Deep hole drills 30xd

While working up an old process on a new (to us) machine I smoked a brand new 30xD coolant fed carbide drill on it's second hole. I've run these (not quite as deep though) on an Integrex using the manufacturers specs.

The manufacturer recommends around 262 SFM and .010 FPR for both the pilot drill and the 30xD drill. Typically I face the entry flat with a CEM since the holes are all at multiple angles. I pre drill the start hole to 2xD which since I'm using 5/16 drills is .750" deep. Then I switch to the 30xD drill, enter the hole at 1000 RPM with high pressure coolant on at .010 FPR, and go to .011 short of the predrilled hole or .739" deep. Then I pick up the speed to the 3020 (roughly) RPM and feed to depth at the recommended speed. Then I reduce the RPM to 50 RPM and withdraw at 75 IPM out of the hole. ON the Integrex, the spindle has no gearbox so the speed change is instantaneous AND it has spindle speed confirmation so the drill won't feed until the spindle is up to the commanded RPM.

On our Horizontal, the spindle shifts at 2500 RPM, so the spindle stops, changes gears, and then goes to 3000 RPM and feeds into the hole.

I did the first trial hole at 6" deep, and it worked great. The second hole broke the drill about 2 1/2" deep. There was plenty of coolant, so I'm guessing the spindle might not have been up to full speed before the feed rate began. These drills are pretty spendy so I'd prefer not to bust a bunch of them, but they are waaaaaaay faster than peck drilling with a cobalt drill, so it's worth working out the process.

I can see 2 possible solutions, and I'm curious to hear what the deep hole drill experts do.

Option 1 would be to simply add a G4 dwell after the speed change to ensure the spindle is up to speed before feeding in. If I add a 3 - 4 second pause, will it damage the flutes to simply spin .011 off the bottom of the hole? It's a 4 margin KM drill if it matters.

The other option would be to pick up the speed, pause, and start at a slower feed rate, increasing the feed rate as the drill becomes established in the hole.


The material is 4140 prehardened to 32 Rockwell, and I need to go 9.777" deep. I know that's cheating the drill, but the flutes are long enough and I figured I'd go to 9.4", retract almost all the way out of the hole, then feed back in for the last wee bit to make sure the flutes don't plug up.

Curiously,

Stu

I've never used through coolant drills, nor am I a CNC guy, but when drilling those sort of dia / depth ratios, I was taught to centre or spot, use jobber drill to flute depth - 1dia, then a long series to same, and often another say extra long, before bringing out the real long guy to get my final depth.

Also the longer the drill the lower the feed, as in the low end of the manufacturers recommendations.

And above all else peck and clear, peck and clear, (obviously leaving say .5 - 1 x dia still in the hole) constantly;- chips can hang up in flutes and at those sort of dia's it's an instant death play off.

It's worked for me, of course the odd drill breaks, sometimes you need a bit of luck

Stuart Caruk said:

While working up an old process on a new (to us) machine I smoked a brand new 30xD coolant fed carbide drill on it's second hole. I've run these (not quite as deep though) on an Integrex using the manufacturers specs.

The manufacturer recommends around 262 SFM and .010 FPR for both the pilot drill and the 30xD drill. Typically I face the entry flat with a CEM Curiously,

Stu

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TEN THOU PER REV??????????? or is that a TYPO??
The usual Gun Drilling of not so many years ago would of been much closer to 0.001 as in ONE THOU per rev....

Well... maybe the newer carbides and steels for the drills body are that much stronger to absorb the thrust and torque these days??

and 30 times dia is not so much...
how do you think .22 rifles are made 24+ inches long?

and whatz a CEM?

CEM = Center Cutting End Mill would be my guess

Stu, what if you just ran the drill at 2500rpm? It should only add a few seconds to the 20 second drilling cycle, but it might end up the same because the spindle isn't stopping to change gears.

We do alot of these for water lines in our mold inserts although I have not used KM drills only Titex, OSG, and Mitsubishi drills.
I use a macro to do this, but the standard order of events are as follows for the long drills:

1) spindle RPM = 500
2) coolant on I know some manufactures say turn on coolant after in the hole.
3) go to postion X & Y
4) I feed at 40 ipm to about .05-.1 from my pilot drill.
5) turn spindle to correct RPM
6) dwell 1 second this seems to stop the look ahead or at least its waiting for a finish signal.
7) feed at proper feed although sometimes if I am going really deep 30x I will run at 80% of what the manufacture says.
8) at the bottom there is an option to dwell in the macro I have never needed more than 1 second and it does back up .003 before dwelling.
9) I feed out of the hole at 40 ipm I know this is slow but as you said the drills are expensive and sometimes the chips don't flush out and the 2,000 ipm rapids will break the drill on exit I also keep the RPM's up to help keep the chips moving.
10) slow RPM down exit hole completely and on to the next hole.

