Lubrication System Questions on a '98 Daewoo Puma 250B

[smb44]

Hey all,

I just acquired a 1998 Daewoo Puma 250B which has its fair share of issues to address due to its age. I just noticed that it is going through a ton of way lube. It nearly emptied the 0.4L tank in 2 days, say 20 hours of powered on time. It's been idling for much of that as well. I am now E-stopping the machine whenever it's idle to save way lube, which is probably good practice anyway....

I noticed that when manually running the pump to check pressure, it gets to 1.5 MPa (green area on gauge... it's a Vogel pump by the way). When I let go of the manual pushbutton to operate the pump, the pressure immediately drops to zero. I know that on the plunger/bijur pumps, they are supposed to hold pressure for 3 to 10 minutes, but I was wondering if that is the same on this Vogel pump.

So firstly, does this sound like normal operation and lube consumption (the lack of pressure holding after the pump shutting off)? I know old machines like to leak and consume oil, but I am concerned that perhaps a ballscrew or way somewhere isn't getting the lube it needs.

I'm coming with a Haas background and Bijur lube system, which uses wayyyyy less lube (and I thought it was a lot before I got this Daewoo). Box ways are a new thing to me....

Thanks!

 

[wmpy]

I believe those use piston distributors at all the end points. They're supposed to release a certain amount of lube, and then close up. They can fail by getting junk in them and not closing. Once they do that, they just continuously squirt out oil when the pump is making pressure. I would disconnect some of them and see if you can find any that are behaving like that. It would be best to check all of them. If you find any that have failed, just replace them. I have tried to clean them out a few times but have never been successful.

 

[smb44]

I believe those use piston distributors at all the end points. They're supposed to release a certain amount of lube, and then close up. They can fail by getting junk in them and not closing. Once they do that, they just continuously squirt out oil when the pump is making pressure. I would disconnect some of them and see if you can find any that are behaving like that. It would be best to check all of them. If you find any that have failed, just replace them. I have tried to clean them out a few times but have never been successful.

So I assume the pistons are on the sort of manifold-looking blocks on the machine, and not at the connections directly on the guides or ballscrews? And so I understand, what action normally causes them to close up? Fluid amount, pressure, or something else?

Thanks for your help, I really appreciate it!

 

[wmpy]

So I assume the pistons are on the sort of manifold-looking blocks on the machine, and not at the connections directly on the guides or ballscrews? And so I understand, what action normally causes them to close up? Fluid amount, pressure, or something else?

Thanks for your help, I really appreciate it!

Yes, the piston units are in the manifolds. The connections at the lubrication points are just fittings. If one of the piston units is bad in a manifold, you may have to replace the entire manifold. That's just how they're sold. You can't buy the piston units individually.

The pressure causes the piston to move, which forces a small amount of oil out until the piston reaches the end of stroke and closes off the port. When the pump stops and the pressure releases, the piston retracts, and it's ready to cycle again. The volume of oil is determined by the piston unit (also called dester plunger). When replacing, make sure to get the same kind. They're usually stamped on the side.

Please make sure to verify all this. I haven't seen your machine and am not super familiar with Vogel systems. This is just how many systems work.

Another way to check is to remove the coolant tank and put some cardboard on the floor. Turn the machine on, and let it idle for a while. Oil should start dripping onto the cardboard. Try to identify where there seems to be an exorbitant amount of oil coming from. That would be the first place to look for a problem. It could also be just a cracked line or a loose fitting. Usually a broken line won't allow the system to get up to pressure, though.

And yes, draining a lube tank in two days sounds like way too much oil consumption.

 

[smb44]

Yes, the piston units are in the manifolds. The connections at the lubrication points are just fittings. If one of the piston units is bad in a manifold, you may have to replace the entire manifold. That's just how they're sold. You can't buy the piston units individually.

The pressure causes the piston to move, which forces a small amount of oil out until the piston reaches the end of stroke and closes off the port. When the pump stops and the pressure releases, the piston retracts, and it's ready to cycle again. The volume of oil is determined by the piston unit (also called dester plunger). When replacing, make sure to get the same kind. They're usually stamped on the side.

Please make sure to verify all this. I haven't seen your machine and am not super familiar with Vogel systems. This is just how many systems work.

Another way to check is to remove the coolant tank and put some cardboard on the floor. Turn the machine on, and let it idle for a while. Oil should start dripping onto the cardboard. Try to identify where there seems to be an exorbitant amount of oil coming from. That would be the first place to look for a problem. It could also be just a cracked line or a loose fitting. Usually a broken line won't allow the system to get up to pressure, though.

