[JohnJW]

Here's the deal with cutters. When the mfg tells you to run it at 800sfm and no coolant. That's what they mean. The new coatings are heat activated. Coolant will thermaly shock and chip carbide at much above 500sfm. You are not only waisting time by piddleing around at 10% but you are killing the cutter. Use the mfg recommendations and you will not only improve your cycle times but you'll improve your tool life as well.
This ain't like the old days where we roughed at 300 rpm and 3 ipm.
You got to turn it up.
When you buy those tools you also bought all of that companies technical support.
Use it.
If you can't make the min sfm...you are using the wrong tool. Or you need to think about a faster machine.

Thanks, I'll aim for 100% feed next time but what type of end mill do you guys recommend if I need to go down as small as 1/8" or even 1/16" to clean out pocket corners or slotting down to diameter depth on aluminum with a 12,000rpm spindle?

[PBMW]

John
Let me rephrase my last post.
You need to be at least at the manufactures recommended feeds and speeds for your material. I use a bunch of half inch variable helix AlTin coated endmills. I just got done with a job where I was profiling 4340 at better than 1000sfm. .375 doc both radially and axially. That's 7700rpm and 100ipm. No coolant. I could have turned it up. I called the manufacturer and asked what I needed to do to and they told me to turn it up and keep at least half the tool dia in the cut. Otherwise it would cool and go away.
So, Call your tool rep. I get carbide from Lakeshore and Carbide Connection. They are happy to help you with feeds and speeds.
The big thing is to not second guess them. Do what they tell you. Sure you might trash an endmill. So what? You will have learned something. You might find it's faster. And that makes you money.