For some strange reason, I want to shoot a youtube video, showing how I remove an ungodly amount of material with a carbide drill, on a CNC mill.
It would be, sort of, something like a "hold my beer and watch this" stunt.
The point is to just make as many chips as fast as possible, so to speak.
I would use something like 5/8" drill, drilling a 1/2" mild steel bar.
My question is,
1) Can I run this at 2,500 RPM
2) Do I have to use coolant or not with a carbide drill
3) What would happen if I do NOT use any kind of peck or interrupted drilling, and just plunge into the material -- would the long chips be a real hazard?
Ignoramus1116 fired this volley in news:N9Wdnf23Re2Q8jXQnZ2dnUVZ email@example.com:
Oh... I thought at first you meant "high metal removal rate". You mean "low BAR removal rate". Ig, the drill's bigger than the bar.
But that's just little stuff!
The heaviest "drill hogging" work I've seen done on steel wasn't with carbide, but with HSS with through-the-spindle cooling.
Then there was some really heavy turning in Vallejo, with the lathe taking out about a 3/8" deep chip at about 3/8" feed per revolution. Of course, it wasn't really "big" work... just 12" or 16" prop shafts, but I'll bet they get even heavier cuts on the _really_big_ shipyard lathes.
I saw one guy in Vietnam drill about .062" per revolution with a 3/4" bit. He got away with it with no damage, but even with coolant, the chips came out of the hole smokin' and blue. It was spectacular and smelly, too, because he was using heavy sulfured oil for the coolant/lubricant.
High tooth loads on carbide can be tricky, because it's so brittle. And of course, it depends upon whether or not it's an indexable insert bit or solid carbide (though I don't want to pay for new solid carbide in that size).
I didn't check my tables, but I think 2500 RPM is a little slow for that "small" a carbide bit at high feed rates. You'll have to talk to the carbide guys... I use mostly HSS with a few indexable bits for boring and finish work.
Be aware that on breakthrough with extremely heavy feed you can acidentally pull the drill down out of the chuck...worse yet, if you pull the work up out of your vise etc it will begin spinning and then finally it will launch.....
It might be safer for the camera to do this on a lathe, so the chips and oil aren't flying all around.
My little 3/4 HP Clausing mill can whip big smoking blue drill chips around that keep me from reaching the switch to shut it off. When they become long enough to slap and hang on the column they start to wind around the bit in a big wad, which traps the emerging chips and obscures the effect.
We had a customer that made "screens" for huge pulverizers/shredders. These screens were big sheets of steel over 1/2" thick that had thousands of holes drilled in them. The operation seemed to take more time to index the sheet than it took for the drill to poke through the steel. The tool we were supplying them was a carbide drill with a special point geometry that was proprietry to the manufacturer. Only certain grind shops had the licensed software to reshapen the points.
I think I have some of the drills hanging around; I doubt your machine could do it justice but if you want to give it a shot I'll check it out on my end.