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Low Pressure Coolant Through Tools?

JBNimble

Plastic
Joined
Mar 17, 2019
I'm setting up my new CNC lathe. I did not invest in high pressure coolant, so I'm limited to about 30 PSI. For all of my external turning and facing, flood coolant will be great. But, is there any value in trying to introduce coolant through boring bars, drills and parting tools with only 30 PSI? Obviously it won't shock the chips or even break through the steam boundary layer, but is the focused flow worth something at least for lubrication and chip flushing? Has anybody done this? Results?
 
I should note, I would run flood also. This is just about creating a small net flow of fluid from the cutting edge out.
 
Sure, I have a standard coolant pump putting coolant to the turret on my Mori Seiki SL-2B and it helps a lot to get some coolant down into bores. I also plumb turret coolant to all of my OD tools. I rarely use the flood nozzle anymore since it is finicky to get located right, and is easily knocked off-location by swarf.

Regards.

Mike
 
Thanks, Mike. If you have all other ports blocked, do you get a decent flood through the small tool ports?
 
Thanks, Mike. If you have all other ports blocked, do you get a decent flood through the small tool ports?

Eh, it's not an inspiring flow, mostly because the fluid distributor inside the turret is badly worn such that all the tools get some flow all the time, instead of the active tool getting all the pressure. Someday I'll make a new distributor.

Regards.

Mike
 
I DO NOT use Indexable Drills without coolant through, whether it be low or high pressure.

The question should be "is it worth the investment in Coolant through tools, if I don't have high pressure?". Because it is never going to hurt.

R
 
I'm setting up my new CNC lathe. I did not invest in high pressure coolant, so I'm limited to about 30 PSI. For all of my external turning and facing, flood coolant will be great. But, is there any value in trying to introduce coolant through boring bars, drills and parting tools with only 30 PSI? Obviously it won't shock the chips or even break through the steam boundary layer, but is the focused flow worth something at least for lubrication and chip flushing? Has anybody done this? Results?

Yes there is a lot of value in that you will be glad to know. Yet if you compare it to high pressure coolant then that will make 30 PSI pale in comparison. The results you can get by focusing the 30 PSI coolant flow will be very much worth the effort.
 
Is it typically OK to add a higher flow and/or higher pressure pump than standard? I'm not talking adding a 1000PSI pump on regular lines, but the pump on my lathe is pretty mediocre and I'm curious if I'd blow the lines apart by going up a pump size or two. Even 100PSI would make a huge difference I suspect.
 
Is it typically OK to add a higher flow and/or higher pressure pump than standard? I'm not talking adding a 1000PSI pump on regular lines, but the pump on my lathe is pretty mediocre and I'm curious if I'd blow the lines apart by going up a pump size or two. Even 100PSI would make a huge difference I suspect.

Moving up in flow capacity probably will not add to your pressure.

Centrifugal pumps up to 275psi and a desirable flow rate are available for relatively reasonable cost without the associated expense of the super filtration that the screw pumps require.

Grundfos and Brinkman both sell excellent pumps for this application.
 
But, is there any value in trying to introduce coolant through boring bars, drills and parting tools with only 30 PSI? Has anybody done this? Results?

I'll put it this way: We bought our first thru-coolant drill several years ago and now I won't buy anything else if I can help it. I've found that ANY amount of coolant you can put at the bottom of a hole helps. It makes plumbing a bit of a hassle (I've gotten pretty good with 1/4" copper pipe) but definitely worth it. I get pretty good flow even through those tiny holes in thru-coolant solid carbide drills.
 
Even a dribble out the tip of a drill helps noticeably!


However, I would recommend an inline sock filter, otherwise you will find out what that .050 allen wrench is for in your Bondhus kit.


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

Think Snow Eh!
Ox
 
I do it on two machines, both with tipped drills and it is a massive improvement from external coolant. You need to rig it up so that you get as little pressure drop as possible.

If at all possible pipe it straight to the back of your tool, in other words don't try to pipe it into the housing and expect it to flow through the tool properly. I learnt the hard way. My seals are messed up and still it works loads better than trying to get coolant into drills externally.

I program a dwell just after the M8 to give it a gap to start pushing through, you need to keep and eye on it as Ox said. Because you don't have high pressure there is a chance that a chip gets stuck on the tools ports but it doesn't happen too often if you program the dwell and take it conservatively.

I need it because I go 2.5-3X D in one shot without any retract. Tool life also improves massively because you are ejecting the chip instead of forcing it back in with external coolant. I could hook up a higher pressure pump but with my seals as they are it probably wouldnt help at all, probably make it worse.
 








 
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