Friction stir welding
Reading the latest Popular Mechanics (May 2010), they mentioned something I have not heard of before called friction stir welding. It's a process used to join metal, usually aluminum, without an arc. Instead, it uses a spinning rod, rotating at 15,000 rpm to heat the metal and high pressure to join the heated pieces together. It can move at 8 inches per minute and weld 1 inch thick plates in one pass instead of a dozen or so using conventional techniques.
It's only used on large welding jobs at the moment because of the equipment necessary, it won't be replacing your MIG welder anytime soon, but developments are coming which will allow it to join steel or different metals and a tool called a bobbin may allow quicker and smaller jobs. It's currently used in the space program and in similar situations, knowing some of the visitors here, I bet a few of you are familiar with this technology already. Very cool.
Link: Wikipedia
{ 28 comments… read them below or add one }
I’m tempted to experiment with this on the CNC.. Joining dissimilar metals.
This looks like a new “spin” on friction welding, used to join a lot of axle tubes to brake plates. The machine is basically a lathe with a brake and no filler metal is used.
I’ve seen this before and I think it’s fascinating. It’s like rubbing two sticks together to make fire. All you really need is heat. It also produces no arc flash, probably uses less electricity, and has nearly zero consumables. I’d bet it’s noisy as hell, though, and you coudn’t use this technology on the home level…not yet.
I heard that they were going to do spot welds using this technology in the aerospace field.
Imagine the reduction in drag on wings if this process replaced rivets.
Heard of this already? Nothing much new here , I am 53 yrs old and this basic technology was taught when I was in college ,Nortly is correct it is the same process he described.
That’s the method they used to build the Eclipse verylight jetplane. no rivets and such.
I have actually replicated this process to weld a carbide tool to a billet of 7075 aluminum during an aggressive plunge roughing sequence. The key is high RPM and plunge rate with a failed coolant pump.
One process I always found fascinating was ultrasonic metal welding. Basically the pieces are vibrated together under localized pressure and fuse together as one. You can’t even tell it’s happening.
-todd
The noise level is less than arc welding unless you use Jeff’s technique LMAO! Been there done that!
’1 inch think’ …….Who edits these entries???
@Hawkeye : “‘1 inch think’ …….Who edits these entries???”
Fixed, … I edit my own entries, and I’m usually pretty careful, don’t you thick?
The levity today is much appreciated.
I learned about this at work. This form of welding can produce very aesthetically pleasing welds if done properly. This process is used and actively being developed in the aerospace industry for making one-piece assemblies to reduce weight and part complexity.
The results is truly one piece they could be no more closely bonded if it was a cast or forged as one.
I’m an NDT technician for United Launch Alliance. FSW is currently used to join the skin panels (total of five) on the Delta II and Delta IV fuel tanks. The resulting weld seam is roughly an inch wide, and the material used is 2219 AL .380 inches thick.
The welding “bit” rotates at only 1800 rpm for most of our applications, but the pressures required to plunge and drive the bit can exceed 20 tons per square inch, so I was told. Currently, spot welding is impossible as the extraction of the tooling leaves a hole, and attempts with breakoff bit designs have so far failed.
My expertise lies primarily in the followup inspection using phased array ultrasonics. In 9 years of inspection experience, we have never failed a friction stir weld. However, due to the pressures associated with the machine, we rarely complete a tank without a breakage.
The machine itself is four-floors tall, and our weld lengths run from 18″ for a pre-process test panel all the way up to 600″, depending on build requirements.
Wired magazine gave this a write up a few issues back discussing the aerospace applications. They had a pic of the 4-floor tall machine at work.
I remember watching some discovery Channel documentary on the Airbus A380 and I think this is what they use to put together the wing panels for the super jumbo.
Ford MoCo has been doing this for years to weld their mouting plates for hubs to the end of their axles. Spin the axle shaft press into their hub plate and presto 1 unit. Made balancing it easier too.
Christopher, has the company tried using very short individual bits for spot welds? Calculate the length so that at the completion of the spot weld, the bit is just proud of the surface, to be un-chucked and machined flush later.
@ Micah:
You have nothing to worry about with rivets. The aerospace field has been microshaving countersunk rivets flush c/t the aircraft’s skin for quite a while now.
If I’m not mistaken I believe Mazda uses friction stir welding to join dissimilar metals on the current MX-5. To reduce weight, they are using an aluminium boot (trunk) lid and welding it to galvanised steel parts using FSW.
We work with allot of heatsink and often get material in that is FSW edge to edge because it is wider than can be extruded.usually a 24″ wide by say 4-6″ tall with the base being .750 thick. They use this process in the manufacture of nuclear submarine screws or propellers if you like. That material is similer to aluminum nickle bronze if I’m not mistaken.I believe the technology was deveoped by Rockwell,again if I’m not mistaken.
It looks like TWI of Cambridge UK filed for world patent in 1991 for this tecchnology.
This is NOT Friction Welding.
FSW does not ever melt metal. Between the pre-heating by the tool’s shoulder and the pressure involved, the material is plastically removed from the leading edge of the tool and deposited in the wake. It’s basically ‘wiping’ the aluminum from the front and leaving it behind.
Jigging and tooling is critical and so only certain applications are possible.
Also, the resulting weld metal has material properties similar to ‘as cast’, so the joint design (and material selection) must take that into account. For example, on the Space Shuttle main tank the plates are made thicker where they will be joined by FSW.
BS WE OSU 2000 (Go Bucks!)
AIUI The important point is that, unlike conventional friction welding, the metal is NOT melted. The stirring process does heat the metal but does not allow it to melt and reform crystals that would weaken the joint.
Bill
We built the FSW machine shown in the photo. for more info on FSW go to mtiwelding.com and click the “friction stir” tab.
The place I work has the largest FSW in the world. They welded two chunks of 2 inch thick aluminum together the other day.
My favorite toy from youth(I’m 46), was the “Spinwelder” It was a plastic gun with a dc motor in it, and you used little white plastic rods that attached to the gun to weld black I-beam shaped plastic pieces together. It was like a plastic erector set, but welded.