deflected nozzles-JV33

[hbb2008]

Anyone know how to fix deflective nozzles? They are causing my darker/grey prints to have lines there for it is not a nice smooth print. Any suggestions?

Im using a Mimaki JV33-6 color,8pass

i have tried bumping it up to 16 pass and it helps with the lines but it changes the print color to much and right now i think i need to try to solve this using 8 pass

I have done nozzle washes at various lengths. manual cleanings under the head with a cleaning swab at very light to zero pressure. my offices is at 50-53% humidity ,72 degrees F

The confusing thing is- when i start my work day, there are no deflections in my test print, but after i print the deflections are there, mostly in the black. If I leave for lunch, they clear up until i start printing again....

The printer is from 2012 and we have replaced the print head 2 times for similar reasons and i cant keep justifying head replacements. The current head is only 3 months old!

Any help is welcomed

 

[WalkerP]

Temp and humidity seem OK.

Have you replaced dampers? I don't think there is damage as you are capable of getting a good nozzle check. Could be a very slight ink demand issue.

It's pretty easy to swap the dampers on top of the heads (swap C and K lines) to see if the issue follows the ink or the heads.

What brand of ink are you using?

 

[hbb2008]

The wiper was replaced in March of this year when the print head was put in, same with all of the dampers. The dampers were going to be my next step. I have someone that comes in every 6 months + to do an overall check and they usually replace the dampers at that time. I am using water based Arcolor inks. We modified the printer to use different inks than Mimamki since we are trying to simulate color matches that we have in our gravure production. So its sometimes hard to get help since we arnt using typical CMYK. we use red, light red, black, light black, blue and yellow-just not in the CMYK hues. Thanks for the suggestion!

 

[brihalter]

When we used the Triangle black we had a similar issue and had to replace the print head after 6 weeks. 2 weeks later the same thing happened. We just plugged in the Mimaki black cartridge back in and that fixed the nozzle. Thus, this saved us from replacing a 2nd print head. So now we use Mimaki black and Triangle for the rest of the colors. Have you tried switching the black back to the Mimaki?

 

[hbb2008]

I haven't tried switching inks, only switching different black formulas made by Arcolor. I currently am not in a position to switch, since my machine is mandated from our headquarters in Germany and our inks match the color of the inks we use in production. Thanks for the tips though!

 

[WalkerP]

OK, I think you misunderstood me. Just for troubleshooting procedure you can swap the dampers on the top of the heads and run a few prints. It will only take an hour or less. If the ink, lines or dampers are the issue the black will continue to band from the C head. If the cyan prints deflect, then it's the head or capping station. I hope that makes sense.
I am not familiar with the ink you are using.

 

[hbb2008]

I think it does make sense. you're saying- switch the black damper with the blue and see if it still deflects in the black. but it the blue starts deflecting it is something with the head or capping station? not the damper? but if the black still deflects its an ink or damper issue?

 

[WalkerP]

Do not remove the dampers from the ink lines. Simply pull the dampers (still attached to ink lines) off the K and C heads and swap them so you're printing C out of the K head and vice versa. Obviously you'll need to do a cleaning or 2 in order to get the ink flowing properly. Then, run your same exact RIPped file, then the nozzle pattern. If the deflection follows the K ink, then it's something in the ink line (damper, line, cart, ink, etc) if the deflection remains in the same head then it's the head itself or the cap/pump.
Essentially all you are doing is eliminating possible variables.

One question, is it the same nozzles deflecting every time or are they moving around in the nozzle pattern?

 

[hbb2008]

Ok this makes sense. thank you! the deflections are in the same area of the test print each time

 

[WalkerP]

Ok, go through the motions to swap dampers/lines and see. Based on my experience if the same nozzles are clogging/deflecting it's likely the head. It could be that the head is not capping up correctly.
If it's determined the head is the issue, the good news is it's not clogged. You may be able to let the head soak with a cleaning fluid overnight to see if that helps. Make sure the pump is in the closed position, fill the capping station up with the fluid and let it sit. I usually will pull the carts out too just in case. I've had the entire carts siphon out into the waste tank before. Not a good surprise in the morning after letting it sit overnight.

 

[SightLine]

This is a tough one.... One of the things that none of us can be sure of is the viscosity of the inks you are using. DX5 heads when used in these machines have their firing voltages set for inks that the machines are designed for which have a very specific viscosity, pigment particle size, and particle density. To the naked eye these would for the most part not even be noticeable to us. You are using inks that are from what I can tell water based and according to the Arcolor website are generally provided as a pigmented powder which is mixed into colors by whoever is using it (this might be done my your headquarters). I'd almost want to suggest contacting your headquarters, explaining what you are seeing, and asking them for suggestions or help. If the viscosity of the ink is very far from what the printer is expecting you can expect problems for sure ranging from clogging, dripping (too low and thin), nozzle deflection, and more.

This is why very few third party inks work very well or only work for a very short time before all sorts of problems. I do think its cool that your company "rolls your own" by doing your own custom ink colors but it does take a lot of technical know how, chemical, and fluid engineering to get it just right. Maybe it settles out of solution some over time, maybe the pigments degrade or break down in some way over time, etc. Its a lot to consider but there are just too many variables to really tell for sure. One way to know for sure would be to flush the machine, install OEM Mimaki inks, and see if the problem goes away. Of course that is not really an option for you so onto other things....

If the capping top is not sealing good that can cause dropouts, deflections, etc as well so that would be another thing to check. Another would be all of the ink line joints to make certain there are no leaks anywhere (they might not leak ink but might draw in tiny amounts of air). The ink system on a JV33 is very very sensitive to the pressures in the ink system which is why open tank style bulk systems generally do not work very well for long on them. Traditional cartridges and sealed ink bag type bulk systems work good because they maintain the pressures that the ink system was designed for. Another might be a sticking cartridge slot valve not opening quite all the way. Enough to let some ink through but restrictive which would cause pressure problems. A lot to think about and chase down but it is what it is.

That being said - I'd love to run a proven 8 color ink set in ours. I realize the print speed would drop in half but if we could have orange, green, violet, red in addition to CMYK you could probably come close to 100% Pantone and to 100% Adobe RGB color gamuts. Of course your RIP would need to understand your ink configuration or at least allow you to create 100% custom profiles that would allow for this.