Re: Those Cheap Diamond Inserts

Bob La Londe <none@none.com99> writes:

On 7/29/2024 11:38 PM, Richard Smith wrote:

I heard diamond
* works for Ali because it has no solubility for Carbon
* does not work for irons/steels because the hard tool "disappears" by
   solution into the iron
?

>
My apologies.  I didn't at all mean something like a PVD diamond
coating.  DCMT is a diamond shaped insert.  Typically your find them
coated with TiN, uncoated, and occasionally with TiAlN or AlTiN
coatings.  My point was these small geometry inserts that work so well
in under power under-rigid machines like the typical import 7-8 by
10-16 mini lathe also work on a heavier machine.  If the big boy
inserts don't work these still do.  In this case I was cutting 304
stainless steel. It improved the finish, didn't require sharpening,
had less heat input, and did the job much faster net elapsed time.
>
FYI:  I do a fair amount of aluminum cutting, and generally I've found
bright sharp uncoated tools do the best job and have the best material
removal rate for me and leave a good finish.  Diamond was popular when
I first started cutting aluminum on machine tools, and more recently
ZrN has become the popular coating.  I've tried them and the simple
fact is a coated tool isn't as sharp.  They might work better for
larger tools on larger machines, but on middle weight machines with
limited horsepower (5 or less) a bright sharp uncoated tool works best
for me. For high speed flood coolant makes the tool last without chip
welding, but coatings do not.  On smaller tools horsepower isn't even
a factor as the tool can't take it anyway.
>
>
--
Bob La Londe
CNC Molds N Stuff

Thx for this detail.
Interesting yes certainly.
Sorry "got the wrong end of the stick".

I used cutting insert tooling - aagh - 30 years ago.
Vertical milling shell-cutter on steel.
Did well - they'd never seen steel chip ejection like a chain-saw
cutting timber.  Took a visit from the rep. who explained this is how
the tooling is supposed to be used :-)
Coated carbide inserts - coating the gold coloured one - a Ti nitride(?)
coating - for this steel.