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Recommend a 12 or 15xd deep coolant thru drill for 304 Stainless-problems

pgmrmike

Hot Rolled
Joined
Jun 24, 2010
Location
Plantersville, TX
Have a job drill drilling 304 stainless, I thought I did my research and bought Guhring 5525 carbide drills with coolant thru. I programmed their recommended speed and feed. Straight thru, no peck. By the time I got 2" deep chips started packing and drill making noise. Been fighting it and only thing that works is pecking .250 deep then feed fast off to -.2" then feed back down fast and slow feed to recommended .1" from re-engagement. After about 2-1/2" deep each peck goes down to .2" then eventually .15".

I am feeding out instead of rapid to keep the coolant under the chips so I dont recut on the way down.

No chips exit until almost to top of the hole.

The chips dont look bad, I upped the feed a bit to make them smaller/tighter but it had no effect. They just wont come out.

I know the problem is my coolant pressure is too low, but figured I would get more depth before it was an issue. I think I have 150psi thru though it blows coolant very well. ( if I am reading it right, 150 is the low end of their recommendation )

I just broke one in the hole, customer material.


4 axis Leadwell V30 VMC Linear ways-not most rigid machine in the world, but more rigid than the Haas' I have run

Guhring 5525 1/4" ( 6.35mm )

304 Stainless

Coolant concentration 12 ( upped it to make chips come out )

Any other tips or recommendations?
 
How deep is the hole? Is it a bottom hole? What are your speeds and feeds?

I'd conservatively use Vc50 F.09 but I'm not familiar with the quality of your brand. Have you tried running internal air gun in conjunction with internal coolant?
 
How deep is the hole? Is it a bottom hole? What are your speeds and feeds?

I'd conservatively use Vc50 F.09 but I'm not familiar with the quality of your brand. Have you tried running internal air gun in conjunction with internal coolant?

Actually 2 holes, first is 3.63" and the other is 4" but neither get even half way there before chips start packing up. I do not have the ability to add air to the blow, may be able to figure out how, but have no experience with it.

Recommended is 130sfm and .005 feed. I am at 1950 rpm and 9.75" IPM feed. I went up to 10.5 feed with no change. Dont want to push much more above recommended. My experience is limited with carbide deep hole drilling.
 
I would call Guhring, they're usually pretty helpful. But it sounds like you're doing what I would do. We were doing some 25xD holes in D2 and Guhring said the minimum TSC pressure should be 300psi. Our coolant pressure wasn't there so we switched to pecking and got through it.
 
I second calling Guhring. I just got done doing some 2.5" deep holes .125 diameter on 304 in a lathe, I am just glad I only had to make a dozen. I feel your pain. It seems the consistency of 304 seems to vary a lot these days.
 
I know the problem is my coolant pressure is too low, but figured I would get more depth before it was an issue. I think I have 150psi thru though it blows coolant very well. ( if I am reading it right, 150 is the low end of their recommendation )

It's most likely the coolant pressure.

When buying a new machine, anticipated deep hole drilling under 1/4" is generally what gets folks to upgrade from 300psi to 1000.

You're right at 1/4", so you don't need 1000, but the ideal pressure would be in the 300psi range. If pecking works without breaking drills, I would continue doing so. Maybe slow the rapids so the retract and reentry give enough time for chips to clear.
 
I doubt that 150 is quite enough for that size hole.

If you have lots to doo, maybe you could just bvuy a booster pump to put in-line in addition to your current pump?

I just bought one like that for $350 off E-bay.
Not a 1500# unit by no means, but it should add a noticeable amount on one lathe that just doesn't have enough currently.


---------------------

Think Snow Eh!
Ox
 
What ive found helpful in the past with 316L is, instead of pushing it for a tight chip the breaks off (and packs) in the hole, back off the feed so you get a string.
Pulse (slow) the feedrate instead of a peck, the chips come out like sausage links, and break OUTSIDE of the hole.

I dont have much experience with 304 aside from turning, but pecking is a no go for me in 316 due the hardening from plastic deformation.
 
I doubt that 150 is quite enough for that size hole.

