Quote:
Originally Posted by techhelpbb
Well I am confused then.
Cause I not 7 days ago used a TiAlN 1/8" end mill, 2 flute on aluminum.
With coolant and it was hardly a new end mill for that purpose.
I am not the only one either.
So I guess the question I have is at what operating temperature is this coating appropriate?
Since the question here appears to come down to whether or not it can reach that temperature.
Answering my own concern:
I have a long commute so I decided to call around to Duramill and Niagra.
Spoke with the technical folks not sales.
The reason the coating operating temperature is not specified is apparently because they consider the TiAlN coating inert.
It shouldn't want to bind chemically to aluminum any more than Titanium (no affinity according to Niagra).
The coating provides hardness and durability till the yield temperature well over 1,000 degrees Celsius.
This differs from aluminum titanium nitride which is high in aluminum and therefore is an active coating.
The issue they clarified is that aluminum will of course melt well into the safe operating temperatures of these bits.
So you don't have to hit a certain temperature to make them work.
However just because the bit will withstand these temperatures does not mean the aluminum you are working won't melt and wet the bit.
Obviously once the aluminum melts and wets the bit welding will soon follow.
The reason my machines are not experiencing that issue is because I do not cut aluminum without coolant.
Therefore I am cooling everything.
I do not consider the cooling to be really heavy duty so the bit does get hot.
However the aluminum being worked is basically a heatsink and the coolant cools that.
The gantry mills I have used TiAlN with are pretty rigid. I have seen much worse.
Also I am aware that aluminum tends to melt so I take measures to keep moving.
This is why there is no minimum desirable operating temperature specified.
This is also why it works for me.
I told both companies that I've used these with aluminum and no huge red alarms went off.
However I still agree a slower spindle is desirable for this purpose.
It would eliminate the need for the tool that could be a bit more expensive.
Additionally it would reduce the risk that a slow cut would weld.
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If you have a choice you would never use TiN, TiAlN, or AlTiN in Aluminum. If it was all you had, you could use it without immediately destroying your end mill. All the things Scott said are true though, regarding surface finish and BUE. You can definitely notice the latter occurring.
If you tried to run one of those end mills under aluminum specific parameters (1000+ SFM, .003"+ chip load) you will load it up and break it-guaranteed. This is as much because of the geometry being wrong as it is because of the coating, as the only tools that are ever coated with those are meant for ferrous materials.
I'm not sure why they told you that you don't want to run the tool at elevated temperatures. I forget where it is exactly, but somewhere between 700-800C the coating dramatically increases in hardness. As previously mentioned this is why people don't cut ferrous metals with coolant when using those coatings.