6 replies to this topic

[mariner]

Cheapracer, living in China , would probably call this "stir fry"

Not knowing much about production engineering ( among many other gaps) I had heard of rotatary friction welding for half shafts but not Friction Stir Welding.

http://en.wikipedia....on_stir_welding

The Wiki artlcle above seems ( by some cross checking with two SAE papers) to describe it pretty well.


Now I am hopeless at normal welding. I have been to courses and can MIG weld two bits together but I would NEVER trust anything safety critical welded by me. I tack weld then get an expert in. Alloy welding to me is one of those magic skills only TIG artists can do!

I am sure FSW is not a silver bullet but it seems to have many advantages over the MIG/TIG thing - lower temperatures, precise key variable control , less distortion.

I am expect I am over simplifying but it would look like anybody with a vertical mill with power tranverse could set it up to do FSW as long as the two bits being welded can be tilted slightly on the transverse table and the mill can run at 1,600rpm or so.

A German company has made simple three part tool to do FSW spot welds . A stationary circular plate clamps the two parts together and the disc and the pin rotate iand move down nside that. So rev it up, push it down and , bingo, two bits of aluminium spot welded....

Has anybody here used or seen FSW in action?

Edited by mariner, 26 May 2011 - 18:16.

[bigleagueslider]

mariner,

FSW is a solid state joining process, similar to friction welding or diffusion bonding. This means that it joins the metal parts without the material in the weld zone undergoing a phase change (ie. from solid to liquid to solid), as occurs in a conventional fusion weld process. Solid state welding processes can join metal alloys that cannot normally be fusion welded, and the resulting joints have metallurgical properties equal to the base material. Eclipse used it to join stringers to fuselage skins on the Eclipse 500 jet, and Boeing uses FSW to weld Al-Li cryogenic fuel tanks on their Delta IV rocket.

In aerospace, a joint weld zone produced using a solid state process is considered to have metallurgical/fatigue properties as good as wrought material. While a fusion weld joint would have be assumed to have substantially inferior properties (grain boundaries, inclusions, etc.) in the weld zone.

FSW uses a spinning tungsten pin forced into the weld interface between two metal parts to generate a carefully controlled friction heat, which locally heats the metal to a plastic state, but not to a liquid state. The spinning tungsten pin also produces mixing/diffusion of the materials in the weld zone. Controlling the speed and feed rate parameters with FSW is critical. The amount of spindle torque and radial force required for FSW would be difficult to obtain in a vertical mill, since it would be much greater than that required for machining, unless the parts being welded were very thin section. FSW machines have massive spindles and drive motors, and also require very strong and rigid fixtures for holding the parts.

I've never seen FSW in person, but I have seen video of the process. It is truly fascinating to watch a solid tungsten pin pass through solid aluminum plate.

http://wn.com/Friction_Stir_Welding

While FSW can produce very high quality joints in aluminum alloys that could not normally be welded, it is not a process that lends itself to high production rates

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[cheapracer]

Cheapracer, living in China , would probably call this "stir fry"

Stop stirring the pot up.

[Tony Matthews]

Wok?

[Lee Nicolle]

I have seen a few examples of friction welding. Unfortunatly they were not supposed to be! Gears welding themselves to shafts, sleeves and the like. Though largely solved these days with modern oils.

[Catalina Park]

There is some very good videos on youtube (sorry Cheapy) with friction stir welding.

[Greg Locock]

There is some very good videos on youtube (sorry Cheapy) with friction stir welding.

I hope you don't read your mum's emails on that screen.