[DampRobot]

I'd run at around 8 IPM and about 3000 RPM, but that's just me. I'd primarily be worried about breaking the tool rather than, say, chips melting or chip evacuation, especially since you're using flood coolant.

There's probably a reason why you need a 3/16" cutter, but if you have the choice, 1/4" cutters are really the "sweet spot" (at least in my experience) for cutting aluminium with coolant, because you can push them up to some quite high speeds without worrying about breaking the tool, or the part vibrating too much. I've done 1/4 inch passes at 18IMP and around 5000 RPM with flood coolant and 1/4" two flute endmill on a relatively "weak" machine, a Tormach. On our Haas, I probably wouldn't push a 1/4" endmill past 15 IMP because we only run mist coolant on it. In general, 3/16" endmills I'd be wary to push too much, because we've broken the only one we have in the shop many times by being too aggressive.