What is Friction Stir Welding (FSW)?
Friction stir welding is one of the most popular trends in welding technology. The weld is made in the pasty state: it is the solid state of the joining process. The weld is created solely by mechanical deformation by friction.
Technological parameters to be taken into account : the geometry of the tool, the welding parameters (speed of rotation of the tool in revolutions per minute, speed of movement of the tool in mm / min and the angle of inclination of the tool) and the design of the joints.
In 2015, the patent of the TWI falls into the public domain, opening up great development prospects for the FSW technology.
Advantages of FSW technology
Mature technology for assembly of aluminum and copper.
the FSW keeps properties close to the base material
Welding of high-strength aluminum alloys
2000, 6000 and 7000
Welding of dissimilar materials
Al-Cu, Al-Fe, foundry
« Green » process
no surface preparation, no grinding or cleaning is required. No spar, no smoke, no noise.
« Cold » welding
or more precisely pastry state welding. Without melting and no material input.
FSW in 4 steps
Step 1: The parts are clamped either edge to edge (butt welding) or by overlapping (lap welding).
Step 2: The tool, which consists in a shoulder to heat the material by friction and a pin to stir the parts together, is rotated (speed from 400 to 1800 rpm) and then dips vertically into the material.
Step 3: After a temperature stabilization phase (between 1 to 5 seconds), the tool moves along the weld seam (constant speed of 700 to 3000 mm / min depending on the nature and thickness of the components). The heat generated by the friction makes the material softer and the tool stirs the parts together.
Step 4: At the end of the weld, the tool rises vertically leaving a hole. This hole is often seen as a defect; however, many solutions exist to solve this drawback.
FSW welds can be of different types depending on the desired welding configuration and type of material used.
butt welding
T-shape
transparency welding
FSW technology
Advantages of aluminium welding:
- Economic
-
Technological
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Environmental
Cost benefits
Low welding cost: Few consumables (1 tool = welding of 1500-m long),
No material input, no surface preparation, no shielding gas, no gas equipment, low power consumption : 0,2 kWh/m (50% of MIG welding)
Reduction of post-welding inspection
Welding is carried out in a NC machine tool limiting investment
Possible rental of the FSW head to limit the investment.
Product advantages
Welding of all aluminium alloys (1xxx, 2xxx, 4xxx, 5xxx, 6xxx, 7xxx)• Al-Si: easy welding of aluminium foundry, including die casting
High mechanical resistance: weld efficiency of 80-90%, fatigue strength close to the base material
No leakage: water, acid, or air
Excellent thermal and electrical conduction
Forming after welding: stamping or bending of welded parts are possible without cracking
Welding capacity up to 20 mm.
Client advantages
Already democratized in aeronautics, automotive, space, railway and naval sectors
Existing welding standard: ISO 25239
Process advantages
Solution to the shortage of qualified welders.
No surface preparation: no cleaning or grinding is required
The weld is invisible on the back side and requires a small machining on the welding side to remove it if necessary
Replacement of brazing, TIG, MIG or FE welding.
Cold welding (temperature of 400°C): minimal distortion of welded parts, small heat affected zones (HAZ). No spar, no smoke.
Non-toxic: no ozone production compared to arc welding
Welding possible in all positions: no molten pool.
Large part assembly with high ductility
Joint efficiency: Mechanical reduction according to the type of welding
What are the defects that can be encountered during FSW welding?
The professionals of FSW frequently encounter the following defects in their welding :
-Lack of penetration at the root of the weld
-Hooking (typical defect of transparency welding)
-Burr on the solder edges (flash)
-Porosity continues along the weld (wormhole)
Flash
Wormhole
Lack of penetration
Hooking
Want to know more about FSW defects ?
Contactez-nous
STIRWELD
Bâtiment ENS, Campus de Ker lann, Avenue Robert Schuman, 35170 Bruz FRANCE
Stirweld aims to democratize the FSW by:
–The drastic reduction of the investment cost
–A catalogue of quality and low cost FSW tools
–Support of our experts throughout your industrialization cycle
Since 1995, FSW remains a technology reserved for high added value applications involving expensive equipment.
Stirweld invention uses a NC machine tool for FSW: this innovation drastically reduces the investment cost to FSW while offering performances identical to a special FSW machine.
Stirweld innovation allows companies to optimize their machine fleet and to diversify their technology offer to customers.
Our experts assist you in the implementation of the welding parameters, the design of the clamping jig, the choice of FSW tools and the qualification of your applications. In FSW or FSSW, our experts will guide you towards the success of your innovative welding projects.
Prototyping Tests
To identify the optimum FSW parameters
Qualification Tests (NDT) of pieces
According to ISO 25239 standards (traction, fatigue, corrosion, leak)
Post-FSW Operations Test
Surface treatment (OAS or OAC anodizing, nickel plating,
painting), heat treatment, finishing, machining
Non Destructive Testing (NDT)
Liquid penetrant (LPI), X-ray, Ultrasound (US).
Quality documents
D-MOS and Q-MOS (WPS) according to ISO 25239 standards
Leading you to the success of your FSW project
Our specialist team supports you in the implementation of FSW in your company.
The optimization of FSW parameters results in a perfect and reproducible welding operation.
The clamping of parts has a significant impact on your production rate and the weld quality.
We support you in the adjustment of the welding parameters and in the design of your clamping jigs.
