malleable. The tool stirs it along the seam before compacting it without ever reaching its melting point.
- Elimination: The tool is pulled away from the seam. As a result, the workpieces have a robust, media- and pressure-tight joint.
2. What industries make use of friction stir welding?
Friction stir welding is utilized for aluminum applications in the following industries:
- Railroads
- Shipbuilding
- Automotive
- Transportation
- Offshore
- Power electronics
3. When is friction stir welding the best option for you?
FSW technique is especially excellent with metal. It enables the joining of aluminum alloys that were previously thought to be difficult or impossible to fusion-weld.
Friction stir welding is suitable for constructing mixed connections of various alloys, such as when joining sheet metal or profiles with die-cast aluminum.
For porous castings and uneven surfaces, in this case, force control also creates flawless material-to-material joints.
Other welding methods hit their capacity limits with lap joints. This is simple to accomplish with FSW technology.
4. What are the engineering applications of friction stir processing?
It may be utilized to make surface and in-situ composites by incorporating reinforced particles into the metal matrix through FSP.
Friction stir processing can increase hardness, wear resistance, ductility, and other properties while preventing flaws caused by material melting.
5 What is the limitation of friction stir welding?
This welding method is frequently slower than other processes. Friction stir welding cannot create weld connections that need metal deposition.
The original cost of the FSW machine is prohibitively expensive. It is less adaptable than hand and arc welding methods.
6. Which materials cannot be friction stir welded?
Dry bearing and non-forgeable materials cannot be fused using a friction welding technique, which requires one of the components to be ductile while heated in order for deformations to occur.
7. What materials can be friction stir weld?
Basically, all materials that can be melted or softened by thermal plastic deformation can be welded with friction stir welding.
And we also have a list of materials that are not suitable for friction stir welding, which is as below:
- Materials without any mechanical properties in their solid phase (e.g., pure metals)
- Structural ceramics that are not porous and do contain oxides (e.g., SiC, A12O3), or totally amorphous ones (e.g. SiC, B4C)
- Polymers (e.g., POM, PA, PP), and high-performance plastics (e.g., PMMA)
- Glasses with a high glass transition temperature (Tg) and no crystallization point
- Materials containing oxides or other inclusions difficult to process by friction stir processing (e.g., TiAl6V4 or AlSi7Mg)
- Nonmetallic inclusions difficult to process by friction stir processing (e.g., CuBe2, Cu2Nb)
Some of the metals that can be friction stir weld include;
- Aluminium
- Magnesium
- Copper and copper alloys
- Hafnium and zirconium
- Inconel and superalloys
- Steel and ferrous alloys
- Titanium
- Dissimilar materials.
8. What is the future of friction stir welding?
Burns, a scientist from the US Air Force Research Laboratory predicts that in 20 years friction stir welding will be more popular than fusion welding.
Friction stir welding has many potential applications that can be developed if its cost decreases and the technology improves in the future.
9. What is the working principle of friction stir welding?
FSW operates by rotating and plunging a non-consumable tool into the interface of two workpieces.
The tool is then pushed through the interface, causing the material to heat and soften due to frictional heat.
The softened substance is then mechanically mixed by the spinning tool to form a solid-state bond.
10. Is friction welding stronger than stick welding?
It depends on the materials being joined. Friction stir welding (FSW) is a process in which two pieces of metal are joined by friction generated by the rotating pin tool.
The tool can penetrate deep into the parent material to form a strong weld that is often stronger than other mechanical joints such as spot or arc welding.
Friction stir welding produces a solid-state weld without melting the parent material and allows uniform filler wire distribution during welding.
11. Why using friction stir welding over other welding process?
This is because of the following advantages:
- It has precision-guided heating and cooling of the heated material. The temperature of the parent material ranges from 800 to 1100°C, depending on the application needs. The thickness of the weld also varies from 2 to 5 mm with FSW.
- The registration of FSW is extremely accurate, which allows for very fine weld thickness control and precise material distribution across diameters, i.e. precision welding.
- The localized heating and cooling of the material makes FSW inherently safe for eye protection since no molten metal is generated or ignited in front of the operator.
- The high mechanical strength of FSW ensures that the parent material is not damaged during welding.
- Friction stir weld joins two different materials simultaneously with uniform filler wire distribution, which is crucial for less-critical assemblies, such as pipe joints and other structural parts of a machine or vehicle.
- Friction stir welding is a very quick and simple process. The time for welding ranges from a few seconds to several minutes, depending on the material and the diameter of the weld seam.
- FSW only generates minimal heat input to the underlying material so that post-weld heat treatments can be performed immediately without causing excessive thermal stress.
- Friction stir welding is possible in all positions while spot welding and traditional arc welding are restricted to specific orientations due to electrical and physical limitations of those processes.
