Tialn coated vs. uncoated?

[Driftwood]

Question for all the seasoned vets out there...

Does the Tialn coating on a carbide endmill increase the tool life enough to make it worthwhile for price? (Or any other coating for that matter?)

When I talk to my supplier, they tell me the coating adds about 20% to the tool life. Well, thats all well and good for say a 1" endmill that costs $120 uncoated and $150 for coated. Its almost worth it...

But if I look at smaller endmills, say a 1/4", its about $10 uncoated and $15 coated. Go even smaller, like 1/8" and the coating doubles the endmill price!

Supplier says I can run a little faster with the coated, but not much, maybe 5-10%. Thats not enough to make it worthwhile for me.

So what do you guys think? This is just a general question for all materials and conditions, but in particular, I'm thinking about a job where I'll be working in 316SS with some small cutters.

[HobbyCNC]

Originally Posted by Driftwood Question for all the seasoned vets out there... Does the Tialn coating on a carbide endmill increase the tool life enough to make it worthwhile for price? (Or any other coating for that matter?) When I talk to my supplier, they tell me the coating adds about 20% to the tool life. Well, thats all well and good for say a 1" endmill that costs $120 uncoated and $150 for coated. Its almost worth it... But if I look at smaller endmills, say a 1/4", its about $10 uncoated and $15 coated. Go even smaller, like 1/8" and the coating doubles the endmill price! Supplier says I can run a little faster with the coated, but not much, maybe 5-10%. Thats not enough to make it worthwhile for me. So what do you guys think? This is just a general question for all materials and conditions, but in particular, I'm thinking about a job where I'll be working in 316SS with some small cutters.

Lets say that 20% is in fact a good number...defined as what? Time in cut? Total metal removal? Will the coating allow "faster" metal removal and still allow 20% more cut time? Maybe the coating allows 50% more MMR? Time is money right? Even if the tool does not last longer, if you get the MMR up due to the coating, then the added cost is easily justified.

Look around a modern job shop....see any uncoated carbide being used? I'll bet not!

[ajl6549]

I would sat if you don't need it don't use it. If you cutting difficult to machine mat'ls then it might be justifide, or if length of your finish etc. dosn't hold up. Every app. is different and requires a different approch.

[tobyaxis]

Originally Posted by Driftwood Question for all the seasoned vets out there... Does the Tialn coating on a carbide endmill increase the tool life enough to make it worthwhile for price? (Or any other coating for that matter?) When I talk to my supplier, they tell me the coating adds about 20% to the tool life. Well, thats all well and good for say a 1" endmill that costs $120 uncoated and $150 for coated. Its almost worth it... But if I look at smaller endmills, say a 1/4", its about $10 uncoated and $15 coated. Go even smaller, like 1/8" and the coating doubles the endmill price! Supplier says I can run a little faster with the coated, but not much, maybe 5-10%. Thats not enough to make it worthwhile for me. So what do you guys think? This is just a general question for all materials and conditions, but in particular, I'm thinking about a job where I'll be working in 316SS with some small cutters.

www.hanita.com
www.duramill.com

These two companies will explain coatings better than I can. Uncoated for like Titanium materials, and Coated for just about everything else. Coatings help to keep an End Mills cutting edges sharp, from breaking down, or heating up too much. Coatings also help chip evacuation by providing a smoother cutting surface.

[kalmah]

I don't agree with your supplier. My personal experience on 316-l (I machine its material most of the time):
- The TiAlN coating adds about 100-200% to the tool life on stainless steel. The coated tool are 100% justified.
I agree with Tobyaxis. A lot of coating don't improve the tool life for the machining of titanium.

[cdlenterprises]

You have to be careful when you get into the world of coatings. Different coatings give you different advantages on different materials. The main advantage of the TiAlN coating is wear resistance. The coating is considerably harder than the carbide that it will cover so the edges of the tool will last longer. This particular coating needs to reach a certain "activation" temperature before it will work, however(I think it's around 700-800 degrees). The way it was explained to me is that when activiated, the coating provides the wear resisitance of a ceramic cutter with the strength of a carbide substrate. One of the ways to activate it (or reach the temp) is to increase the rpm. Since Feedrate = RPM x Feed per tooth x # of flutes, the higher the rpm, the higher your feedrate.
That's some of the theory behind the coating.
However also keep in mind that no matter what coating you have on an endmill,you can only push a 1/4" endmill through 316 S.S. so fast before....BINK!!! you lose it.


To make a long story short, the wear resistance of the coating is well worth the price in difficult materials. As far as feedrate gains, that's up to the machinist. Remember no guts no blue chips!

[knot2swift]

TiAlN does work best on things like stainless 316. The price is 20% more with 100 to 200% more life.

If you wish to take matters to the level of "Jedi Knights" Try variable pitch angeled end mills. It's the latest craze for not every flute is 90 degrees apart so there is less chatter.

Happy new year.

[CarbideBob]

Originally Posted by Driftwood Does the Tialn coating on a carbide endmill increase the tool life enough to make it worthwhile for price? (Or any other coating for that matter?) Supplier says I can run a little faster with the coated, but not much, maybe 5-10%. Thats not enough to make it worthwhile for me. .

Hmmm, seems your supplier doesn't know very much.

TiAln coatings are made for speed. As applied they are relatively soft. As noted above you need lots of heat to convert the AL in the coating to Aluminun Oxide. Uncoated you may be limited to say 300 SFM. Coated with TiALn you can run up to 1200-1600 SFM so your are looking at 4X the speed. If you ran an uncoated endmill at 1200 SFM it would die almost instantly.
If you don't push the speed up high enough to convert the coating you won't get any better life than uncoated. The speed at which this happens is dependent on material, hardness, and width of cut.
TiAln coatings come in many different flavors. Some will have a layer of TiCn underneath to help at lower speeds.

TiN (gold colored) and TiCn (bronze colored) are the most general purpose coating. They are harder than the carbide as applied and work well at mid range cutting speeds (300-500) SFM but they burn up at the speeds at which you would run TiAln

None of these coatings work on Aluminum cutting. Here you would want ZrN of TiB.

Coatings can increase life from 0 to 800 percent. Each has it's own purpose and speed ranges. Some coated endmills will also have the cutting edges "honed" to reduce chatter. The grade of carbide underneath the coating can also drastically affect tool life.

The only way to really know is to test them. The harder or tougher the material and the higher the speed the more you will benefit from a coating.
High production users almost always use coated tools.
Bob