Questions on using a moving gantry style mini-mill...

[Boyan Silyavski]

This is Kyocera carbide micro bits feed and speed chart. They are definitely one of the sharpest and overall best bits around. So if you are using inferior -30% at least on all data.

Vc - cutting speed
f - chip load or feed per tooth
Fr- feed rate mm/min
D- diameter of carbide bit
U- number of teeth on cutter
p=3.14


Ae - side removal
Ap - face removal


1.
determine spindle speed rpm/min depending an operation/roughing, slotting, finishing/


RPM=(Vc*1000)/(p*D)
so
RPM=(150*1000)/(3.14*2)=~24k RPM, so you are spot on here




2.


Calculate feed rate mm/min:


Fr=f*U*RPM
so
Fr =0.024*2*24000=1152mm/min for slotting

=0.002*2*24000=96mm/min for finishing


That all on a mill with very good cooling and chip removal. Diameter depth and 30% tool engagement

So if you play with the second formula you could easily see why you can no make a nice finishing pass. cause for 800mm/min feed you will need to have the spindle at 8000rpm, not 24000.

Now lower some percent that you ar not cutting on a mill with jet cooling the bit...

And bear in mind that the first speed calc is most probably for roughing bit, because that's how typically is done, that's why seems so fast.

From my experience there is no big science here, i have tested cuts on various machines and the only thing that really differs is the depth of cut that could be achieved with a particular machine.