Re: [CAD_CAM_EDM_DRO] Re: Questions about chipbreaking inserts.

Last comment on this "off topic":

I think the lack of chipbreaking has something to do with the Z axis
feedrate relative to the X axis cutting depth.

I just ran a cut of 0.050 at various Z axis feedrates. At 2 or 3 IPM, I
get chip action. If I crank up the feedrate to 4 or 6 IPM, I get
spirals.

For whatever reason, we've been taking light cuts at relatively high Z
axis feedrates. I think we can get chip action by increasing the cut
depth to 50, 60, 100 thou and decreasing the Z axis feedrates
correspondingly.

Our lathe isn't low on power, ie we can take much deeper cuts. For
whatever reason, we've been taking light cuts at high speed. Now that I
know this affects the chip breaking, we'll change our ways.

Thanks for the tip and please excuse this (last) off topic post.

Kim

On Tue, 2003-09-30 at 10:21, doug98105 wrote:
> 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
>
>
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