need help: burning flutes...


Finished my mpcnc and making my first tests.
I trying to cut an mdf wood but i already burn two flute in the process.

1º test was an 3mm flute: is turn black and stop cutting the wood and was result to cnc start to missing steps on the x axis. I was cutting with 20mm/s and Z at 3mm each pass, 20000rpm
2º test was with an 6mm flute: reduced the speed to 10mm/s, 1.5mm each pass and 15000rpm. Cutted more, but after a will same result… The flute tip was black and stop to cut.

The flutes used was the next i buy from china:

So far the two test made i broke two flute and i do not know what i doing wrong…
Any idea what can be the problem? bad quality flute? cutting too mutch on the Z?

Clean out the cut as it goes, vacuum or air blast you might be re-cutting all the debis. change your step over to 45%. Try going slower with the spindle speed. These should not be burning at all, there is something a bit odd about the shape of those mills they might be side cutters and not and end mill. can you send a pic of the tip.

found the problem… resuming, i m a noob and need to learn a lot about cnc.

buyed an bosch flute of 8mm to cut mdf and worked, the flute cutted the mdf like is was butter. this flute was expensive 26 euro, can some one can give ebay link to cheap and good flute to cute mdf? the one o buyed simple do not work.