I hope this helps and good luck.

"The manufacturer recommends around 262 SFM and .010 FPR for both the pilot drill and the 30xD drill."

is that ten thousandths feet per revolution?

Just out of habit I always put a 2 second dwell after I ramp up the RPM...even tho most of our machines are "direct drive" and pretty much ramp up to speed in an instant. 2 seconds is not that much....and if it saves those high $$$ drills, it is well worth it.

Your technique is fine, use the G4 to give the spindle time to get to speed.

What is your coolant pressure and concentration?

.010 is not a typo, that's actually the middle of the road, fairly conservative feedrate @ 262 SFM. I routinely push larger diameter deep hole drills to .017 - .021 feed per rev with no issues. This is of course the first time I tried it on our Kitamura, and I think the issue is the lack of spindle speed confirmation that I was used to on the Integrex. I suspect a dwell will cure the issue after the speed change, I was curious if the dwell in the hole while the spindle ramps up would cause issues, and from private emails from guys who do this a lot apparently it won't.

As far as pecking, the drills are specifically designed to NOT peck. It does take a lot of pressure. I have a wee bit over 900 PSI at the tool tip and lots of fluid coming out of the right consistency. The old school days of peck drilling work fine for short runs of parts, but consider that for 100 parts, the drill cycles are over 13 1/2 hours, vs around an hour and a half. It doesn't take long to justify better tooling. Of course it doesn't hurt as bad to break a long cobalt drill....

Thanks for the tips guys,

Stu

+1 on the straight-through, no-peck points. That's one of the biggest advantages in using a thru-coolant drill.

I see a lot of folks having problems with really deep holes... top of the list is low pressure, but you've certainly got that covered. Filtration and run-out are other biggies, though it really wreaks havoc the smaller the diameter...

Good luck

i believe it is too fast
i would do 200 sfm and feed .005-.007 max
plus stop drill more than .011 before hitting bottom of the holle


remember you are drilling deep hole with expensive drill

IndGild nailed the numbers right on for a Titex bit. seems the factory specs you have may be a little high. Since your pre drilling you do realize the first tool has to have the same tip angle as your long drill or it can chip easily.

I'm using KM drills and they both have the same 140 degree tip. And of course they are running right in the middle of the recommended ranges. The best part of course is the KM guy was here when it happened and he noted that if it broke during testing he would replace it. He's sending in another couple drills to perfect the process. Can't beat that. So far KM has blown away every other drill we've tried. I absolutely love the kentip products. If you've got through spindle coolant, they can't be beat IMHO.

Stuart Caruk said:

I'm using KM drills and they both have the same 140 degree tip. And of course they are running right in the middle of the recommended ranges. The best part of course is the KM guy was here when it happened and he noted that if it broke during testing he would replace it. He's sending in another couple drills to perfect the process. Can't beat that. So far KM has blown away every other drill we've tried. I absolutely love the kentip products. If you've got through spindle coolant, they can't be beat IMHO.

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So were these drills specially designed by KM to break when using their supplied speeds & feeds? Did you mean that KM has blown up every other drill you've tried?

What I don't get is why you are slowing the spindle down as you come out of the hole...? You shouldn't need to ramp up & down the spindle speeds, waiting for the spindle gearbox to shift.

That is the oddest sounding programming I've ever heard of. Who does that? It certainly isn't a common practice at any of the places I've ever worked at or visited. And that includes places that work on hard materials like stainless, 4340, inconel, monel, titanium and ceramics.

When you have a 30xD solid carbide drill buried deep in a hole, it can be carrying quite a bit of chips in the flutes. If the drill is spinning at high speed when you extract it from the hole, it could be so out-of-balance that it could start whipping and break.

I have the Titex "TEC" software, and here's what it gave me:

A6994TFP-5/16 X.treme DH30, EDP#5565036, List $422.00

Run @ 158 sfm (1925 rpm), .0055" per rev., drills 122 blind holes 9.375" deep per sharpening in 53.83 seconds each needing 2.3HP.

Recommended pilot drill is A6181TFT-5/16, run @ 201 sfm (2446 rpm) and .0059" ipr feed. That X-D Pilot drill is a 150º tip, the drills are 140º. Titex prefers a wider angle on the pilot drill than the drill so the tips of the expensive drill have less chance of seeing material before loading the stronger web part.

The preferred cycle for the Titex is use the X-D Pilot to go 1.5xd. Then bring the 30xd drill into the hole at 500rpm (or less) with coolant OFF. Once in, turn on coolant and run it at 25% to 50% of both the recommended speed and feed until it's 3xd deep. Then run at 100% of the suggested rates in one push. At depth, reduce again to 500rpm, turn off coolant and retract.

