White Ink Dripping / Pooling after purge

[smholm22]

Hey y'all. I've been having varying degrees of white ink issues on my OCE 360 for months, and wondering if anyone has any insight. The main symptom we see regularly is : white ink dripping from the heads in the morning. This is sometimes a weekly problem, and sometimes a daily problem. A service tech came out a month or so ago and increased our meniscus slightly, along with checking the integrity of it. We ran good for a week after that, and then the white ink was dripping again. Whether or not what he did was any real help is hard to say, as we would often go a week without issue anyways.

What I've been doing is, purge the white until I get the ink level to low, bleed the filter, and generally we're good for a little bit after that.

Most of the time when I purge the white heads, after I suction the ink off, white ink continues to 'leak' out of the white heads and pool along them. This behavior typically stops after I do the full 4-5 purges and bleed the filter, and then begins again after I discover the white heads had been dripping.

Yesterday, for the first time, I was hardly able to purge the white heads at all. Initiating the first purge resulted in no visible drainage. The second and third purges resulted in a little bit. After changing the meniscus filters, it was purging as usual again. Additionally, I discovered that the white ink in our nozzle checks was about half as saturated as usual, and then returned to the density I expect to see after changing the filters.

I've replaced the meniscus micron filters multiple times while we've been experiencing this and that typically alleviates the issue slightly, but never for long and never completely.

It's also worth noting that we had to fully replace our IGUS half a year ago after a break in our white ink line caused white ink to get on the rest of the lines. The technician did a thorough job of cleaning and replacing the IGUS.

I have a call in with my technician who thinks it's an issue of air in the lines, subsequently causing ink in the micron filters, repeatedly.

Does anyone have any other theories, or anything to add to my technician's theory? What could be causing this to happen so so often? I've been running this machine for 4 years and only recently began seeing these persistent issues.

 

[AlsEU]

Check the ink pouch inlet, I saw situations, when the old inlet was sucking the air around the ink connector. Check also the recirculation valve, maybe it is not closing completely. Of course, check all the fast connectors along with the white ink tubing (between ink port and ink manifold).

 

[smholm22]

A few weeks back we had a technician come out and replace the ink pouch inlet, along with the white degas module. He verified our meniscus was where it needs to be, also, and checked our ink connections. I don't know if he checked the recirculation valve or not.

It seemed like things had improved briefly, but I think was delusional about that, and we're still facing the same issues.

Some things I've observed since then...

- Our white ink nozzles appear to be firing 'good,' but when compared against nozzle tests from a while back, they're certainly significantly less saturated (see image of nozzle test swatches)
- Anytime we replace our white ink meniscus filter, within a week it will have white ink in it

I've also attached an image of what our white-ink banding looks like when printed over. The disc shows a current print, with White-White-Color. The 6x6 square is an approved sample from months ago when we weren't experiencing these issues.

 

[AlsEU]

The technician verified the meniscus vacuum with the external gauge?
Anyway - if you have ink in the meniscus vacuum filter only in one channel, seems that you have a problem in that specific channel, between the ink manifold (meniscus vacuum is separated into channels there) and the printheads. Have you checked the ink level sensor? Is it clean? Maybe it is stuck sometimes and then ink flows into the vacuum tubing reaching the filter. You can also swap sensors between two channels and check if the problem stays in the white channel (not a sensor problem) or moves to another one (faulty sensor). It's also possible that the electronic board, where sensors are connected, is damaged.

 

[edcooleyar]

I believe most degas units have been long removed. Is your tech a canon/oce guy or dealer?

Second, is the meniscus filter getting filled with ink? It’s only a failsafe and there are other problems if this is happening.

Third, check the ink tube labels on all the white connections. Our installer reversed the recirc line on the whites and all kinds of weird s**t was happening. Could easily happen with the igus track replacement. Takes a while for the ink to work it’s way into the filters and muck up the works.

Is the vacuum 11.5” and vary less than .1 inHG on the ink screen? How often does the vacuum pump kick on?

Could be a leak in the resevoir, the vauum line or even the printhead. When the symptoms occur, is the reservoir showing low?

Swap the meniscus line with another channel and see if it follows it. Sometimes it’s as easy as clipping the end of the vacuum tube to get a better grip.

 

[smholm22]

Thank you both for replying -- I'll try to answer these to the best of my ability. I've been running this machine for almost 4 years. Me and my supervisor (who operated the machine before me) do perform a fair amount of maintenance and service ourselves, but it's limited to what we've previously observed a technician do.

Our tech is a canon/oce guy. We've actually had two different techs come out and look at this, both through a Canon service call.

Yes, both techs verified the meniscus vacuum with the external gauge. The reading from our console and from the gauge were practically identical.

I haven't checked the ink level sensor. This is my first time hearing about that part, but after looking up and seeing the part online (3010105624) I'm fairly confident I recognize it, there's a row of them and they sit vertically above the print heads, yea? Is it difficult to check if they're clean? Does swapping them require any special procedures?

The meniscus filter does get ink in it. Being the white channel, it's difficult to determine how much ink exactly is getting into the filter but it's easy to spot it on the inlet tube of the filter. I replaced the filter yesterday and this morning the inlet tube of the meniscus filter already has obvious signs of white ink in it.

