View Full Version : ceramic insert breakage

10-19-2005, 01:09 PM
We have a kabootle of broken ceramic inserts - I recall seeing a link to a web site that shows typical broken inserts and probable causes. However, I cannot seem to locate it again. This is costing us a fortune.

Can anyone help?



Forrest Addy
10-19-2005, 01:46 PM
Them things are brittle. There's several failure modes for ceramic inserts. Thermal shock when the coolant hits them when still hot fresh out of the cut, chip snarls, crossing center in a facing cut, interrupted cuts, sometimes even a closed inclusion on the surface of hot rolled will result in a series of baffling ceramic insert failures.

Try starting the tool on a champher.

Personally I love ceramic inserts. I've been using Kyrocera inserts for years now and while they are a bit brittle they sure eat up HT 4140 dry cutting at 800 - 1000 FPM and 0.011" feed. Going that fast seems to have a HP multiplying effect. I can remove more stock per HP for some reason.

Reliable ceramic tooling is the main reason I doubled my lathe's HP. The net result is the same forces on the tool and spindle at double the RPM and HP. The neighbor kids peek in the shop door when I'm running my lathe hard - they've learned to listen for the sound. I won't allow them in the shop when I'm working but they like to watch the sparks fly.

10-19-2005, 06:14 PM
Hi Axel,

Can you give us some more information about your application and usage? Inserts don't like any kind of shock, either mechanical or thermal. If you're doing an interrupted cut, like facing over a recess, or trying to face an uneven surface, you may have problems.

Leigh W3NLB

10-19-2005, 06:40 PM
And if you find the website, please let us know what it is. rock-

10-20-2005, 04:43 AM
As they say, "I knowed I'd find it. It was in teh last place I looked".

Please see:

http://www.kennametal.com/images/pdf/US/Sections/KMTL-Lathe_Tooling_Catalog_4010/KMTL-4010-inserts_tech_data.pdf;jsessionid=ZD3QL4NTAL05ZLAUB IOCFEVMCQFB0IV0