Peck, speed, feed for drilling graphite?

[g huns]

Gotta drill 1704 .035 diameter holes in some graphite electrodes. When I did the prototype, I think I was takin it too easy, 30,000 RPM 6 IPM and full retract pecks every .025. I only needed 6 trodes then, and if I remember right it took about an hour each. Oh yea they're .300 deep, using .035 solid carbide circuit board drills, 71 holes per electrode. I can set up 8 trodes at a time. Just wondering if anybody out there is a graphite drilling guru and can point me in the right direction. The drills have about .450 of flute and a fast spiral so I'm wonderin if I really need to peck.

[betts]

ghuns, I would drill them at 9000 RPM and 10 IPM and peck every .050 (about 1-1/2 x D).

 

You don't say how deep you have to drill, but how far the drill is hanging out makes a BIG difference. I don't have 30K spindle, so it isn't an option for me. Only have 10K.

 

Seiously, it would be worth it for that many holes to practice on scrap and "push 'er till she breaks, then back off a little" as what grade of graphite will make a difference, and your tooling. Also Ghuring drills are some real nice ones in the small stuff, unless you have diamond.

[Lucky]

30,000 rpm

20 ipm

No peck (peck 0.050" to 0.100" if you're scared)

Pecking costs a lot of time. Practice in a scrap chuck of mat'l.

[K Reed]

I never peck in graphite either, but .035 might require some material evacuation.( full retract) I'd also say push it in some scrap, then back it off a tad.

[Mjölnir]

Lots of people use to light a feed rate when drilling it seems. 30000 RPM x 6 IPM is only .0002" feed per rev. I'd start at .001" per rev which is 30 IPM, and .1" pecks with full retract.