Drill .059" hole 1.200" deep on Stainless Steel 316L

[liusvet]

I'm on the middle of a project where need to drill a 1.2" deep hole .059"diameter on 316L. I'm using Mitsubishi drills and what they recommend looks a little bit aggressive. No pecking recommended by vendor. The drills are coolant thru. Got high pressure coolant set at 1800 PSI. Machine: ECAS 20. Have someone drilled this size before? Please advise.

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[warrenb]

If you peck don't dwell. 316 work hardens. I haven't had any problems using smaller holes in 3/16. Just my gut feeling... 2500 rpm 2" feed .03 pecks (NO DWELL). Someone will complain about my feeds and speeds so figure one that's best between your machine and the drill bits.

[gizmo_454]

First off, let me say that I have not had the pleasure of drilling that small of a hole that deep. We do, however, utilize Mitsubishi drills in many different applications here at our shop and they are an excellent drill!

Depending on where you are getting the feed/speed information, it can vary. If you are talking to the Mitsubishi rep or engineer, then they are probably fairly reliable. At least they are with the rep in my area. If you are getting them from the Mitsubishi book, then you will have to wing it a bit. If you use the book's values, they will work great in 303/304 stainless. 316 is a bit tougher and will probably require somewhat slower speed, and possibly a lighter feed.

As to the peck, no peck scenario... Assuming you are just drilling plain old 316/316L stainless, if you have 1800 psi through the drill in a sealed collet, go for it. That is what the drills are designed to do. You will want to spot it first, of course, using another drill of the same size and must be the same drill point angle. Ideally, you would use the shorter version of the Mitsubishi drill you are using and punch it in 1x to 3x diameter to give the 20x to 30x diameter drill a good hole to follow. If, however, you are running 316 Condition B, or implant grade 316, all I can say is good luck! Both of which eat tooling and require a significant reduction in speed. And in the case of the implant grade 316, nothing we did could break the chip so we were forced to peck. We pushed the feed rate literally to the point of exploding a drill and the chip still wouldn't break.

Now that I am done rambling, I hope that something of the above information is useful to you. If not, there's always the print it out and use it for toilet paper option!

Best of luck to you!
Mike

[liusvet]

Was able to drill 3 holes until the drill broke. Ran at 3000 rpm and 3 ipm Pecking .01 Today will try slower RPM and if it goes fine will increase the peck amount. Tried without pecking but couldn't drill any hole. I'm machining the medical grade 316L

[liusvet]

First off, let me say that I have not had the pleasure of drilling that small of a hole that deep. We do, however, utilize Mitsubishi drills in many different applications here at our shop and they are an excellent drill!

Depending on where you are getting the feed/speed information, it can vary. If you are talking to the Mitsubishi rep or engineer, then they are probably fairly reliable. At least they are with the rep in my area. If you are getting them from the Mitsubishi book, then you will have to wing it a bit. If you use the book's values, they will work great in 303/304 stainless. 316 is a bit tougher and will probably require somewhat slower speed, and possibly a lighter feed.

As to the peck, no peck scenario... Assuming you are just drilling plain old 316/316L stainless, if you have 1800 psi through the drill in a sealed collet, go for it. That is what the drills are designed to do. You will want to spot it first, of course, using another drill of the same size and must be the same drill point angle. Ideally, you would use the shorter version of the Mitsubishi drill you are using and punch it in 1x to 3x diameter to give the 20x to 30x diameter drill a good hole to follow. If, however, you are running 316 Condition B, or implant grade 316, all I can say is good luck! Both of which eat tooling and require a significant reduction in speed. And in the case of the implant grade 316, nothing we did could break the chip so we were forced to peck. We pushed the feed rate literally to the point of exploding a drill and the chip still wouldn't break.

Now that I am done rambling, I hope that something of the above information is useful to you. If not, there's always the print it out and use it for toilet paper option!

Best of luck to you!
Mike

Hi Mike. I'm trying to drill the implant grade 316L. It is hard to break the chip. Drilled 3holes pecking then the tool broke. Will try slower RPM today. I tried to drill without pecking but broke so many drills.

[bostosh]

Do that manually on an old Moore Jig Borer, Easy stuff

[warrenb]

It seems counter inturitive but lower RPM and higher speed in stainless solves some of my problems. Here is an excerpt from "Carpenter Steel Co. Notebook on Machining Stainless Steel."

"to relieve chip packing drills....take 3x to 4x the diameter of the drill on the first bite then 1x to 2x on the second then 3/4x after." On small drill breakage will be excessive if drills are not run fast enough. Bear in mind a 1/16 dia drill cutting at 40sfm should turn at a speed of 2445RPM" "use a "cotter pin" drill with 140degree tip." "316 stainless steel. 15-40SFM and feed rate of .0015 to .0025 per revolution"

Hope this helps. I have found this 65 year old book more useful than most of the modern feed and speed recommendations when it comes to stainless.

[z369]

You should really look further into the tool makers recommendations. I don't run any Mitsubishi drills, I mostly run Guhring and they recommend pilot drilling a hair over the deep hole drill size. You should be using at least one pilot drill. If you're using a coolant through CARBIDE drill i would imagine your SFM would actually take the RPM requirements above what your ECAS can do ( I'm jealous BTW...AWESOME machine! ).
At, say..165SFM it works out to be over 10, 000RPM. Also, be careful of your PSI rating, with such small thru holes on that drill I'm certain it's building a lot of backpressure and will flex that drill. Also, I would NEVER peck with a coolant thru carbide drill that small.