How to drill faster in brass

[Boyan Silyavski]

Hi,
have to drill a lot of holes in brass, on the CNC i mean. 3mm as i thread them later to M4. Something similar to grounding bars , where each piece has 15 M4+15 3mm pass trough holes.

Till now i was drilling them using 3mm mill and 16000rpm feed rate like 15ipm and some pech tool path for the sticky chips to go out, which is leftover from the time when i did not use brass bar but very gummy aluminum bars. But now i have 500x30=15000 holes to make so have to speed up quite a bit.

Any ideas? if i remove the peck drilling path things will be speeded, but is it needed for brass ? 8mm square brass bar. Normally i use 2 flute spiral 30 degree fishtail 3mm bit. Problem is i am busy with other work so no time for experiments.

[magicniner]

Brass chips very nicely, you may find you don't get any issues but if you use very localised air you can shift enough chips for holes that depth, I use clip-together coolant pipe with a medical canula needle bonded into the nozzle from the inside,
Regards,
Nick

[Clive S]

Boyan Would a 3.3mm drill be better than a 3mm in Brass?

[Boyan Silyavski]

Brass chips very nicely, you may find you don't get any issues but if you use very localised air you can shift enough chips for holes that depth, I use clip-together coolant pipe with a medical canula needle bonded into the nozzle from the inside,
Regards,
Nick

So you are saying to try 24000 rpm, no peck drilling, blow air and try how fast things could go with that carbide cutter i have?

Boyan Would a 3.3mm drill be better than a 3mm in Brass?

yes, actually i am using 1/8 . was using 3mm on my old flimsy machine cause due to vibrations it was making a 1/8 hole :-)

Anyways i use a spiral pointed machine tap which further drill opens the hole if necessary.

[Boyan Silyavski]

Or would using a drill will be faster? Instead of a milling cutter?

[Lee Roberts]

Or would using a drill will be faster? Instead of a milling cutter?

I would have thought so, the right tool for the job and all that?

Milling cutters are for cutting sideways no?

.Me

[ptjw7uk]

You should also check the drills geometry as a normal drill used on brass can break as it will pull into the hole, possibly not that relevant on a cnc machine as the drill will be restrained by the z axis.
Normally if you drill a lot of brass you can remove the cutting edge with a 'stone'.

Peter

[Boyan Silyavski]

I had a talk with the HSMadvisor maker, so it seems i had that functionality but did not know how to find it.

So according to the calculator it seems drill / HSS/ or mill/carbide/ is almost the same feed rate. But if drill is cobalt or carbide then 1.5x faster. 1000mm/min and 1500mm /min respectively.

I use the general option " Other non ferrous alloys" in stead of "low lead brass " or similar as the latest give me too slow feed , slower than aluminum. So it seems my brass is different, as i know for a fact that it machines and drills much faster than aluminum.

Will experiment tomorrow to see how fast it could go in real life and report back.

[magicniner]

Boyan,
I'd definitely use a drill bit, not a milling cutter,
Regards,
Nick

[sinnsvak]

And pecking could be reduced to short-stops to just break the chips.