When you ask "Is the vacuum 11.5" and vary less than .1inHG on the ink screen?" I'm assuming you're talking about "Meniscus vacuum (in H20)" -- if so, it generally sits at 12.5 and will vary by +- .3 During one of the tech visits, they did increase that slightly as an attempt to fix our problem with the white ink dripping overnight. I believe it had been sitting around 11.4-11.8 previously. These problems existed before and after they made the change.

The vacuum pump seems to kick on every 2 minutes and 4 seconds, I just timed four cycles with my stopwatch.

The reservoir does not show "Low" when the symptoms occur. However that reminds me of something I noticed, which may be completely normal but seemed potentially atypical with my limited knowledge -- when I come in in the morning, usually my ink reservoirs all show "Full." After I perform a long purge at the maintenance drawer, CMYK will all show as "Low," but the White channel will often require two more long purges for it to read as "Low"

I've never swapped a meniscus line and am unsure how to do so, though I think I can imagine the process... does that require any special procedures or considerations?

A few additional observations I've made in the past day --

Along with the obvious difference in nozzle checks in the photo I shared above, I ran a print that we had delivered to a client a couple years back that shows a 100% -> 0% white ink gradient, along with large swatches showing every 10% decrease in saturation alongside the gradient. We still had a copy of our sample from then, and comparing the old one against the new one shows an obvious ~30% decrease in overall saturation, especially in the areas that should have the most saturation (70-100%)

There is a fairly substantial kink in my yellow ink line just before it attaches to the degas module. This doesn't look ideal, but also seems irrelevant to our problems being that it's the yellow ink line and we don't seem to have any issues with our yellow ink. Regardless, I've attached a photo.

While the technician did replace our white ink coupler, where the white ink bag attaches, it does still feel quite loose compared to the other couplers.

Again, thank you both for your time so far.

 

[smholm22]

Update : We shutdown the machine, clipped that yellow ink line, and re-attached so it's no longer kinked. Upon restarting the machine I ran a purge and vacuumed the heads, resulting in a Low status for all channels. It now seems that the white ink pump is no longer running. I can't hear it, and the white ink status is staying at Low. I've reseated the white ink bag, closed/opened the maintenance drawer a couple of times, and tried to run a nozzle check all in an effort to kick it into gear. I restarted the machine again and still sign of the white ink pump running. Gosh, this is fun.

Edit : I saw in someones old post that when their white ink pump failed, it didn't completely "die," and they could get it to turn over by 'tapping' it. Can anyone guide me on where the ink pump is located?

 

[AlsEU]

Ink pumps are located in the box between the ink pouches - the white ink pumps is easily recognisable, as it's the only one with the recirculation valve in the ink tubing, all other channels are straight - ink pouch-tubing-pump-tubing-carriage.
If you want to clean the ink level sensor, you need to follow this sequence:
- close all valves on the top of the carriage except the cleaned channel
- do the purge twice (remove the ink from the subtank of the cleaned channel and only from this channel)
- close the valve in the cleaned channel
- disconnect the ink pouch in the cleaned channel
- switch off the printer
- remove the sensor in the cleaned channel with the Allen key
- clean it with the IPA (the plastic part on the metal shaft should be moving freely))
- reinstall the sensor (be careful about the rubber o-ring, it's important)
- connect the ink pouch
- switch on the printer
The printer should refill the white tank to the 'full' status. Usually, after some time ink sediments on the metal shaft of the level sensor interferes with the sensor movements. You can also swap the sensors between two channels to check if the sensor works properly.

 

[edcooleyar]

The reason I asked if it was a Canon tech was because there has been a mandatory upgrade in place for a while to get rid of the degas units. They make little difference in a properly functioning printer. No new machines have them.

I’ve attached a photo of ink pumps that are going bad. They often have a small amount if black dust under them and will have to be replaced soon. They can be very loud when running as well - another clue it’s time to retire them.

It’s normal for some white ink to drip onto the spit tray overnight. If it’s puddling it means there is a vacuum leak someplace or your printhead are damaged. From your description, it sounds like ink drops are on the printhead in the morning which would indicate a loss of meniscus vacuum or leaky printhead.

Your vacuum pump should not be running every 2 or 3 minutes so it appears you also have a vacuum leak. Most likely related.

Your meniscus is too high as well which may be contributing to your problem. According to the specifications your vacuum should be 11.5 inH2O plus/minus .1 inH2O. (My bad on the inHG). I’ve included a photo of the ink bay with the vacuum pressure relief valve which I’m told you can use to adjust your vacuum. Meniscus vacuum is a balance: too little and it drips more ink than it should. Too much and it will suck ink out of the printhead causing nozzle outs.

If ink is being sucked out of the reservior into the meniscus vacuum tube it will eventually clog the ptfe filter and dump your white ink. Bad enough and your white ink gets drained into the spit tray. Could be the high vacuum, bad reservoir, reversed ink lines, bad printhead even.

It sounds like you may have discovered some of the problem since your ink pump has totally quit. Seems you may have several issues converging with that ink channel.

 

[AlsEU]

If the meniscus vacuum would be too high, ink in other channels would be sucked into the vacuum filters first (before white), as white is the heaviest ink. Playing with the vacuum valve without having the external gauge connected to the vacuum system may cause more problems - inks sucked into all vacuum filters and therefore more issues.

 

[edcooleyar]

As long as the vacuum dac is calibrated, you have a manometer built in. If the white ink is saturating the meniscus vacuum filter you’ve got serious problems already. Most likely not related to the vacuum being higher than spec.