"Jim Wilkins" wrote in message
...
On Jun 27, 5:08 pm, "Ed Huntress" wrote:
"Joseph Gwinn" wrote in message
...

When you get into really high-speed cutting, Joe, they often run dry -- or
with a 1/2-liter per 24 hour lean oil (vegetable) mist.
--
Ed Huntress

The Cincinnatti Milling Machine book that Lindsay used to sell (and I
can't find) contained reports on extensive cutting experiments that
seem to be the origin of accepted practice. IIRC their results were
considerably less definitive than the rules that developed, for
instance they found little difference between oiled and dry on cast
iron, and suggested dry mainly to minimize the mess. I've based my
practice of using a minimum of brushed-on oil on their results,
considering that I make one-off parts and can easily regrind a drill
or lathe bit afterwards.

jsw

================================================== ==

Cincinnati Milling sponsored some of the university research and was a great
source of data at one time.

The real high-speed stuff, machining dry with advanced cutting tools, is
something that's developed over the past ten or fifteen years or so in real
high-volume production. It came in with the widespread use of CBN,
multi-layered coated carbide, and to a lesser extent, with diamond coatings.

Those multi-layer coatings can't stand any thermal shock, but they can
tolerate very high temperatures.

Some coatings flat out won't do their job if you run them with coolant. Any
of the multi-layer inserts that have a moly disulfide coating, or one or two
others, are made to "polish" the top of the insert from running dry with a
lot of friction. Then the soft coating disappears, and the hard layers
(titanium nitride, various carbo-nitrides, etc.) run best dry and hot.

The thick aluminum oxide coatings in those multi-layer tools are intended to
insulate, first by sublimating and imposing a thin gas layer between the
chip and the tool, and second just from their bulk insulating property. They
don't run right if you run them with coolant.

--
Ed Huntress