Haas VF2 Coolant Pump (Pressure) Question ...

[Mike Braddock]

Guys,

We purchased a new VF2 about 8 months ago. It's been working flawlessly for us and I've been very impressed by the factory support. One of the issued I noticed early on is that it takes about 10 seconds for the coolant to quit spraying. Consequently, each time I do a tool change I have to insert a dwell or manually pause the machine to allow adequate time for the pressure to drop (ie bleed off) or else I spray all my toolholder tapers with coolant. Eventually the coolant becomes sticky, causes the tools to start hanging up in the spindle and causes a real problem. Has anyone addressed this issue? I'm planning to add a solenoid valve that turns on when I tool the coolant off to bypass the residual coolant pressure back to the sump. Before doing so I figured I would ask if there is a better solution. Thanks for any advice.

Mike

[lakeside]

are you useing an m-9 before tool change?

[HuFlungDung]

I think the residual coolant is not really under much pressure, it simply is draining to the low point by gravity.

I don't have trouble with coolant making things sticky, really. Do you have a tramp oil skimmer in the sump to remove way lube oil? That tramp oil can add to the stickiness factor.

If you allow the tapers to get a good wash at every tool change, they should never get to the point of being sticky.

[Geof]

You will have the high volume coolant pump on that machine. It pumps at around 20 psi maybe more with the standard coolant nozzles. On the pump is a non-return valve to stop the coolant lines draining back when the pump is off. What happens in the pressure stretches all the plastic pipe between the pump and the nozzles and when the pump shuts off and the non-return valve closes the residual pressure in the system just discharges through the nozzles as the plastic contracts. I have three machines with the same thing.

My solution when I can get around to it is put a low voltage solenoid valve right before the coolant nozzles and wire it to the pump circuit through a transformer so it shuts off the flow as soon as the pump turns off. I plan on using the valves made for irrigation systems and have already tested that the diaphragm in the valve is not affected by my coolant mix.

Hu's point about the tools getting a good wash works okay when the machine is in regular use but things do get sticky when they sit. I have found methyl hydrate (methanol or methyl alcohol) good for getting the sticky off.

[engine tech art]

If you add more coolant nosels it will drian quicker.
What i did is at the end of feed cutting i made my mastercm post spit out a M9 befor i home my y axis for clearance isues with part.
I have 3 nosels and the pcool nosel. It works for me.
Worth a try.

Art

[JPMach]

I had the same problem on my Vf-4. I solved it by putting two larger nozels in the middle two spots and two samll nozels in the outer two spots. I also shortened the middle two about 5 links and added those links to the outer two. Then posistion the outer two as far out as you can while still hitting the coolant where you want it. When the pump shuts off the large nozzels drain quickly and the small nozels are far enough away that as soon as they lose some pressure the stream is no longer in the way of the tool changer cycle. The same happens with the pcool nozzel as it too is far away. The nozels are just standard locline stuff. You can get all sorts of different shapes from enco for next to nothing. Play around a little and you can keep the coolant from getting on the tapers.

I found the best stuff for cleaning tapers and such is carb cleaner in an aeresol can, just watch the paint.

JP

[Mike Braddock]

Thanks for the quick replies guys! I didn't think about the soft lines stretching; that's a good point. I will try some different configurations on the coolant spigots and then I think I will add a valve as you described right before the nozzles. Thanks again.

Mike