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Anti-foam agent for oil ?
- Thread starter cuslog
- Start date
Current (and most problematic) hole is 0.212" dia. Depth is 136 X dia. Single flute carbide drill. Drill stem is hollow, pressurized oil pushed down middle, out the cutter, then back up and out via a deep crease in the tube, chips separated in a chip box, filters etc. Shop built / cobbled together mostly from parts on hand, scrounged etc.
Is the issue that your 'recirculation' oil is somewhat foamy as it enters the tooling & causing issues? Or the oil is fine (foam free) going in but its foaming around the business end of the tool as its spraying from the tiny ports? I've been exposed to this in a completely different discipline & it can get complicated in a hurry.
I don't get to see the oil on the intake side but I do see it on the exit - my chip box has a plexiglass top. At the start of the hole it's foam free but it soon starts to change color and look a bit "foamey". It takes ~ an hour to drill to depth. At full depth, its quite foamey and HOT. My reservoir is ~10 gallons -- I have thought that my reservoir may be too small. Pump is a hydraulic pump, to clear chips, I need pressure at ~ 1200 PSI. Larger dia. holes (.450") ~ 400 psi will clear chips and there's not so much foam, nor as much heat.
It can get complicated in a hurry & a lot of industrial applications spend big money on what amounts to educated guesses & witchcraft chemistry. The presence of water can significantly reduce surface tension, making it more susceptible to foaming. Some detergents, or the wrong surfactants, or the right surfactant but wrong temperature band, can reduce oil surface tension and increase foaming. Visualizing the application at those pressures I'm guessing a big factor is turbulence related - flowing through & exiting from a small opening (spraying). Sudden pressure change is kind of related. Oxidized or degraded oil. Filtration issues. On & on. I've seen videos of oil going through a conventional auto style gear pump with looser tolerances or higher temp & its bizarre, dark 'fluid' oil on the inlet, tan color shaving cream on the discharge. Maybe this & other reasons why CNC applications are water based emulsions? (probably a science in itself). Probably not helping you much, but good luck.
Ooops. Previously I was not on the right page, not even the same book or even in the same library.
So from a guy with less than zero experience in drilling these types of small and deep holes - here’s my thoughts - maybe the issue is that in either hole diameter (0.450 or 0.212”) the chips are about the same size. In the larger hole the annulus allows the chips to be evacuated but in the smaller hole the chips are too big and require more pressure to be evacuated plus are causing the heating and foaming. Just my 2 cents worth from far left field.
So from a guy with less than zero experience in drilling these types of small and deep holes - here’s my thoughts - maybe the issue is that in either hole diameter (0.450 or 0.212”) the chips are about the same size. In the larger hole the annulus allows the chips to be evacuated but in the smaller hole the chips are too big and require more pressure to be evacuated plus are causing the heating and foaming. Just my 2 cents worth from far left field.
As @PeterT states: complicated. I believe in your case with the small drill, the point where the oil exits acts like a “homogenizer”: it literally tears the oil molecules apart and in the presence of air, the solution reforms with air molecules trapped in it (the foamy, milky appearance).
You don’t have the problem with the bigger drill, because the pressure differential is not as great and thus less of a “homogenizing” action is taking place.
I am not sure there is actually anything to worry about if the cut / bore quality is still as desired and your drill bit lasts (it gets well lubricated, the chips clear) and the air comes out of solution (de-foams the oil) before it gets pumped again (so the pump is not cavitating).
I wonder if a drill with more flute clearance (bigger flute(s)) would reduce the foaming as the chips would have more room to evacuate and thus you could run your system at a lower pressure?
Probably not practical, but: drill vertically up. You’d have gravity on your side to help with chip evacuation. Josh Topper recently did a video why he likes to use the horizontal mill (using the horizontal spindle) for long key ways -> chip evacuation.
You don’t have the problem with the bigger drill, because the pressure differential is not as great and thus less of a “homogenizing” action is taking place.
I am not sure there is actually anything to worry about if the cut / bore quality is still as desired and your drill bit lasts (it gets well lubricated, the chips clear) and the air comes out of solution (de-foams the oil) before it gets pumped again (so the pump is not cavitating).
I wonder if a drill with more flute clearance (bigger flute(s)) would reduce the foaming as the chips would have more room to evacuate and thus you could run your system at a lower pressure?
Probably not practical, but: drill vertically up. You’d have gravity on your side to help with chip evacuation. Josh Topper recently did a video why he likes to use the horizontal mill (using the horizontal spindle) for long key ways -> chip evacuation.