If you have lots to doo, maybe you could just bvuy a booster pump to put in-line in addition to your current pump?

I just bought one like that for $350 off E-bay.
Not a 1500# unit by no means, but it should add a noticeable amount on one lathe that just doesn't have enough currently.


---------------------

Think Snow Eh!
Ox



If I read this one right - it looks like this one is rated for 200PSI.

It appears to be set up like a booster pump - meaning not tipped down in the sump - so the end should have a pipe fitting on it. (can sorta see it)

So - if you plumb your 150 into it, you should be able to git 350 out the other side.

???

https://www.ebay.com/itm/Walrus-Coolant-1-5HP-Pump-TPH4T5K-TPH4T5KS-A-Stainless-Head-Inlet-Out-Design/113703089069?epid=768787209&hash=item1a793b73ad:g:1fEAAOSwQtdb1daP


If you sort through them, you can find a few stack pumps that have a female pipe end on them in stead of just a screen.
If it has the threaded intake end - you should be able to put it inline with what you have and boost it up.


------------------------

Think Snow Eh!
Ox
 
Call your Guhring Rep!

Call your Guhring Rep!

Call your Guhring Rep!

:D

I love Guhring, their tools are awesome, amazingly FAST, LAST forever, which equals extremely cost effective.

MOST OF ALL - their support is TOP NOTCH. (at least mine is!)
 
Have a job drill drilling 304 stainless, I thought I did my research and bought Guhring 5525 carbide drills with coolant thru. I programmed their recommended speed and feed. Straight thru, no peck. By the time I got 2" deep chips started packing and drill making noise. Been fighting it and only thing that works is pecking .250 deep then feed fast off to -.2" then feed back down fast and slow feed to recommended .1" from re-engagement. After about 2-1/2" deep each peck goes down to .2" then eventually .15".

I am feeding out instead of rapid to keep the coolant under the chips so I dont recut on the way down.

No chips exit until almost to top of the hole.

The chips dont look bad, I upped the feed a bit to make them smaller/tighter but it had no effect. They just wont come out.

I know the problem is my coolant pressure is too low, but figured I would get more depth before it was an issue. I think I have 150psi thru though it blows coolant very well. ( if I am reading it right, 150 is the low end of their recommendation )

I just broke one in the hole, customer material.


4 axis Leadwell V30 VMC Linear ways-not most rigid machine in the world, but more rigid than the Haas' I have run

Guhring 5525 1/4" ( 6.35mm )

304 Stainless

Coolant concentration 12 ( upped it to make chips come out )

Any other tips or recommendations?


You already have tools but I'll chime in anyway.
Use a Nachi MQL drill.
EDP# 1384154
Run a chip break drill cycle.
 
Holes smaller than .25" are tough in 304. I've tried quite a few different Tools, TSC, S&Fs. Pretty much every combination of things, in the end I'm using a black oxide, HSS, Stub length, 135° Drill with a peck the same as the diameter of the Drill. This is where I always end up. Bigger holes offer a lot more options.

For your depth, I'd use the same cut parameters, with a long enough Drill.

Please keep us informed.

R
 
I've had good (but expensive) luck drilling deep in 310ss with 5, or 5.5mm drills.
That's Shirley tougher to drill than 304.

Titex drill with $1 per hole in perishibles.

With HPC.



-----------

Think Snow Eh!
Ox
 
Nothing has really changed yet but wanted to update. The second drill ztarted showing wear after only approx 20 holes. I am assuming its due to the peck. ( probably work hardening every time I pull off ) I was scared to push it further and end up with another scrap part so I stopped pulled off ( only had 2 drills ). Not long after starting this thread I ordered 2 Walter Titex DC150 drills. I checked out the Nachi drills but coildnt find them on my regular suppiers sites. Still an option.

I am checking into a booster pump, at least for the future.

I appreciate all the replies/help. I will update when I get back on them ( probably mid next week )
 
Holes smaller than .25" are tough in 304. I've tried quite a few different Tools, TSC, S&Fs. Pretty much every combination of things, in the end I'm using a black oxide, HSS, Stub length, 135° Drill with a peck the same as the diameter of the Drill. This is where I always end up. Bigger holes offer a lot more options.

