"Martin H. Eastburn" wrote in message
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Saw blades have diamond pressed into slots on the circumference. These
slice through rock and cements...
I have sliced through tons of material. The diamond doesn't absorb into
the host material (the tool)
but I suspect the very highest temps are only at the tip where atoms are
stolen.

The host material isn't where the diamonds are mounted. There's usually an
alloy that becomes the bonding agent, and it doesn't have an affinity for
carbon. There is no transfer of carbon for that reason.


Is it simply a matter of cost ? - the carbon is absorbed a little and the
tool becomes used up?

With grinding wheels that are dressed by diamond, the diamond gets dull and
ceases to cut easily with prolonged use. If you're familiar with dressing
grinding wheels, you understand why the typical diamond dressing tool mounts
the diamond at an angle instead of at right angles. That way, all you have
to do is rotate the diamond slightly to present a sharp corner of the
diamond to the wheel so it cuts cleanly instead of burnishing the wheel.
It would be much the same with diamond grinding wheels. The slightest
dulling by absorption renders the diamond far less affective. The diamond
may not be used up, but it gets dulled to the point where it takes
considerable pressure to get it to cut, and you risk tearing the diamond out
of the matrix as a result.

Maybe the data is simply old economics. Diamond drill heads bore through
iron cobalt deposits and
other iron rich layers for many years in well drilling. So maybe research
needs to look at this
again with a different point of view.

Martin

Martin, I think you're overlooking the fact that well drilling takes place
at much lower speed, so low that the critical temperatures are never
approached.

I'm not convinced anyone is suggesting diamond can't be used for cutting
ferrous metals, but there are inherent hazards involved, one of which is the
shortened life of the tool, especially if it's at accelerated speeds. The
lesson that's important for the home shop types to learn is that diamond
grinding wheels should never make contact with iron or iron alloys at high
speeds in order to preserve the diamond. The slightest contact affects a
wheels ability to cut. So much so that the wheel often requires a dressing
in order to restore a wheels ability to cut freely. I'm sure wheel loading
is a part of the reason, but dressing the wheel takes life out of it, so
it's a good idea to minimize dressing. You can do that by avoiding grinding
steel.

Harold