(Attempt to start some good threads)
This is ass backwards to what most think.
OK...You have a machine, it goes 20 grand rpm, cat 40 spindle. Or, you have a 60 grand spindle, hsk spindle. What rpm do you program?
Your answer might be the rpm given by the manufacturer. Thats the answer the left side of the brain gives, but the right side is a bit more complicated and actually works backwards, giving awesome results in both cuts and cutter wear.
You have to program feedrates, then set the rpm to fit.
Explained: You program a part to cut, 200 ipm. You go run it and find due to corner control, or corner slowdown on the control, its really running at 85ipm most of the time. (a kickass programmer has a feel for corner control on all his machines and can predict the feedrates) You need to set the rpm to match this, and inhibit the feedrate to 85ipm as much as possible.
Now, cutters last forever, finishes are the same all over, machines last forever.