Tantung parting tool question.

[websterz]

I make lots and lots of interrupted parting cuts in annealed 4140, mostly in 1/2" and 9/16" material. Recently I purchased a couple of 3/32" Tantung parting tools and I am wondering about the speed and feed. I have no experience with this tooling and need a little guidance. My lathe is a Grizzly 12x36 so top speed is 1400 rpm.

[Harold_V]

I can't provide specifics, but TanTung should be capable of tolerating higher temperatures than HSS--so you should be able to run faster, but not as fast as carbide. I'd suggest stepping up in increments, observing how the tool behaves. Might have to sharpen once, to repair a burned tip, but from there you'll have a good sense of its capability.

Many years ago I had a parting tool ground from a Stellite blank. Amazing how much speed it would tolerate without problems.

Harold

[websterz]

Well I finished my new parting tool holder today and tried out the Tantung blade for the first time. I increased my old Red Cut Cobalt cutting speed from 360rpm to 1000rpm at .0012" per rev and my cut time per piece is down to 16 seconds flat. This tool is amazing!!

[BadDog]

At the risk of suggesting a "throw money at it" alternative, I've never looked back since I went to carbide insert "blade" parting blades. These things just work SO nice, but you really have to accept and embrace automatic feeds that will at first curl your toes (or at least they did mine).

[websterz]

I maxed out my RPM's today, all the way to 1400, and kept the feed at .0012 per rev. The tool ran like a champ. I'm going to bump the feed up to .002 and if it seems to tolerate it well I'm going to be well satisfied.

I ran a carbide insert tool quite a bit when I did this for a living. For my current needs $10 a pop inserts are not really necessary. If I was running bigger harder material I might consider going to them. For now the Tantung is doing an amazing job. For the price I paid for 2 blades carbide will never even come close! $60 bought me a lifetime supply of parting tools.

[BadDog]

Very cool, and glad they are working for you. Haven't had the pleasure of Tantung (or Stellite) parting tools, but I LOVE the bits. However, I wonder if you might be running a bit fast even for those parting blades? On steel (the sizes I typically am running) I don't part at those speeds even with carbide inserts, or did I miss something and this is aluminum?

Edit: Nope, I see it's 4140, and that starting surface speed of ~200 SFPM on Tantung wouldn't be so bad I guess with the rapid reduction in diameter while parting.

And speaking of those inserts, I don't recall ever changing but one, so if I'm not mistaken, I'm still on my second of a pack of 10. I think I got that pack of 10 off ebay for less than $40 total, so I'm happy too. Likewise for my topnotch. Maybe it's me being so careful with them, and the comparatively small amount of use, but those inserts also just seem to last and last.

[websterz]

So far I have made just over 100 cuts in 9/16" material and honed the cutting edge once. It didn't really need it but better safe than sorry.

[websterz]

You were right Russ. At top speed I was starting to get some erosion at the end of the tool. I've backed it off to my original 1000rpm and will see how well it holds up. Even at the reduced speed it is worlds beyond the performance of my old Red Cut Cobalt tools.