And yes, draining a lube tank in two days sounds like way too much oil consumption.

Awesome, thanks for explaining all of that. I've noticed that it is coming from somewhere on the cross slide, as there is a ton of oil dripping down from it after the pump runs, so that narrows it down to that one distribution block. I'll investigate further tomorrow, and probably order a new block as you suggested if I can determine it's not a broken line.

Good to know that this is excessive oil consumption, otherwise I'd have to accept buying Vactra #2 by the barrel, heh.

Thanks again!

 

[angelw]

Awesome, thanks for explaining all of that. I've noticed that it is coming from somewhere on the cross slide, as there is a ton of oil dripping down from it after the pump runs, so that narrows it down to that one distribution block. I'll investigate further tomorrow, and probably order a new block as you suggested if I can determine it's not a broken line.

Good to know that this is excessive oil consumption, otherwise I'd have to accept buying Vactra #2 by the barrel, heh.

Thanks again!

Hello smb44,
Your description of the manual operation of the pump is normal. In operation, the pump will turn at a preset duration between operations and remain on for a preset duration. When the pump turns on, you will see the pressure build up shown on the gauge and when the pump turns off, the pressure drops to Zero. At each distribution fitting on each of the manifolds there are two, small, spring loaded pistons. I believe they're described as "Insert Tube" and "Sleeve" and are (or at least were) available as a spare part.

The duration between operations of the pump and the duration the pump remains on are controlled by a Timer function in the PMC with the duration of each sequence set in the Diagnostic Parameters. If you have the books for the machine, there should be an explanation of which Diagnostic parameters do what. However, should you not have this information, I suspect that all Puma lathes of that period would use similar Timer Parameters; accordingly, I can look those up tomorrow for you.

If this machine is a recent purchase, it could be that the parameters setting the duration between pump operations and pump on duration could have been changed; I've seen this happen quite frequently. If the duration between pump operations has been set very short, even with the pump on duration set at the factory default, the lubrication reservoir will be emptied in quick time.

Seeing oil emerging from various ares is also quite normal when the pump operates, particularly from the X axis and along the length, at the bottom of the Z axis Slide Way; gravity will ensure that the oil supplied to axes running on a sloping bed will emerge in those areas.

Before you get too involved with the Oil Feed Manifolds, I would check the Oil Pump Timer parameters. From memory, I think the factory default for the duration between pump operations is 15min and pump on duration is 30sec. Even without looking at the Timer Parameters, a physical timing of the operation will give you an idea as to whether the Timer Functions have been changed.

Regards,

Bill

 

[angelw]

Hello smb44,
Before you get too involved with the Oil Feed Manifolds, I would check the Oil Pump Timer parameters. From memory, I think the factory default for the duration between pump operations is 15min and pump on duration is 30sec. Even without looking at the Timer Parameters, a physical timing of the operation will give you an idea as to whether the Timer Functions have been changed.

Hello smb44,
The diagnostic parameters of your machine are likely to be similar to other two axis lathes built around the same time. Accordingly, diagnostic parameters to Lube Pump Time On and Off are as follows:

Lube Pump On = 320 Default setting is 15000 (15 seconds)

Lube Pump Off = 325 Default setting is 900000 (15 minutes)

Regards,

Bill

 

[smb44]

Hello smb44,
The diagnostic parameters of your machine are likely to be similar to other two axis lathes built around the same time. Accordingly, diagnostic parameters to Lube Pump Time On and Off are as follows:

Lube Pump On = 320 Default setting is 15000 (15 seconds)

Lube Pump Off = 325 Default setting is 900000 (15 minutes)

Regards,

Bill

Hi Bill,

Thanks again for your continued help! I've come across countless other threads over the years that you have posted in which have helped me with this machine.

For the oiling issue at hand.... In the manual it states 15 seconds on, and 10 minutes off. I was able to find the settings in the PMC Parameters (Timer table). Oddly enough, the addresses are T00 for the on time, which is at 14976 (equating to 15 seconds), and T02 for the off time, which is set on 600000 (which I also timed at 10 minutes). So, it's safe to assume that these values are in milliseconds unsurprisingly.

While I am tempted to change the oiling off time to 20 minutes, I think the real problem of the distribution blocks needs attention from myself.

-Sean