For your depth, I'd use the same cut parameters, with a long enough Drill.

Please keep us informed.

R

The only reason I am actually running this job is because the shop that normally runs them doesnt have tsc on their mill. They were using cobalt and did real well till getting near depth. Then a chip would get under the drill and kill it. Sometime make it 40 holes, sometimes only 5 holes. Lost too many to scrap. Initially I searched high and low for a coolant thru cobalt drill ( or powdered metal ) but couldnt find one long enough. My cycle time is almost indentical to theirs now that I have to peck so often, which sucks. The cobalt drills are like $8 and mine are $125......
 
Holes smaller than .25" are tough in 304. I've tried quite a few different Tools, TSC, S&Fs. Pretty much every combination of things, in the end I'm using a black oxide, HSS, Stub length, 135° Drill with a peck the same as the diameter of the Drill. This is where I always end up. Bigger holes offer a lot more options.

For your depth, I'd use the same cut parameters, with a long enough Drill.

Please keep us informed.

R

I'm with you on this. I've given up on drilling into stainless with carbide. I've broken far too many, from different vendors using their starting speeds/feeds. I've resorted to high quality Cobalt HSS drills. Every few weeks I have to dril 5/8" hole in 4.5" SS316, I start with 1/4" pilot hole, then switch to 5/8" drill. The 1/4" drill bit needs resharpening every 8x-10x holes and the 5/8" every 30+.

It is not that our shop isn't experience in Stainless, all we do is mill & turn SS304/316/2205/2507 every single day. But drilling small holes in a pain.
 
The only reason I am actually running this job is because the shop that normally runs them doesnt have tsc on their mill. They were using cobalt and did real well till getting near depth. Then a chip would get under the drill and kill it. Sometime make it 40 holes, sometimes only 5 holes. Lost too many to scrap. Initially I searched high and low for a coolant thru cobalt drill ( or powdered metal ) but couldnt find one long enough. My cycle time is almost indentical to theirs now that I have to peck so often, which sucks. The cobalt drills are like $8 and mine are $125......


Almost always - I am in the conservative camp and would much rather let the machine run longer and keep cheaper tools. Those high $ tools scare me! But on the 310 job I tried to run T/L HSS or Cobalt drills, but they would actually stick/slip in this material / length of tool. You could hear the drills "pop, pop, pop" as they would wind up a bit and then release.

It seems like I had a 5 or maybe even 7 minute drill cycle with the cheaper tools, but even at that - I was OK with it - as long as it would run. Now I was in a lathe, so re-cut wasn't nearly the problem that it is in a vert mill. [regarding pecking] I don't recall why I called Titex, but I must'a been getting failures, as I Shirley didn't order up a $250 drill just b/c of cycle time! (Well, I guess I knew there was no future in the current stick/release program.)

But they set me up with their A6685TFP - 5.5mm drill. Told me the hole prep to use (I mimicked it much cheaper than their recommendation) and told me S/F's and tool life. Like I said - I edited their start hole prep, but otherwise used their numbers, and I popped the hole in one shot in like 30 seconds (less?) and tool life was exactly what they said. It's been a few years since we ran that job, but it seems like it was a $240 drill and lasted about 225-240 holes.

I only broke 1 or 2 of the tools and the rest are able to be sent back for sharpen yet - should we ever get that job back aggin....

I doo have a real HPC pump, but then it's in a lathe too, and I don't know how much juice ever makes it to the tip of such a small tool. I will say that I cannot qualify that juice is actually coming out of the tool at all as there is too much other spray all over and those are such tiny holes, but it obviously worked!


So - when you doo the math with the reduction in cycle time - I came out way ahead, but at a much higher risk too ....

Also - again - I was horizontal, so that aided chip evac a bit. But I was dead tooled, which hurts.... so it could be considered a worsh?


My holes were 3" deep, so I was near 14x deep.



----------------------

Think Snow Eh!
Ox
 








 
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