Friction stir welding:
The friction stir welding process is a solid state welding. The lower heat required to provide weld which result in lower post weld distortion. The FSW process low temperature during the welding as compared to other welding and eliminate the solidification defect.
friction stir welding tool in machining:
Friction stir welding joining the material use of non – consumable rotating tools. Which tool is comprised with two main components. They are shoulder and pin as shown in figure. The tool is plunged at start of start of joint up to end of work piece depth. The shoulder contact to work piece and compressed together, contain the plasticized weld region.
The work piece heated by combination of friction and adiabatic heating, plasticizing the metal. The plasticized material rotated around the tool and consolidated due to compression force from the tool. the friction provide between rotating shoulder and the surface of work piece, so heat generated on surface. The thin sheet metal will be welded.
The work piece thickness increases. The more heat generated by between work piece and rotation pin. The pin is mainly used for ensure sufficient working of material at weld line and control the flow of material. The pin profile such as flat or re-entrant fluted.
The rotational pin has odd number of equal space flat to maintain maximum cross sectional for opposite to any re- entrant features. The pin is continuous rotated and then transverse along with the weld joint depth. After complete transverse with desired length, the tool is retracted.
The friction stir welding is used for welding of aluminum alloy high melon temperature metal such as nickel alloy, titanium and steel. It welding process can be welded to almost any geometric configuration including fillet, lap, butt, and T-joints. Currently the single pass welded on aluminum alloy up to 75 mm thickness, titanium up to 25 mm thickness and steel up to 19 mm thick.
- It suitable for automation process.
- Provide very strong bond between the weld materials.
- Solidification gas porosity and cracking defects caused by absorption of hydrogen during welding not occur.
- Small heat affected zone compare than conventional fusion welding.
- Not require highly skilled operator.
- The different length of work piece weld together require different length tools.
- A keyhole is provided on left end where welding tool removed
- The work piece is clamped. If the deposition of metal is required, it is not good.
The main friction stir welding applications:
- Automotive product of aerospace application in automation.
- Automotive marine application