The software, when I've used it, is spot-on. I have it at only 9.375" deep because you can't get 31.25xd in one shot with a 30xd drill. I believe there would be enough flute to get the depth you need, but I'd clear chips before attempting that last bit. They also have a 180º X-D Pilot drill for the angled entry prep if that's what you need.

The speed of the Kennametal drill really seems awfully high for a pre-heat treated steel. The Titex is more conservative, but you can bump it up if a faster cycle is required and it's working well. You'll get less holes per drill though.

BTW, the Titex X-D Pilot and the DH30 drills are both h7 diameter tolerance. Be careful using a mix of starter drills and deep hole drills because if that pilot drill is undersize to the KM deep hole drill, it can bind and break.

If you have many parts to do, why not run a side-by-side test of the Kennametal vs. a Titex, Guhring, Mitsubishi or OSG long drill? At least Titex gives you exact running parameters for theirs and I know they're willing to bring one or two in for a test against any competitor.

There are certainly lots of ways to skin the cat, with equal results. I typically use Mits and Guhring drills, both with the same technique:

1) Use pilot drill of same diameter; 0-10º wider point angle
2) Pilot to 1.5-3D
3) Enter piloted hole at 60-100 SFM, feed at .010-.012 inch/rev to within .040-.100 of pilot hole bottom
4) Coolant on, spindle speed to drilling SFM
5) Drill hole at corrected SFM and inch/rev (continuous feed)
6) Retract drill to pilot drill end point at 120 inch/min
7) Lower rpm to 60-100 SFM and retract drill from hole at .010-.012 inch/rev with coolant off

As for the speeds and feeds, I'd probably run with 180 sfm, .007 inch/rev, that's pretty much spot-on for Mitsubishi's recommendations. Haven't used the Kenna drills or looked much into them, short of their Y-tech stuff.

All said, I think the consensus here is; slow it down a bit and lower the feed.

I don't do any 30x deep, but I routinely bury 15x deep drills.

I've NEVER been able to achieve the factory parameters on Titex deep TSC drills...I usually make sure the shop is quiet, program at the minimum feed, then turn the feed override to 50%, and listen very carefully while modulating the feed based on sound. At the start, I can usually get to 100% pretty quick, but I have to start dialing back feed as the drill runs deeper. I just write a little subroutine to slow the drill feed based on depth.

Nobody has mentioned drill point angles...but that shouldn't be much of a contributor to the breakage...unless it is walking like crazy. (which it could if the starting drill tip angle is wrong and/or the pilot is oversize)

fpworks said:

I've NEVER been able to achieve the factory parameters on Titex deep TSC drills..

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I've heard reports of people getting bad ruining parameters from Titex tech support, but I've always been able to use the numbers generated by their "TEC + CCS" software at the recommended rates. Where are you getting numbers that don't work?

Nobody has mentioned drill point angles...but that shouldn't be much of a contributor to the breakage..

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This can indeed be a big factor in drill failure. Titex pilot drills are a 150° point and the drills themselves are 140°. This is so the stronger web/point of the drill hits the bottom of the pilot hole first. Other companies use the same angle on both. I don't think there's any solid proof of one being better, but the important thing is to be sure that the tips of the long carbide drill don't hit first, "hog in" and chip.

When using drills and pilot drills from differing sources, the possibility of conflicting diametral tolerances and/or point angle increase right along with drill failure rates.

Thanks Pixman, that's exactly the advice I'm looking for. I'll have to track down a titex rep in the AM.

I broke down and went with some cobalt spade point drills with only 8" of flutes, but long enough to get the job done with a whole lot of pecking. Without coolant it took more than a little while.

As for the KM blowing stuff away, oddly, in several years this is the first KM drill I've blown up.

I think my all time oop, wow was programming an 11/16 Kennametal Kentip drill .15FPR to go 1" deep. Ya, I meant .015 FPR. I was even in single block, but in Mazatrol I didn't get to look at the feedrate in the buffer so the drill comes in, stops just before the part and I hit cycle start. I hear a bam thunk sound and immeddiatly hit feed hold knowing I'd fat fingered something. The tip looked fine and I couldn't quite figure out what the issue was. I looked at the program and noted the error... big oops... then hit reset. It was only when I went to jog the tool back that I noticed the hole was finished. The Bam, thunk was the bit stopping after 1" down and coming back out of the hole. in a fraction of a second. Since the tip was intact I drilled several hundred more holes with it, and I believe it's still going strong. I love Kentip drills.

Assuming they work, they should drill a hole in half the time a titex drill does. Of course I'd rather go slower and not break anything.