Spindle - 2.2Kw, i'm using a mist cooler, pressurised coolant and air adjusted to make a large droplet mist. Aluminium all 6082

So it sounds like i'm doing a few things right but a lot wrong, i'm using adaptive tool paths in fusion.

The best success i've had is with 8mm 3 flute carbide end mill - 12000 RPM, feed 2.5 - 3m/min, DOC 5mm, WOC 20% this worked really well for a while but eventually it looked like it engaged a bit to much and stalled and broke.

I managed to break a 10mm end mill, similar settings, stalled really quickly (with hindsight i'm not sure why I did this). I've been using an aliexpress 12mm HSS rougher with good success recently with much smaller DOC to reduce load.

I've broken all my 3 flute 5mm /6mm end mills so far, best success was 16000 RPM, feed 1.2m/min, WOC 20%, DOC 2mm 0.025 feed per tooth.

I think your right with the rubbing, the chips didn't look very big with the 5/6mm cutters, i'm a bit concerned if I increase the RPM to 20-24k I would need to go at crazy feed rates? it looks scary going higher than 1m/min with a 5mm. What sort of feeds are you using at 24k RPM?

I could double the 5mm feed per tooth to 0.05, that would give 3m/min with 20k RPM? I could increase the RPM on the 8mm 3 flute: 16K RPM, 3.2m/min feed and reduce DOC?