Need Help!- Drilling 314 SS 2 inches deep

[Vern Smith]

We have a short job, 24 .375 holes in 314 two inches deep. We don't do much with stainless and are not in a big hurry to get it done. Minimal damage to the drill bit is more important than production speed. The plan is 200 to 250 RPM and 2.25 IPM feed. If that's off base would appreciate your input.

My concern is technique. Dry or with flood coolant? Go all the way in one shot or peck drill it?

Vern

[RICHARD ZASTROW]

I'd use the drill manufacturers recommended speed and feed. Feed enough to avoid work hardening. So far not much new info. LOL

Try this: use a coolant thru the tool drill with an air blast micro drop dispenser. Blows the chips out as it feeds. Chips fly all over the place, wear eye protection.

I realize this is an expensive cure for one job, but you will have the system fo future drilling and milling work. I used it a lot for "T" slot milling. Works for me.

Dick Z

[Khalid]

Hi Vern
Recently i am doing the same drilling jobs on tube sheet and baffles.. You can see in the following thread , how i get it going with HSS drill bit..
Just read to the end and you will see how i succeed with the help of community..You will be able to do drilling using my experience..

http://www.cnczone.com/forums/showthread.php?t=107299

YouTube- CNC Drilling Holes

[Vern Smith]

Thanks Khalid,

I drilled the holes today, broke a carbide spot drill at 400 RPM 2 ipm so I slowed it down to 1 ipm. Did all 24 holes with the same 3/8 cobalt split point 135 degree drill. It did chip the edge of one flute from the center about 1/2 way to the OD. I used 300 RPM and 2 ipm. I noticed the spindle load meter gradually increased from the 50% neighborhood to the 60% neighborhood at the end. I used flood coolant and I would guess the part was about 100 degrees when I removed it from the vise so I don't think heat was ever a factor to be concerned with.

If I had to do as many holes as you are doing I would look at carbide as well.

Vern

[Khalid]

No Problem..
Carbide is very brittle in nature and i lost two on the above job.. so i experimented with HSS and for 60mm deep i am using a single HSS 8mm drill for 224 holes...just resharpening after each 10 holes...

[Cknoble1]

I usually run around 250-300 rpm's and set my feedrate at 2.5ipm.
make sure you have coolant flooding the drill. If programing manually or with mastercam set your peck clearance to .0625 and your peck depth to .125... This will be efficient for your tooling... Use CARBIDE drill. youre initial cut can go the full .375" depth then .100-.125 increments until you reach 2". shouldn't take too long to drill a hole.
Good luck Bud.

[Cknoble1]

Do not go full depth in one cut.