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Evan
12-22-2003, 09:37 PM
Friction Stir Welding

Just ran into this today. Interesting process. It can weld aluminum alloys previously classed as unweldable.

http://www.twi.co.uk/j32k/unprotected/band_1/fswintro.html

yf
12-22-2003, 09:48 PM
Seems like it is similar to the "Cold welding process".

I have actually used a cold welder to join copper wire end to end.
It is used in wire drawing operations when one spool empties, the next piece of wire is welded on.

It can best be described as 2 blocks (Dies) with a hole in each that is a slip fit over the wire, that have a cam type grip inside. These 2 blocks are then forced against each other by the compound leverage mechanism.
The wire sort of mashes together end to end and makes a joint that is undiscernable after dressing down and drawing. There is no noticeable heat produced at all.

Cass
12-23-2003, 12:05 AM
Stir welding is a production process at most of the airplane plants such as Boeing and Lockheed. Special machines for doing curved surfaces etc. I have read several articles on the process but have never seen it in use. Seems to have gone from annoucement to production use a lot faster than some other developments.

Thrud
12-23-2003, 12:20 AM
Evan
The A320 Super plane will have a spar that is joined using this process - I have mentioned this before. This is old technology, has been out for about 6 years now. It is nearly the same process as milling ecept high pressure is used to hold two pieces together while a high horsepower head turns an alloy shank at high speed through the seam of the two pieces. The seam is stronger that the parent metals.

It is certainly a neat process.

BC21OSH
12-23-2003, 12:35 AM
Eclipse Aviation has had their display out out the EAA Airventure for the past two years. They use friction stir welding in their construction, however their plane is not yet commercial. They intend to provide a jet for less than $1 m. They display parts of the aircraft as well as complete planes at Airventure. The FSW is a really clean bonding process compared to rivots.

http://www.twi.co.uk/j32k/unprotected/band_1/c1221.html


Bernard


[This message has been edited by BC21OSH (edited 12-22-2003).]

BC21OSH
12-23-2003, 12:37 AM
Oops,

Double Post

Bernard

[This message has been edited by BC21OSH (edited 12-22-2003).]

ibewgypsie
12-23-2003, 07:25 AM
Just another version of the old blacksmiths hammer weld.. rotating force instead of hammer, friction instead of forge. Is it as good or versatile as a "normal" welding process? Probably not.. Is it better then inhaling Flux off the rods, probably..

Neato tho.

David

wierdscience
12-23-2003, 10:35 AM
Yep,I saw one on action about five years ago down at Stennis space center,neat machine and neat process,but given my experience with other forms of friction welding I don't trust it.

[This message has been edited by wierdscience (edited 12-23-2003).]

metal mite
12-23-2003, 12:37 PM
I don't trust it either.
I frequently have to machine little friction welded bars made of titanium, or 304 ss welded to aluminum.
Have to save both cutoffs from each end and number them with the good part.
I always machine them very gingerly cause i don't want them to break on my watch.
They are used for checkvalves or something.
mite

crypto
12-23-2003, 11:56 PM
Many, many years ago I fooled around with friction welding on the lathe. But it was merely 3/8" bar steel against a similar bar. Never occured to any of us to try welding steel bar to aluminum or some other dissimilar metal. I've got to try this.

As I recall we merely held one of the bars in the Jacobs Chuck in the lathe and just jammed it up against the spinning bar in the lathe chuck until there was a very sudden rise of heat and color and then suddenly the loosely held bar in the tailsock Jacobs would start to rotate as the weld was formed. Very fast process it did not take much to do.

Don't remember why I had to do it. I believe some naval engineering project was looking into it. Just remembered we used a Monarch EE for the project and when the bars were welded together they would sometimes stop the lathe.

Rich Carlstedt
12-24-2003, 02:09 AM
Seems to me some of the machinists at work did this occasionally when the drill bit would stall and they kept power on the drill...never could find that guy, he just left blue jaws and burrs !

Thrud
12-24-2003, 03:27 AM
Oscar

That particular form of welding is called "upset inertial" welding it still is used to mount turbo charger shafts to the impellers. But you use more sophisicated machinery to do it so the parts are not marred in the process.

The this stirring of the metal produces a seam that is stronger than the parent metal because it is more homgeneous than that of the parent metal. I do not know about dissimilar metals, only Identical alloys joined together.

Evan
12-24-2003, 03:49 AM
Thrud,

Apparently it can be used to join dissimilar metals. In particular, magnesium to aluminum with no danger of ignition since the metals are never molten. It is used to make racing wheels with magnesium spokes and aluminum rims. The process can be used, so far, to join materials up to 70mm thick, over two inches.

BFHAMR
12-24-2003, 05:14 AM
One of the Tech colleges in the area had a nice example of friction welding.... a dead center permanently fixed to a piece of cold rolled. The instructor kept this piece as an example of what not to do.

Dan

wierdscience
12-24-2003, 10:19 PM
If you look in the Thomas register there are quite a few companies that list that capability as well as the equipment,I think its listed under friction welding or upset welding.