DMG Mori NLX 2500 700 SY spindle brake and chuck problem

byazici · Feb 19, 2020

Hello,

Need some help on this one as it has become very confusing...

A little background on the machine...So, the machine is practically new as it is situated in a university R&D lab, it has about 300 hours on it, but its 2.5 years old. Its used as a research machine however, we do warm-up cycles on it every other day so it stays in good shape. When we bought the machine, in 2017, the manual of that time (before the celos 4.0 manuals) said the hydraulic and cooling oil needed to be changed every 2000 hours of machine use. The techs did not tell us that "machine use" means as long as the machine back panel switch is ON. Anyway, we didnt change the oil for a long time and some problems started appearing.

The first problem was that the turret was giving an indexing fault. We called the techs, they came in and told us that the weight distribution on the turret wasnt even so it was giving an error. They removed some tools, looked at the selenoids, did some thugging on the turret and it started working. So, they left and the next day the second spindle chuck open/close system locked up and both of the spindle brakes locked-up. I tried to find some answers and realized that in the Celos 4.0 manuals, the maintenance booklet was changed and now it stated that both the oils need to be changed every 2000 hours regardless of the machine being ON or OFF. So, I figured might as well change the oils and the filters, so I did. Thats all fine, however, the spindle brakes are still clamped and the second spindle does not open/close. I checked the selonoid switches, they work but, the selenoid valves themselves do not seem to move even though they are energized.

Now, is this problem caused because of a late oil change, or am I looking at the wrong place and its caused by something completely different? Any help would be appreciated. Thanks.

cameraman · Feb 20, 2020

byazici said:
Hello,

Need some help on this one as it has become very confusing...

A little background on the machine...So, the machine is practically new as it is situated in a university R&D lab, it has about 300 hours on it, but its 2.5 years old. Its used as a research machine however, we do warm-up cycles on it every other day so it stays in good shape. When we bought the machine, in 2017, the manual of that time (before the celos 4.0 manuals) said the hydraulic and cooling oil needed to be changed every 2000 hours of machine use. The techs did not tell us that "machine use" means as long as the machine back panel switch is ON. Anyway, we didnt change the oil for a long time and some problems started appearing.

The first problem was that the turret was giving an indexing fault. We called the techs, they came in and told us that the weight distribution on the turret wasnt even so it was giving an error. They removed some tools, looked at the selenoids, did some thugging on the turret and it started working. So, they left and the next day the second spindle chuck open/close system locked up and both of the spindle brakes locked-up. I tried to find some answers and realized that in the Celos 4.0 manuals, the maintenance booklet was changed and now it stated that both the oils need to be changed every 2000 hours regardless of the machine being ON or OFF. So, I figured might as well change the oils and the filters, so I did. Thats all fine, however, the spindle brakes are still clamped and the second spindle does not open/close. I checked the selonoid switches, they work but, the selenoid valves themselves do not seem to move even though they are energized.

Now, is this problem caused because of a late oil change, or am I looking at the wrong place and its caused by something completely different? Any help would be appreciated. Thanks.

You might want to re-post this in the main CNC section to get some more eyeballs on this.

If you have a schematic of your hydraulic systems and pneumatic systems that might be helpful.

There may be a master valve (higher up the hydraulic chain) for those circuits somewhere.

When you say oil do you mean hydraulic fluid or is it a different lubrication system ?

I've always had an interest / fixin' to pull trigger on NLX 2500|500 and one day perhaps an NLX 2500|1250 (simple two axis) ~ So I'm kinda interested in NLX type problems or potential issues.

I believe there are at least 3 PM members that have bought NLX type machines in the past two years.

2000 hours ??? Seems like maybe a bad translation maybe ? change fluids every 83 days (just because the machine is powered up to the wall) ? (I certainly hope not ! :-) ).

I wonder if the techs closed a valve and forgot to open it again , seeing the design of the valve bodies and types of spools, spring returns and hydraulic circuits might be illuminating perhaps ???

The hydraulic unit / pump and related systems are supposed to be fairly accessible ~ But your machine is quite new and maybe not one you want to tear into yourself (Not sure what your tech and warranty situation is ? Can you call the techs back ?)

Good to know the solenoids and relays seems to work.

byazici · Feb 21, 2020

Problem solved.

So, here is what you do if you get a turret index error, C axis brake not engaging/is stuck or your spindle clamps are not working:

Taking into consideration that the problem is not electrical, its most likely hydraulic. What happens is, when the hydraulic oil gets older, its starts leaving a residue on everything it passes through. This includes your hoses, the gauges, the valves and the ports. Most of the time this residue will not affect the way things function, however, when it comes to valves, this is not the case.

