| Look at the Eclipse aviation website. They were pushing this process 4
| or more years ago at the Oshkosh airshow.. Was real interesting watching
| a mill with a special stir welding bit "weld" two sheets of aluminum
| together. They had xray sheets showing no voids etc. to validate the
| process. At the end of each demo they would warn all us homebuilders
| "Don't try this at home."
| I guess they're using 3 axis cnc robots with the special tooling to do
| the welds on all the sheet metal joints on their aircraft. Gonna be
| interesting in 10 years after(If?) they hit mass production to see how
| well it all holds up.
| New processes haven't been to warmly accepted in the aircraft industry.
| Just look at the Grumman Tiger with it's bonded aluminum wing surfaces
| and see how much bad press they are given for them. I really don't know
| if it's well deserved.
Boeing's got a pretty penny invested in it, and is using it on their
spacecraft. I've seen some demo stuff, which is amazing! Very expensive
setup, though. Obviously special applications where weld quality is
critical. There is a small ridge on both sides of the weld which has to be
removed. For the most exotic alloys no special filler rod is required, but
you have to back up the other side of the weld from the extreme pressure,
and obviously it being a heat sink it has to be carefully designed for the
I didn't realize it at first, but there has to be a tab at the beginning
and end of the weld where the probe (?) passes through. There is the probe
or whatever inside the weld, spinning on through and pushing the metal
around behind it, and a flat part above it to keep the pressure up and not
allow the metal to flow up and out.
I've used that process a number of times trying to drill titanium sheet
with a regular drill bit, although it's far from my preferred process. Just
press hard, go fast and let the bit burn its way through! Of course the
hole isn't precision or pretty, but the engineers say it's okay. Nothing a
reamer won't clean up anyway.