Kristian Ukkonen wrote in
:


D Murphy wrote:
Kristian Ukkonen wrote in
D Murphy wrote:
I guess he found some ultra rare CNMG-411-FS inserts. I wonder if
they are the unobtanium grade.
The exact type under green plastic package is:
"CNMG120408-FS NX2525
CNMG432FS"

On top of package there are listed cutting speeds
for stainless (70-150 m/min) and steel (210-300 m/min).
So these are obviously meant for steel also.
Your depth of cut is way too small for such a large nose radius. You
should leave a minimum of .054mm (2/3)DOC for that radius. Better yet
would be to use a CNMG 431 or 430 insert for finishing.

What is "a minimum of .054mm (2/3)DOC" ???
Where does that come from?

Actually, that is the rule of thumb for turning. For boring your DOC
should be as large or larger than your nose radius. In your case the bar
is not deflecting downward, it is deflecting away from the cut. You
either need to increase the DOC or decrease the radius. Decreasing the
radius would result in lower cutting forces and would be less likely to
chatter.


The specs of FS breaker state minimum DoC of 0.2mm..
That is in catalog of Mitsubishi Carbide for this insert,
and in webpages documents of MC as well.. Like:
http://www.mitsubishicarbide.com/EU/...01/pdf/lj395e_
dimple_bar.pdf That small DoC was why I selected the -FS in the first
place..

My normal (working fine) CNMG inserts have a nose radius
of 0.8mm as well.. They "work" with 0.1mm DoC except the
surface finish is not so good - but no chatter..

Read this:

http://www.manufacturingcenter.com/o...ok/chap_10.pdf


--

Dan