The firts thing to do is check the selenoids attached to the hydraulic valves. There are a total of seven selenoids. Three of them are on the back side of the machine, behind the sheet metal, just above the coolant oil tank. These are the turret clamp/unclamp and the C axis brakes for both spindles. The other four are one the front bottom left corner of the machines, behind the spindle clamp force gauges. These are spindle 1 open/close and spindle 2 open/ close.

The first thing to do is take out the selenoid and measure for resistance. They are 24V selenoids. If you have a measurement, get a portable multimeter, adjust for DC voltage and stick the prongs into the contacts of the selenoid you took out. Activate the function that you are having problem with and see if you are getting +/-24V on the multimeter. If No, your problem is in the electrical cabinet. If yes, your problem in the hydraulic valves. If electrical, you need to check the relevant relay-LED-resistor combo that is on the pcb for each selenoid. This is shown in the electrical schematics file that came with you machine and you are done here. If hydraulic valve, continue on.

The hydraulic valves are very precisely machined devices. They have micron level tolerences that allows the pistons to move inside the valve chambers. This piston movement enables them to open/close or move from one side to the other for certain activations. The afore mentioned devices, on the NLX, work with these hydraulic valves and if the valve pistons are covered with the residue from the hydraulic oil, they get stuck and the 40bar pressure of the NLX is not enough to engage them. So, you need to clean them. There are very good videos on Youtube explaning this procedure, its not exactly the same valve setup, but very similar. I will link one below.

YouTube

The piston might not come out easy. Brake cleaner fluid helps, make sure you take out all the o-rings beforehand. Give it a good clean, especially the outside of the piston and inside of the valve chamber, the seats. Brush it with brass or plastic brush using kerosene. Afterwards, dont rinse, just blow air and it will evaporate.

Put it back together gently, its hardened steel, but if piston or valve seats are damaged, its gone.

Side note: if you are doing this for the chuck clamps, you need to bleed out all the previous hydraulic fluid, as there will be old fluid left in the hoses. Doing this is tough, let me know if you need help on this.

Good luck.

cameraman · Feb 21, 2020

byazici said:
Problem solved.

So, here is what you do if you get a turret index error, C axis brake not engaging/is stuck or your spindle clamps are not working:

Taking into consideration that the problem is not electrical, its most likely hydraulic. What happens is, when the hydraulic oil gets older, its starts leaving a residue on everything it passes through. This includes your hoses, the gauges, the valves and the ports. Most of the time this residue will not affect the way things function, however, when it comes to valves, this is not the case.

The firts thing to do is check the selenoids attached to the hydraulic valves. There are a total of seven selenoids. Three of them are on the back side of the machine, behind the sheet metal, just above the coolant oil tank. These are the turret clamp/unclamp and the C axis brakes for both spindles. The other four are one the front bottom left corner of the machines, behind the spindle clamp force gauges. These are spindle 1 open/close and spindle 2 open/ close.

The first thing to do is take out the selenoid and measure for resistance. They are 24V selenoids. If you have a measurement, get a portable multimeter, adjust for DC voltage and stick the prongs into the contacts of the selenoid you took out. Activate the function that you are having problem with and see if you are getting +/-24V on the multimeter. If No, your problem is in the electrical cabinet. If yes, your problem in the hydraulic valves. If electrical, you need to check the relevant relay-LED-resistor combo that is on the pcb for each selenoid. This is shown in the electrical schematics file that came with you machine and you are done here. If hydraulic valve, continue on.

The hydraulic valves are very precisely machined devices. They have micron level tolerences that allows the pistons to move inside the valve chambers. This piston movement enables them to open/close or move from one side to the other for certain activations. The afore mentioned devices, on the NLX, work with these hydraulic valves and if the valve pistons are covered with the residue from the hydraulic oil, they get stuck and the 40bar pressure of the NLX is not enough to engage them. So, you need to clean them. There are very good videos on Youtube explaning this procedure, its not exactly the same valve setup, but very similar. I will link one below.

YouTube

The piston might not come out easy. Brake cleaner fluid helps, make sure you take out all the o-rings beforehand. Give it a good clean, especially the outside of the piston and inside of the valve chamber, the seats. Brush it with brass or plastic brush using kerosene. Afterwards, dont rinse, just blow air and it will evaporate.

Put it back together gently, its hardened steel, but if piston or valve seats are damaged, its gone.

Side note: if you are doing this for the chuck clamps, you need to bleed out all the previous hydraulic fluid, as there will be old fluid left in the hoses. Doing this is tough, let me know if you need help on this.

Good luck.

Nice ! Good write up too.