Is there a reduction in penetration rate as the hole progresses - could be because of: increased oil heat; chips binding in the hole; or not enough time for air to be released from the oil. Maybe the oil needs more retention time in the tank (or bigger tank for air to separate and time to cool). Does the tank have a baffle? (first in - last out).
Hole quality looks OK, after drilling 28.5" deep hole, tool is still sharp. Oil temp and the foam give me some heartburn though.
Tool is power fed just like power feed on a lathe. Work piece spun @ 2000 ~ 2500 RPM, feed @ ~ .0002 per rev.
Couple pics attached of deep hole drill and my setup. Deep hole drills are quite a bit different from a standard twist drill .. only one flute, point is off-center by 25% of diameter which leaves a peak in the center of the workpiece, helping to keep it centered. Current piece I drilled, exit hole was .016" TIR @ 28.5" depth. I have gotten as good as .001" TIR at the same depth but that's not every time.
Fuchs GD-1 is the oil I have (not the anti-foam version).
Going to check my filters -- 3 stage filtering system. 1 is coarse pad like a Scotch brite pad, 2 is a cylindrical wire screen at the outlet of the tank and 3 is a spin on hydraulic filter. (Filters may be getting plugged).
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I had that problem with a large hydraulic oil reservoir. Apparently the tank was underfilled so when the oil flowed back in the tank it created a whirling action that broke the surface of the oil and caused it to bubble/foam just like the white water in river rapids. I filled the tank and left it for a couple of days. Problem solved. The foam, in my case, drastically reduced the psi and rendered the machine useless. Also the more foam, the more heat I got
Yes, makes sense.
I can't help but think I just need a bigger tank / reservoir. I have a friend that has a Pratt & Whitney deep hole drill (Industrial / production model), his tank is 45 gallons, he has no heat or foam problems. Trouble is; a 45 gallon drum of that oil is $$ -- but foam in the oil = not good.
I can't help but think I just need a bigger tank / reservoir. I have a friend that has a Pratt & Whitney deep hole drill (Industrial / production model), his tank is 45 gallons, he has no heat or foam problems. Trouble is; a 45 gallon drum of that oil is $$ -- but foam in the oil = not good.
So at that hole depth and rpm a hole takes about 60 minutes. How about (to evaluate if a bigger tank is needed) simulate a larger tank by intermittent drilling-
drill for 20 minutes;
stop for 20 minutes;
drill for 20 minutes;
stop for 20 minutes;
then complete the hole.
Also - you didn’t say whether or not the tank has a baffle - IMO a baffle or 2 could make a big difference.
You could also monitor oil temperatures start to finish when drilling continuously vs the proposed intermittent method.
Without the expense of a heat exchanger, a simple fan blowing on the tank will help quite a bit.
Before switching to the GD7043 oil, ask the manufacturer if the 2 oils (GD-1 and GD7043 can be mixed. Also ask if they have an anti foam cocktail you could add.
If you do think a larger tank is the answer- get a second tank the same as the first and put them in tandem with a coil of copper pipe connecting them.
drill for 20 minutes;
stop for 20 minutes;
drill for 20 minutes;
stop for 20 minutes;
then complete the hole.
Also - you didn’t say whether or not the tank has a baffle - IMO a baffle or 2 could make a big difference.
You could also monitor oil temperatures start to finish when drilling continuously vs the proposed intermittent method.
Without the expense of a heat exchanger, a simple fan blowing on the tank will help quite a bit.
Before switching to the GD7043 oil, ask the manufacturer if the 2 oils (GD-1 and GD7043 can be mixed. Also ask if they have an anti foam cocktail you could add.
If you do think a larger tank is the answer- get a second tank the same as the first and put them in tandem with a coil of copper pipe connecting them.
Thanks for your responses and suggestions.
I hesitate to start / stop for fear of affecting the accuracy of the hole but I do see your reasoning - might be worth trying, even if I do lose a piece of material.
Baffle, no there's not one. Made my own tank, didn't think of it at the time but did since and again, see your reasoning.
2nd tank, yes, I like that idea.
Fan, like that idea too (cheap).
In the meantime, I've pulled the screen out of the tank and cut open the spin-on hyd. filter. The spin on, the paper element was coated with very fine "fines", so replaced that.
Don't have time to try it today, maybe after the long weekend.
Forget to comment - IMO that is great accuracy results and even more amazing when coming from a home made drill. Well done!
