"Ignoramus16724" wrote in message
...
On 2009-06-27, Ed Huntress wrote:
Where cutting forces or non-cutting friction is high, you can add sulfur
to
oil and you get more film strength, with little influence on lubrication,
without increasing the puncture threshold. Tough cutting conditions, such
as
tapping, benefit from the sulfur. You can also add chlorine or a variety
of
other chemicals to get a somewhat mysterious reduction in shear strength
at
the cutting edge. Somehow they get right into the shear area and reduce
cutting forces. This was the subject of a lot of research during the
'50s.
Maybe they have it figured out now. They didn't when I was writing about
it,
in the '70s and early '80s. The extreme example of this was carbon
tetrachloride, which produced a very large reduction in shear strength
right
at the cutting edge. Don't use it.

Ed, can you elaborate on your "do not use them" statement.

I should have made clear that I was saying not to use carbon tetrachloride.
I don't want to be sued when somebody's liver and kidneys collapse. d8-)

Chlorine has been taken out of many cutting fluids, too. Sulfur is still
common in the thick formulas used for thread-cutting of pipe, and you can
still get sulfated cutting oil for turning and milling, too.

I have old
"GALAXY thread cutting oil" with sulphur and chlorine base. It seems
to work well. Is it harmful to health?

I don't know. There are cautions that you'll see particularly regarding
chlorine. How serious it is, I don't know.

But I'm hardly the one to ask. When I need a chemical for cleaning, cutting,
or whatever, I go for the one with the skull and crossbones on the label. It
usually works the best.

--
Ed Huntress