Recently I had to doooo "Tractor surgery" on my front end loader on my tractor … In the end only replacing spring return detents and other assemblies. But in a very tricky place so had to pull the whole column and associated hydraulics for the control lever etc. and drag it into the kitchen for a few days lol.

I was telling everybody to be really nice to the tractor so a $300 repair does not become a $2000.00 repair.

Those 4 or 5 way valve bodies with multiple spools, as you say (@byazici) are incredibly close fitting. (spools to the valve body). The parts and service folks were telling me that the spools are fitted to the valve bodies so if a spool gets "Knackered" you have to order new valve body with spools (your "Pistons") as they are allegedly fitted to each other ? I.e. NOT interchangeable parts (at least not on Kubota tractors lol).

I'm familiar with hydraulics used in aviation, less so with tractors, back hoes , bull dozers etc. ~ But they were saying the valve body is $1400 to $2000.

That then got me thinking as "Valve bodies" of all different types are one of the classically marketed types of part that can be done on 5 axis machines ? Then got me thinking about what ARE the tolerances for these valve bodies and is it true they don't use interchangeable parts and are the spools really fitted and graded to each valve body ?

Then that got me thinking did Byazici eventually score a 5 axis machine for his design department. Did Dr. Mori give him the "Nod" ? (Not that most university departments don't deserve a free/ subsidized 5 axis machine.).

Also got me thinking ~ Does DMG Mori "Sting you" for doing your own work on a relatively new machine ? Mazak can get a little tricky with that / void warranty ?

@Byazici how long do you think the hydraulic systems were standing for ? ~ Curious as to what hydraulic fluid they are using ? Is it something very environmentally friendly hence it seems to "gel" harden and almost cross link ? versus a less environmentally friendly counterpart ?

@Byazici thanks for sharing ! Glad you were able to get into the machine and really sort it out. :cool:

byazici · Feb 21, 2020

Hey Cameraman,

The hydraulic fluid gets pretty old pretty quickly actually, especially the one that they put new at the factory, which was the one we just took out of the machine. The machined was used for about 400 hours in machining, but it had worked for about 2000 hours on idle and sat for about 6600 hours when the machine was shut off. As far as my newly acquired knowledge tells me, hydraulic fluid ages much quicker if it's under pressure, and still ages if it's sitting. So, 2000 hours of pump time is the recommended time for changing the oil, even if the machine is idle; that means the machine control is turned off, but the machine hydraulic pump and the electricals have power.

Thanks for the nice words. Mr.Mori did not offer a free machine, but a very nicely priced one was on the table. Another development happened and we got a crazy price from Mikron (maybe they are reading these threads after all). It was definitely more expensive than the DMU 50, but it was critical decision for us as the DMU 50 lacked some of the feature we wanted. In the end, we decided we could not give up on the crash protection system of the GF Mikron Mill P 800 and that was more important for us. So, we have a Mikron sitting at the prototype lab right now. Here is a pic:

cameraman · Feb 21, 2020

byazici said:
Hey Cameraman,

The hydraulic fluid gets pretty old pretty quickly actually, especially the one that they put new at the factory, which was the one we just took out of the machine. The machined was used for about 400 hours in machining, but it had worked for about 2000 hours on idle and sat for about 6600 hours when the machine was shut off. As far as my newly acquired knowledge tells me, hydraulic fluid ages much quicker if it's under pressure, and still ages if it's sitting. So, 2000 hours of pump time is the recommended time for changing the oil, even if the machine is idle; that means the machine control is turned off, but the machine hydraulic pump and the electricals have power.

Thanks for the nice words. Mr.Mori did not offer a free machine, but a very nicely priced one was on the table. Another development happened and we got a crazy price from Mikron (maybe they are reading these threads after all). It was definitely more expensive than the DMU 50, but it was critical decision for us as the DMU 50 lacked some of the feature we wanted. In the end, we decided we could not give up on the crash protection system of the GF Mikron Mill P 800 and that was more important for us. So, we have a Mikron sitting at the prototype lab right now. Here is a pic:

View attachment 279623

That's beautiful , I remember you were very keen on the Mikron and the fairly unique crash protection capability* seems pretty important especially in a more academic environment.

With the synthetic granite base + Heidenhain control + DD (drives) tandem you get everything you want. I remember you said that the machinist that recommended that machine passed on / died, and budget wise was difficult to close the gap on that. very mold capable (5 axis) and machine parts and pretty much anything else.

Nice Mikron / GF etc. were able to give you an academic discount and then some.

Sounds like that worked out very well indeed. :cool:

_____________________________________________________________________________________________

* Cheap to crash even for an expensive machine !

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