PS - I used custom drill accessories to improve the accuracy of deep straight holes (3” diameter x 80’ deep in rock). Regardless of size or methodology each deep straight hole has its own challenges.
Over heating of oil is a fairly common problem, the basics seem to always come to the surface, or the lack of. Over working a given amount of oil is a very big one, and makes for heat in a system, hoses/lines too small, sharp turns, 90degree elbows, any resistance/restrictions, plugged filters/screens. One not often thought about is changing a steel line for a flexable line, the extra layers act like insulation, slowing heat transfer. Small return lines, small suction inlet lines to pumps also cause numerous problems as well.
I do understand the need of pressure to remove chips and to provide cooling/lube to the drill face and drill shaft, in hand with flexing supply lines to allow movement of material and/or drill bit. It appears the answer is cooling and more oil capacity, is there a way to put a fan blowing on what appears to be a catchment bin and maybe fans blowing on oil tank and supply lines to drill bit? A way to increase capacity of oil, an aluminum tank with fins on it and a fan blowing on that? It may not take a large increase, a few gallons would make a difference.
I would think higher pressure is needed with the smaller bit, which makes for more foam to deal with which could mean a defoaming/ settleing tank with some baffles to slow oil movement down allowing air release.
A friend was having problems with surging and some foam. The addishion of a 20lb propane tank solved that. Extra tank allowed oil a place to quickly return to and a bit more time to "degas", before returning to supply tank.
Yes, it was an old tank with no propane in it!!
I do understand the need of pressure to remove chips and to provide cooling/lube to the drill face and drill shaft, in hand with flexing supply lines to allow movement of material and/or drill bit. It appears the answer is cooling and more oil capacity, is there a way to put a fan blowing on what appears to be a catchment bin and maybe fans blowing on oil tank and supply lines to drill bit? A way to increase capacity of oil, an aluminum tank with fins on it and a fan blowing on that? It may not take a large increase, a few gallons would make a difference.
I would think higher pressure is needed with the smaller bit, which makes for more foam to deal with which could mean a defoaming/ settleing tank with some baffles to slow oil movement down allowing air release.
A friend was having problems with surging and some foam. The addishion of a 20lb propane tank solved that. Extra tank allowed oil a place to quickly return to and a bit more time to "degas", before returning to supply tank.
Yes, it was an old tank with no propane in it!!
historicalarms
Ultra Member
awesome topic Cuslog It was my dream to build the same outfit you did but I got way-layed somewhere along the way.
Somewhere i still have the "guru of home built barrel making machines" tape from Bill Web. That tape came with a thick folder of printed specs that he had observed to work. Long time since I read them but from memory I will say he used a 5 gallon pail as his reservoir( with an overflow divider in it to separate chip oil from delivery oil) and drilled at 700 psi oil pressure (he used a common power steering pump from a car) but reduced the pressure to 300 for finish-reaming.
I would try the suggestion of stopping periodical if it alleviates your issues as the finish ream should clean up any stop caused abnormalities.
There is a barrel maker in Red Deer name of Bob Jury that, when I talked to him he had one machine similar to yours and was building another at the time. Bob is very easy to talk to and may have some real life experience that may help you out.
Somewhere i still have the "guru of home built barrel making machines" tape from Bill Web. That tape came with a thick folder of printed specs that he had observed to work. Long time since I read them but from memory I will say he used a 5 gallon pail as his reservoir( with an overflow divider in it to separate chip oil from delivery oil) and drilled at 700 psi oil pressure (he used a common power steering pump from a car) but reduced the pressure to 300 for finish-reaming.
I would try the suggestion of stopping periodical if it alleviates your issues as the finish ream should clean up any stop caused abnormalities.
There is a barrel maker in Red Deer name of Bob Jury that, when I talked to him he had one machine similar to yours and was building another at the time. Bob is very easy to talk to and may have some real life experience that may help you out.
Thanks for your response.
As of today, I've removed the spin on filter, cut it apart and spread out the paper guts -- quite a lot of "fines" trapped in the paper. Spun on a new filter, soon, I'll try it again.
I like the fan idea, just don't have one to put on it at the moment, have to pick one up somewhere.
For awhile now, I've been daydreaming about more oil capacity / designing a new tank in my head -- tank itself isn't the biggest problem with that, its the cost of the additional oil. The oil I'd like to get is only sold by the 45 gal drum at about $3000 per drum -- and this is just a hobby for me !