for a past few years I've been struggling with slotting aluminum with small 3-5mm tools.
Like right now I'm machining small-ish parts from these big 2x3m 5083 H111 sheets. Cutting (essentially slotting) around the parts at 20 000rpm at 8mm/sec with cutting depth of 1.5mm with mist coolant and I just can't push the machine harder unless I up the rpms and that helps only so little.
All the calculators are suggesting I should be flying at like 20mm/sec or faster but that would either break the carbide, TiAIN coated endmill or coat it with molten aluminum within seconds. I also keep seeing these videos of people slotting at like 12-15mm/sec with 4mm endmills with no coolant and they go through the material like butter.
What am I doing wrong?
The rigidity of the machine is not a problem, neither is the spindle power I think.