1mm end mill depth of cut in aluminium.

[JAZZCNC]

No I didn't realise it was bullshit. I thought it was a combination of a fishtail end and a more open helix. I have found end mills with a flat end are much more prone to clagging.

It's mostly down to helix and if polished flutes or not. If you don't need flat bottom cutting then you are always better buying end mills like slot cutters which have more clearence.
For finish passes I actually prefer HSS as the slower feeds n speeds seem to give a better finish.

BTW Sorotec recommend a spindle speed of 50K 7mm/sec feed and 1 or 2mm/sec Z feed for up to 1.2mm cutters. With those parameters I would expect to melt through the metal unless you clear the debris. Chip size must be fine dust.

Yep it requires lots of chip clearing and it does come off like a fine slurry. I recently visited a place in Leeds who engrave and cut with tiny cutters using 100k+ HF spindles and what came off was like a fine grinding paste. Would you believe they hardly break cutters from actually cutting, they break them mostly when replacing or catching on stuff. However, they grind there own so it's no big deal to them.