Problem cutting brass

Hello everyone,

I'm pretty new to milling and having some trouble milling brass sheets. I am milling 0.01" thick brass in 2 passes at about 0.005" and running the mill at 4-5 ipm and 4500 RPM with a 4 flute 1/8" carbide center cutting square endmill.

I tried running the mill closer to what some of the calculators said the mill should be at but I found that this gave decent results.

Any suggestions for the speeds and federate for milling 0.01" brass with a 1/8" endmill??? I'm sure that what I am doing is incorrect...

The problem is that occasionally, the cutting edge on the head of the endmill forms a cap of brass over it. This was not really a problem before but now we are milling assemblies and after the first part is made the end mill develops this cap over the head and can no longer penetrate the brass.

I am not sure if it is a problem with my speeds and feeds, anatomy of the endmill, or lack of lubrication.

Also, my machine can not exceed 6500 RPM.

Thanks!