Re: Carbide insert information

Kevin,

I don't remember if you mentioned whether you were looking for
turning or milling inserts

There's a lot going on in turning inserts these days. A few
manufacturers are coming out with "high positive" inserts. I assume
this is because newer carbide formulations allow the use of more
fragile sharp cutting edges instead of the old blunt brute-force type
negative rake inserts which required lots of horsepower to do the
job. Also, probably because there are so many small high speed CNC's
being made there's a need for low hp type inserts. I've had good
luck with high positive rake inserts from HB Rouse, 1-800-943-4426.

For turning, mostly I use the CCMT style. That's an 80 degree
diamond so the same insert can face and turn. It sits in a level
pocket in the holder. With the same holder everything from negative
to high positive rakes can be used so one holder can handle a number
of turning situations.

There's just as much going on with milling inserts. I've noticed the
newer milling inserts are mostly positive rake, but they need to have
a slight dulling radius on the cutting edge to hold up in a milling
situation since milling is a series of interrupted cuts where turning
usually is a continuous uninterrupted cut. In my experience, even
with the positive geometry, milling inserts need a fair amount more
rigidity in the machine and more hp than plain old end mills.

Doug


--- In CAD_CAM_EDM_DRO@egroups.com, "Kevin P. Martin" <kpmartin@t...>
wrote:
(snip)

> None of the catalogues explain the rake issue very well... The

negative rake

> tooling seems to combine flat-topped inserts with tool holders that

hold the

> insert tilted by the desired rake angle, but the positive rake

tooling seems

> (but I can't tell for sure) to use an insert with a raked top

(combined with

> chipbreaker), held in a level land in the tool holder. It should

also be

> possible (and seems to be representable in the coding alphabet

soup) to take a

> high-relief-angle insert with a flat top, and hold it on a positive-

rake land in

> a tool holder, sacrificing some of the relief angle to get positive

rake, but I

> have seen no such tooling system. Perhaps some other issue

precludes this

> configuration.
> -Kevin Martin