"Martin H. Eastburn" wrote in message
...
Harold and Susan Vordos wrote:

"Martin H. Eastburn" wrote in message
t...

I think we need to think about this a little.

Diamond cutting tools are steel based and cut steel HSS and carbide
drills and mills. Perhaps there is transference, but not all that
much ?

Martin


They may do that, but are they recommended for the application? Dunno.
I've never used diamond turning or milling tools. If so, do they
recommend
specific speeds, to keep the temperature down? That's the critical
point.

I'm not convinced I'm the right person to answer the degree of transfer,
but
for diamonds that rely on sharp corners to do their work, it takes very
little to change them appreciably. Iron has an affinity for carbon,
and it
isn't proud where it gets it. Up to the point of saturation, so long
as
the temperature permits transfer, it will absorb it. That tells me
that
prolonged contact at high temperature, iron could literally absorb a
complete diamond.

It's not a heat thing alone, nor is it an iron thing. Diamonds will
withstand soldering (re-tipping prongs, for example) with no ill
affects,
and they can withstand a constant dressing of aluminum oxide or silicon
carbide wheels, even large ones such as are found on centerless
grinders.
They are often 24" in diameter and 8" or more wide. Heat isn't a
problem,
but combined with iron, it quickly becomes one. That's about the
extent of
what I know, and from experience, I know that contacting diamond wheels
with
iron (steel) is a mistake. The typical diamond wheel feels as if it's
been
greased once steel has been applied. Sorry I'm not more help.

Harold


Diamond is typically grinding and sawing. Sapphire is and Diamond I
believe used
in exotic sharp edge cutting of plastics and glass. Typically both
fracture
under load if not supported.

Since the diamond is best in conduction - your hand on the far side of a
thin diamond
window would feel almost all of the heat on the other side - so when the
tool tip gets hot,
it conducts to the base metal - steel and flows off - cooling the diamond.

Continuous heat addition (at one spot ) (as with a flame or arc) would,
but a turning
tool and the conduction prevents this. Also the typical use involves a
flood of water
based coolant.

Martin

I'm not sure what you're saying here, Martin, but diamond turning and
milling cutters are not used on ferrous metals except in very rare
situations. They just don't last, for the reasons Howard has explained.

In production, diamond is use primarily on high-silicon aluminum. Other uses
include composites, plastics, glass, and other non-ferrous metals.

The development that made polycrystalline synthetic diamond a near-necessity
in production was the use of very high-silicon (hypereutectic) aluminum
casting alloys in automotive applications. Another one of the early users
was Mercury Marine, who used it for machining their hypereutectic outboard
motor blocks. OMC soon followed suit.

--
Ed Huntress