Newbie looking at 6040 (China CNC) for polypropylene 15mm sheet

[Boyan Silyavski]

you need more like 22000rpm and 3000mm/min with 3 flute roughing bit at 3mm depth of cut. heavily cooled by air at least. But that are speeds and feeds for very rigid machine or a mill

0.07mm feed per tooth on aluminum? i dont think so, especially on your machine. Lower the depth of cut and look to eliminate any chatter. Or lower feed per tooth to 0.3 lowering your feed speed half.

Just make a video to hear whats going on and we will tell you whats wrong...