[CoolHand]

I'm using a 1/2" 4 flt solid micrograin carbide square end mill to cut 0.75" deep slots in 6061 T-6 aluminum.

I'm spinning the tool at 5000 rpm, feeding it at 40 IPM at a DOC of 0.1"

That gives me .002 IPT, which I thought would be easy enough for the carbide to handle.

Wrong.

I have cut maybe 1800 linear inches with this tool, and already it is destroyed.

Not broken, but the ends are chipped, the flutes are chipped, and it is now leaving swirl marks all over. Basically, its done.

Whats wrong? I am using a water soluble lard oil cooland/lube, mostly to flush the chips out of the slots.

I've got to fix this somehow, as ruining a $40 endmill every time I cut this part is really cramping my profits.

I know something is wrong, but durned if I can figure out what.

Could it be poor quality tooling? I've been contemplating switching to indexable endmills, but I want to be sure that this won't happen with them too.

Any help would be most appreciated

Thanks for your time.