Hi, I'm very happy with HSM and usually the speeds and feeds work great. Thanks : ) Recently, I was milling AW 5083 with a 2 flute carbide. It went like a charm for 1h but then nothing worked anymore. 2 cutter full of melted aluminium and a broken 3 flute. So, something has changed. But cooling was no worse than before and the CNC had no malfunction. Might it be, that in this problematic spot, the AW 5083 was of a different strukture that was problematic to mill ??? In a 200x140x20 mm slab ? After some google research I found a recommendation to increase the chipload to 0,025. So and changed it from approx 0.0144 (HSMs value at F=100 and S=69) by using the F-slider to 0,025 (F=173, red). Also I had to use a single-flute (nothing else left) now and I got nice chips and could proceed. (4mm carbide, single flute, 18000rpm, 450mm/min, slotting, z=2mm) As the F tooltip said, the finish is not as smooth, but increasing the chip-load seemed to be the only solution to this soft material. I guess that also the 2 flute cutter will perform good as well with this high chip load. So what could have been the true reason for the problem ??? Could also be disgraded cutter, true ? I'd love to decrease th chip-load to 0.02 to get a bit better finish ... but for me, it is hard to hear 20 € snap too often :-( Ideas and suggestions welcome : )