From: dingbat@codesmth.demon.co.uk (Andy Dingley)
Newsgroups: rec.autos.4x4
Subject: Re: Grand Cherokee vs Range Rover
Date: Thu, 18 Apr 1996 15:08:31 GMT

The moving finger of dstock@hpqmdla.sqf.hp.com (David Stockton) having
written:

>the rear radius arms [...] are fabrications of steel tube.

They're quite an interesting fabrication. The centre is steel tube,
with forged ends. They're joined, not by stick welding, but by
rotational friction welding. One piece is rotated in a machine like a
lathe and then brought to bear firmly against the other. The friction
between the rotating and non-rotating components causes their surface
to heat up to welding temperature and the pressure forms a weld. You
can tell by looking at the outside - there's a characteristic double
ring of welding flash around the joint, where excess metal is squeezed
out sideways.

--
Andy Dingley                          dingbat@codesmth.demon.co.uk

"Cut the second act and the child's throat"
  - Noel Coward, on seeing the young Bonnie Langford on stage

Newsgroups: rec.autos.4x4
From: dstock@hpqmdla.sqf.hp.com (David Stockton)
Subject: Re: Grand Cherokee vs Range Rover
Date: Fri, 19 Apr 1996 07:39:14 GMT

Andy Dingley (dingbat@codesmth.demon.co.uk) wrote:


: to heat up to welding temperature and the pressure forms a weld. You
: can tell by looking at the outside - there's a characteristic double
: ring of welding flash around the joint, where excess metal is squeezed
: out sideways.



     It's an excellent process, the joint temperature goes no higher than
really necessary so the effect on the metallurgy is minimised, and the
material ejected from the weld zone carries away any surface
contamination that had been on the faces to be mated, without allowing it
to diffuse into the melt in the weld zone.

    As Andy says, you just spin two things and ram them together and wait
for them to stick together. The Welding Institute used to do some rather
good videos of various processes, and I remember seeing the one of this
some time ago..


    This is one of the things I like about Land-Rovers, care to make
parts where failure modes are bending not snapping so that after "a big
one" you can drive on....  your geometry may have shifted to something
that Euclid probably never thought of, but things are still attached..


  Cheers
         David