Mazak QT15 Lube System Issues

My problems started with a slideway alarm which occurred because it was low in oil. I filled it up and was not able to get the alarm to stay cleared. After manual pumping and restarting the machine several times. The machine is a 1988 and is in super nice condition. Still, I figured I maybe should pull the way covers back and look things over.

The Lube MMXL-II pump seemed to be sticking. So I worked on that some and found another on ebay for $60, so I bought that too. I put the ebay pump on since it seemed better. Still, even after quite a bit of pumping the system does not seem to hold pressure. By that I mean I would expect the pump to take a while to discharge the oil into the system. The plunger goes right down in a few seconds. I've traced all the lines and can't see any leaks. My experience has been that the metering units tend to clog up and not pass oil not to open up.

I think my next step will be to take the 3 main lines off at each end point (X, Z, and tailstock) and block them there with some fittings I have and see if it holds pressure with these lines dead headed. Then maybe order all new metering units since that's probably a good thing to replace either way.

Anybody got any other suggestions?

I take the lines loose at the distribution block one at a time, after each lube meter, to make sure I've got a good dripping rate through the meter after manual pumping.

One or more of your meters may be allowing back-flow (or you've got a leak somewhere), thus the system not holding pressure.

If you're getting oil past all the meters at the block, there's good odds you're getting it to the trucks and ballscrews. Check for oil runoff around each truck and the screws, after a lot of manual pumping, you should see it.

If you know you're getting lube to all the points, hot-wire the pressue switch to get going.

ToolCat

Thanks! I was away last week so did not get to mess with it anymore, that and doing a bunch of mill work now.

I was thinking along the same lines. The system really needs a going over so as you say I am just going to check all the lines. I think I will order some metering units first so I have them on hand.

LUBE USA provides oil and grease lubrication systems for leading machine and manufacturing industries around the world, including Single Line Resistance Oil Systems (SLR), Positive Displacement Injection Oil Systems (PDI), Grease Systems, Hybrid Lubrication Systems (LHL), and an array of tubing, fittings and other lube accessories for industrial lubrication systems.

these people are great to work with and can provide all the little widgets for this system
(even if its a bijur pump, which some of these qt15's are. i believe all the little fittings are standard Japanese metric stuff.
or maybe its all bijur standard. who knows. but ive never had trouble sticking Lube parts in all sorts of mazaks,kentucky or japan machines)

if pump is moving oil and handle never gets stiff when working by hand i would look closely for cracked lines or leaks of some sort somewhere

I make sure the pump is primed at it's output. then plug the pump output and lift plunger and release to pressurize. The plunger should NOT go down in a half hour or more. If it does, there are internal leaks in the pump.
I have replaced a pile of pumps over the years.

Bill

yep
me too
if you run them low all the time there's a little brass bushing that wears out and lets the worm and wheel slip

Ok an update....

Machine still torn apart. Mostly doing mill work now so not a huge issue.

This machine is all Lube brand. I had some misc fittings laying around so I took the 3 lines off at the far end (at the manifolds) and blocked them off. Pumped some and indeed no leaks in the main lines. It held fine. So then as CNCToolCat suggested I took all the lines off down stream of the metering units - line by line. After doing the first one (the tail stock) I thought it's just stupid to come this far and not just replace all the metering units on a 30+ year old machine. CNC specialty Store online had the exact Lube parts for about $8.50 or so each. So I have now replaced them all (15 of them) and the lube system is all back together. At least now I know every location should be getting oil. I also replaced the cute little oil filter- $70 of it. So now I need to cover it all up. It really needs new gaskets on the X axis way cover but that's going to have to wait a little.

Thanks for the suggestions!