Can flood coolant push small tools?

KaiserGlider · May 2, 2021

So a new guy got hired to our shop recently. He has very little experience doing the kind of work we do, so our foreman's been helping him set up parts and getting him up to speed on the stuff he doesn't know. I check on the new guy from time to time to keep an eye on him, answer questions, etc. Anyway, the other day he was drilling a part with a .086 drill (held in a drill chuck). I noticed he had turned down the coolant pressure and pointed the nozzle away from the drill so the coolant was just pooling on top of the part. He told me the foreman had checked his setup and told him to do that because the coolant would "push" the drill and reduce runout. We both thought this was odd, but the foreman has decades of experience on both of us. So we kinda just shrugged and went about our business that day.

I'm curious though. Is one of us a moron? We're not talking high-pressure or through-spindle coolant here, just Haas VF2 flood coolant. There were 4 nozzles turned on, so all the pressure was not just concentrated through one or two. I've always had the Haas programmable coolant nozzle pointed at the tip of whatever tool was being used, since, as I understand it, the purpose of coolant is not just to cool the tool but to wash chips out of the way too. Surely a .086 drill is sturdy enough to withstand this kind of pressure. And if runout was that big of a concern, then surely he would have held the drill in a collet instead of a drill chuck anyway.

Would excessive coolant pressure actually be something to avoid when using a micro tool, say .01 diameter or smaller?

ButtonPusher · May 2, 2021

No Morons

KaiserGlider said:
So a new guy got hired to our shop recently. He has very little experience doing the kind of work we do, so our foreman's been helping him set up parts and getting him up to speed on the stuff he doesn't know. I check on the new guy from time to time to keep an eye on him, answer questions, etc. Anyway, the other day he was drilling a part with a .086 drill (held in a drill chuck). I noticed he had turned down the coolant pressure and pointed the nozzle away from the drill so the coolant was just pooling on top of the part. He told me the foreman had checked his setup and told him to do that because the coolant would "push" the drill and reduce runout. We both thought this was odd, but the foreman has decades of experience on both of us. So we kinda just shrugged and went about our business that day.

I'm curious though. Is one of us a moron? We're not talking high-pressure or through-spindle coolant here, just Haas VF2 flood coolant. There were 4 nozzles turned on, so all the pressure was not just concentrated through one or two. I've always had the Haas programmable coolant nozzle pointed at the tip of whatever tool was being used, since, as I understand it, the purpose of coolant is not just to cool the tool but to wash chips out of the way too. Surely a .086 drill is sturdy enough to withstand this kind of pressure. And if runout was that big of a concern, then surely he would have held the drill in a collet instead of a drill chuck anyway.

Would excessive coolant pressure actually be something to avoid when using a micro tool, say .01 diameter or smaller?

i have noticed runout with jobbers but only with smaller drills,( maybe .040?) as well as extra long, like 12-16x diamater. If the foreman said that there is probably a reason.

I have coworkers who would rather hand tap 40 m2’s/2-56’s and smaller because of “that one job 30 years ago that he scrapped lots $$& of parts due to a junked small tap.

If the drill is getting enough coolant to stay sharp and clear chips, no harm done.

ButtonPusher · May 2, 2021

After reading it again about pooling and no direct coolant, sounds like the same coworker I am talking about, (as well as the reason our spot drills and drills have never come out of his machine sharp).

Orange Vise · May 2, 2021

No.

Force = Pressure x Area

Force is proportional to the size of the drill. Small drill = small area = small force.

Long drills might be a different story, but that has nothing to do with the diameter of the drill.

mhajicek · May 2, 2021

Aircraft length? Maybe, if you're trying to hold tenths on position and not using a spot drill, but then you should be using a stub pilot anyway. Jobber length? Not a chance. HSS or cobalt with a spot, or solid carbide (no spot needed) the coolant force will have zero measurable effect on the position of the hole. More coolant is better to get the chips out.

Did they indicate the drill in to less than a tenth? If not he's just blowing smoke.

