History channel: cnc MIG

--Saw a show on History Channel about building aircraft carriers and
they had a nice bit about the history of cnc MIG welding. What I don't get
is why the long, continuous welds they are capable of doing doesn't induce
warping of the joined components. What am I missing? They were talking about
a 500 amp MIG gun...

--
"Steamboat Ed" Haas : A steaming pile of
Hacking the Trailing Edge! : obscure information...
www.nmpproducts.com
---Decks a-wash in a sea of words---
.