Re: Questions about chipbreaking inserts.

Terry & Kim,

I think it is on topic. Chip breaking is very relevant to automatic
machining, without chip breaking you can't effectively machine
automatically as Kim is finding out.

The problem as I see it is not enough HP, too light a feed and depth
of cut. When I run into a problem of non-chip breaking I up the
feed and depth of cut. .020" depth of cut is awfully small to
expect chip breaking.

The insert style, triangle, is okay, but for heavy cuts I think an
eighty degree diamond may be better. Besides being a more rigid
insert the diamond can both turn and face. The triangle is limited
to turning or facing, but not both with the same setting.

Doug



--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Terry Owens"
<wotisname@l...> wrote:

> Hi,
>
> This is really a machining problem and as such has no place on

this list. I

> have been machining stainless steel for a few weeks with the same

problems

> if you want to email me offlist.
>
> Regards,
>
> Terry
>
>
> > We are running chip breaking inserts on our CNC retrofit lathe.

(13x40,

> > 2 HP)
> >
> > We've got a little problem with swarf buildup, actually a big

problem.

> > When we machine a part of considerable size, removing a

significant

> > amount of material, the swarf will build up around the chuck,

choke the

> > coolant flow to the tool, etc. We often can't run a complete

program in

> > one go without having to periodically stop and clean things

out. This

> > becomes a big pain.
> >
> > Details: we are running TCMT321 (7 degree rake) inserts. This

weekend

> > we were machining 3" diameter 4140 steel parts. Total volume of
> > material removed was about 6 inches^3. We were turning at 750

RPM,

> > feeding a nominal F6 on a 20 thou cut. By nominal, I mean that

someone

> > might have been running a 50 to 300% feedrate override. Our

tool height

> > is set almost exactly at center height.
> >
> > The "chips" we were getting off are really 6" to 18" long swarf
> > stringers. We have machined steel and gotten actual chips off,

but I

> > can't remember exactly when or under what conditions.
> >
> > Questions:
> >
> > a) what sort of chip breaking performance should we be seeing ?
> >
> > b) would the lack of chip breaking performance have anything to

do with

> > running a relatively small insert (ie 321) for the depth of cut ?
> >
> > c) how does one prevent a massive buildup of swarf in and around

the

> > chuck and tooling ?
> >
> > Thanks in advance,
> >
> > Kim