Okay, so. When you're running aluminum, you just crank the RPM up as high as it will go, and feed as fast as you like.
Copper, you turn the RPMs down a little bit, or up the feed a little, because it's gummy, and so the chip gets knocked off the tool and doesn't build up and clog the flutes.
But Stainless? Work-hardening issues aside, why on earth does my dad always yell at me to run tools slower, slower, slower? I mean, this one part that I just finished programming the other night. I try doing something like 3500 RPM and 5 IPS on a .281 drill, but he yells at me and tells me to crank it down to 1800 RPM and 3 IPS. With flood coolant, so long as the feed and RPM are proportional, there shouldn't be any work-hardening, right?
I genuinely am trying to become a better machinist, and would love an explanation, because my dad is terrible at explaining WHY and giving me an idea of HOW MUCH I need to slow things down, aside from, "Just do it that way".