CarbideBob · May 2, 2021

The only thing I can think of is that too much direct coolant flow does not allow the small sized chips to come out of the hole easily, loading the drill.
In some more rare cases I'd have to disagree that more coolant pushed in up top helps gets the chips out.
Bob

Milland · May 2, 2021

Orange Vise said:
No.

Force = Pressure x Area

Force is proportional to the size of the drill. Small drill = small area = small force.

Long drills might be a different story, but that has nothing to do with the diameter of the drill.

Hiya Orange,
I think there's a little more too it than that. We're dealing with a single supported beam under bending, which has a faster response to changes in the ratio of diameter to length as the diameter gets smaller.

So for small HSS drills (under .016" or so?) in jobber length I could see some deviation from regular coolant flow pressures. But realistically it's unlikely with drills as large at .040"/1mm unless as suggested it's an aircraft length.

What can also set up issues is if the drill tip isn't ground correctly, and one flute produces larger chips over the other. Then, the combination of extra surface area for a swinging chip (before separation), the change in CG due to the mass of the chip on one side only, and even chance of a vibration resonance setting up oscillation of the drill - if things work against you, you could have excessive movement of the drill tip, even enough to bang on the side of the work rather than follow the hole if pecking.

There's a lot of worst-case going on above, but it's non-zero. However, per the OP's description it does seem like it's much ado about nothing. An .086" drill isn't going to notice a ~60psi coolant stream.

triumph406 · May 2, 2021

It would take about 5 minutes to check.

Put an indicator (somebody else's not your own) in a plastic bag, make sure it's sealed, mount the tip of the indicator against the tip of the drill and turn the coolant on. You'll see straight away if there's any deflection.

evega · May 2, 2021

I don't see much issue with coolant effecting drills and my shop runs small stuff routinely. 0-80, 2-56 and 4-40 are normal. The smallest hole are .04 or so and those are fine too (for stub length drills). We may run the pressure below full blast on some machines but not by much.
I'd say it depends a lot on the job and shop in general. Machining and programming is all about matching the machine, tooling, material type and programming style to get a final product.

To each his own so let the chips fly !

TeachMePlease · May 3, 2021

I can run an .017" endmill with 1000psi coolant directly at the tip, and make a hexalobe with +/-.0005" tolerances....

So I doubt that flood coolant is going to push an .086" drill.

boosted · May 3, 2021

KaiserGlider said:
he was drilling a part with a .086 drill (held in a drill chuck)

It always fascinates me that some people will work their problems small-to-big. I would have a LONG list of things to check (starting with that drill chuck) before I decided the coolant pressure might be causing runout

Tom Lg · May 3, 2021

I routinely use a 0,27mm (0.0106") drill with about .250" flute length drilling to 1mm depth in a Swiss mill/turn and I have the oil aimed right at the tool. Lots of oil. It's like several small garden hoses going on it at once. I meet my tight location specs and get hundreds of holes per drill. Hundreds. Of. Holes.

CORONA VIRUS · May 3, 2021

KaiserGlider said:
I'm curious though. Is one of us a moron?

Being that you are from California I would bet both of you are morons. But, to answer the question, yes. Coolant can bend a drill, and if using high psi, can break it.

Speedie · May 5, 2021

Orange Vise said:
No.

Force = Pressure x Area

Force is proportional to the size of the drill. Small drill = small area = small force.

Long drills might be a different story, but that has nothing to do with the diameter of the drill.

Ha you contradicted yourself with a right answer and ended with a incorrect relation. This is me on a weekend...especially when questioned

Mike1974 · May 5, 2021

CORONA VIRUS said:
Being that you are from California I would bet both of you are morons. But, to answer the question, yes. Coolant can bend a drill, and if using high psi, can break it.

Evidence!? We use a .01" @ 50x diameter, drilling from both sides and have the holes lined up well enough to thread .008" wire so I call BS unless you are running a .005" drill ay 5000psi or something.

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