"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 ?

The cutting part of diamond tools is diamond (natural industrial diamond or
vapor-deposited diamond coatings, or, in a couple of rare cases,
vapor-deposited diamond stripped from a substrate and diced into thin
braze-in tips), or diamond bonded in a press-and-sinter operation with one
of several binders (PCD tips). There is no steel involved in the actual
cutting tip.

As someone said, diamond combines chemically with steel or iron much quicker
at high temperatures. It's a very expensive way to carburize a piece of
steel. g

It works Ok for cool lapping, badly for turning or milling, and it's a big
loser in grinding. Still, it has its uses for cutting ferrous metals. You
just have to be aware that you're in for an expensive proposition because of
the chemical action.

A couple of years ago I talked to a scientist at GE materials and I was
surprised to hear him say that cubic boron nitride (CBN, or PCBN) also
combines with steel at high temperatures, but at a much slower rate than
diamond. Chemistry is one of my weak areas so I can't comment but to pass on
what I read or hear.

Anyway, CBN lives as a tool material because of the problem of diamond
combining with ferrous metals in common metalcutting operations, simply
adding to the carbon content of the metal being cut.

--
Ed Huntress