T-15 HHS

[Bob Quale]

I use HSS cutters with some amount of cobalt in them.

While looking for some new cutters I spoted T-15. What is its' application and would it stand up to the pounding in a shaper? I would also like to use it on my lathe for better performance than HSS.

Any ideas? Thanks Bob

Ps- I see I spelled HSS, HHS in the title, but can't seem to fix it. Sorry

[This message has been edited by Bob Quale (edited 02-03-2003).]

[Thrud]

Bob
T-15 is excellent for interupted cuts and HD use including stainless steels. It is much more difficult to grind that "regular" HSS but its edge life and high hot hardness make it an excellent alternative to Carbides - only much, much tougher!

You should find it a boon to your shaper tooling if you are using the shaper a lot.

[Bob Quale]

Sounds great! But there must be a down side? Carbide is great but I have no way to resharpen efectivly, so it gets expensive. It seems T-15 can be sharpened with my regular tool grinder with white cup wheels or do I need something else?

Thanks Bob

[Forrest Addy]

T-15 is great stuff and holds and but it's brittle. I can't imagine it holding up in a shaper without a positive tool lift on the return stroke.

It's also very abrasion resistant making it difficult to grind. I used to use it for boring stainless double suction pump cases. It would tolerate penetrating the work hardened surface better than any other tool steel but it was a bear to sharpen.

I always liked MoMax Cobalt for shapers. It's tough and resists edge cratering.

[Thrud]

Bob
It is tought to grind with Aluminum Oxide wheels - Norton SG (Norzon premium) wheels work better, but CBN works best. The pink ruby (Ceramic) wheels should also work well, but I have not tried them. If you are stuck the SiC will do in a pinch. Don't dunk it in water to cool while grinding - grind dry or grind with lots of coolant on the surface grinder. Regular HSS can be cooled down with water.

[This message has been edited by Thrud (edited 02-04-2003).]

[Bob Quale]

Oopps.

I got some T-15 and ground it. I dunked in water for coolant. It seamed to work fine as far as grinding goes. I have a carbide grinder with white wheels. It was slow but ok. Why no water for cooling? OK to continue using the white wheel?

Bob

[Thrud]

Bob
The thermal shock can crack it - same with carbide. They have excellent hot hardness, but like most things cannot stand sudden radical temperature changes. If you constantly dunk it it water so it barely gets warm that is alright. But letting it get really hot and then dunking - is bad. You are better to let it get hot and aircooling than to dump in water. Constant flood cooling will also prevent overheating.

The problem with thermal shock is one of the reasons that modern carbides are recommended to run dry rather than wet. When using colling, most operators fail to provide massive flood cooling to properly cool the carbide and thermal shock results when the 2000* surface of the insert is hit with 40* coolant - thus cracking the inserts.

[Bob Quale]

It is amazing the onfo on this fourm!

Thrud, thanks for the replies. I think I was having the thermal problem with the carbides, that you speak of. That is why I went back to HSS in the first place. The carbides were getting expensive. When ever I grind my cutters I never let them get hot in my hand. I grind a little then dunk. That must be why I got away with it. Had I gotten thermal crackes I never would have figured out why. When I cut with the T-15 should I use a spray bottle or brush something for coolant or just run dry? My flood coolant makes too much of a mess in the shop. I'm tring to get away from it. I was turning down a 4" diamiter piece of annealed cold roll. I was taking .020 cuts with out a problem and using a spray bottle-oopps. Well, wet or dry and how deep? What do ya think?

Thanks Bob

[Thrud]

Bob

I use carbide dry all the time. The T-15 you can run dry, but you will have to sharpen it more often than if you use flood cooling. I do not use cooling just because of the mess.

Never let the bit get too hot to hold in your hand when grinding!