[Help pls!] Uv printer White INK overspray dust (ink or static issue ?)

[sunereyt]

We're new here so Hello to all !

We're getting crazy to solve an issue we get since some time with the White ink.

I use a small UV flatbed printer and sometimes, the white ink overspray as you can see on the picture.
It is a kind of white dust.

Done already:

- Head cleanings.
- Manual head cleanings.
- Changed ink bottles (ink and printer manufacturers dont find out the issue as well).
- Changed ink channels to see if it comes from printhead.
- Shaked ink (may work a bit but overspray comes back afters 10-15 minutes or 2-3 printings)

After all i have read. I am thinking it may come from electro static issues.

Does anyone already had this kind of problem ?

PS: This happens only with white ink, all other colors prints well.

Have a nice weekend !

 

[seinsig]

White Ink Issues

What kind of print heads are you using? What is the recommended platen gap? It looks like you may be printing too far away from the substrate, do you have access to temperature controls in the head or subtank?

 

[sunereyt]

@seinsig

Hello Seinsig, thanks for your reply !

What kind of print heads are you using?

We are using a Epson R290 Printhead. It is a 6 channels. 2 Channels for white.

What is the recommended platen gap?

Recommended gap is about 2mm but it is manual so we tried to lower the gap as well as put the substrate more far but it is not the issue.
- If we print too far, then the whole image will be blurry.

do you have access to temperature controls in the head or subtank?

The head is temperature is around 22 to 30 C°.
We did not check the ink tanks temperature but we can do it today.

- Is there a recommended temperature ?

About the room humidity, it is about 50%. We just put a humidifier to higher it up and see if it helps.

Also we are changing today the white ink from bottle (with ink tube going straight from it) to an ink tank with blender inside so the white ink should stay homogeneous.

Kr,
Sune

 

[artbot]

i agree. my first impression is close the gap.

 

[seinsig]

White Ink Issues

I don't have experience with that print head, but if you have a clean jet test/nozzle pattern, and you're certain the gap is not the issue, then I would agitate the white ink and increase the tank temperature by a few degrees. I've seen this issue with Ricoh heads when the ink temperature is too low.

 

[sunereyt]

reply

@Artbot

i agree. my first impression is close the gap.

Hello Artbot,
If you mean narrow the gap between printhead and substrate (sorry my bad english ), then it isn't that. We did it already. the only difference would be sharp print or blurry print but the white dust or overspray will stay the same.

@seinsig

then I would agitate the white ink and increase the tank temperature by a few degrees.

I agree,

Today, we changed ink tank to one with a motored blender inside as well as using a new ink bottle inside. For now we have perfect prints. White spray any more.

I've seen this issue with Ricoh heads when the ink temperature is too low

Few weeks ago we had 400 prints to do and had this white issue a lot even as the temperature was very hot. it was more than 35C° in room.

So until now, we think it is (was) ink that is poorly shaked. In consequence, the white ink was becoming heterogeneous.

Also we found out today that some material we are using (Polycarbonate) is very electricity static wish may explain also that dust. For exemple, when is make the substrate wet, it doesnt spray !