If you have the rigidity, climb milling rules in most circumstances. Machined tons of alumium if possible use concentrated compressed air instead of coolant. The best setup is with an Exair Cold Gun. As long as your cutting alloy aluminium vs pure/gummy, coolant isn't need if air is used. As mentioned above 2 or 3 flute endmills are better for chip evacuation. Under ideal conditions in high production have used high helix endmills in excess of double diameter depth of cuts. Ear plugs required.