Head strikes while printing with HP Latex 800W

[StickerGuy83]

I'm noticing markings of what appears to be mild head strikes that run vertically through the print, but only on one side, and about 10-12 inches inward from the edge (your left if your standing in front of the printer).
Its intermittent throughout 100 ft roll, but this has never happened before and nothing has changed as far as materials, ICC profiles etc. Material stays quite flat from what I can see.

I've done the following but it has not corrected anything.

Cleaned printheads
Aligned printheads
increased vacuum to about double what the ICC profile setting was
Installed the edge guards
Always using the take up and always calibrate the take up tension prior to printing

Has anyone experienced this? I've printed a lot prior to even having this issue, and it has never done this before.

 

[balstestrat]

Issue with bad roll?

 

[StickerGuy83]

I don't think its the material. This has happened on the last 4 rolls. Different lot #'s.

 

[balstestrat]

Okay, let's see a picture of it?

 

[StickerGuy83]

Okay, let's see a picture of it?

 

[balstestrat]

It's catching inside top of the heater.
Lower your heat or airflow.
You might even want to lower your vacuum. Change it to 10 if it's SAV.

 

[StickerGuy83]

It's catching inside top of the heater.
Lower your heat or airflow.
You might even want to lower your vacuum. Change it to 10 if it's SAV.

There is no ink on the heater. From watching it, the take up is not tight like the previous models, it almost has a "flop" as it is advanced. And it is also only hitting on the left side when the carriage is traveling back toward the maint cartridge. This to me, seems that the carriage is traveling too fast and catching that end of the material as it is "flopping" after the material advances. I added a 550ms interpass delay. So far so good. Running a full roll now.

 

[balstestrat]

Yeah it's supposed to be like that, tighten and release. In the next firmware you can change it to keep tight all the time. There is also special profile with that enabled already in use if you need it. That would probably help that as well.

In that picture is the carriage moving left to right? So print direction is up down?

If you lift up the heater and go behind the printer. In the slot that the paper enters there is the first top metal part, kind of before the heaters, there is no ink at all?

 

[StickerGuy83]

The roll just finished printing. I will check those areas of the curing zone for any ink. But From the markings, it appears the material is gently tapping the printheads, only at the left side of the print (if your standing in front of the printer). I'm running 54" wide rolls.

Printing is bi directional, so it starts from the right side (maint cartridge side), travels left, delays for 550ms, then travels back to the right and delays 550ms. This seems to be working. No markings that i can see.

In theory, if you look at the area where its hitting, its only on the left side of the print, and only within about 10 inches from the edge. Never affected any other areas. So that faint fraction of a second, its catching the print head slightly as the carriage is traveling back. The interpass delay would eliminate that hitting IF that is what is causing it.

I'm getting rid of this printer hopefully in the next couple weeks. Print quality isn't exactly what I thought it would be with the smaller picolitre droplets. Still too big and still grainy. Colors are more vibrant though.
Waiting for the s80600L and Laminator.

 

[balstestrat]

Alright, I'm surprised you didn't notice that in the samples. To me the graininess seems pretty much the same as previous gen. Its not really everything about the drop size, there is more to it than just that.

 

[StickerGuy83]

I think the droplet size not being variable and limited to 10pl is the main cause for the graininess. I mean don't get me wrong, you can print acceptable prints with it, but when your printing small graphics that have a lot of detail within a 3-4" space, your end result will be far from the result of a printer that is capable of printing with variable droplet sizes that can go as small as 4-5pl. If HP were to make the switch to a piezo head with variable droplet sizes that small, they would be way ahead in the market. Latex printheads are the most important part of printing, but their weakest link. These printers are great for things viewed from farther away. Banners, wallpapers, signage etc. Decals/Stickers .... not so much.

I've had this printer for a very short period of time now, and have had 5 bad printheads already. This to me is not only unacceptable, but an annoyance. Between complaints from customers to down time waiting for replacement printheads, this is a road I don't wish to travel moving forward.

 

[Mike Perth]

It's catching inside top of the heater.
Lower your heat or airflow.
You might even want to lower your vacuum. Change it to 10 if it's SAV.

This is correct, we’ve seen this on our 800w with SAV. If it was the heads the marks would have a horizontal smudge. The media is definitely hitting the heater. We’ve had our 7 months and have only changed out one head so far.

 

[balstestrat]

I think the droplet size not being variable and limited to 10pl is the main cause for the graininess. I mean don't get me wrong, you can print acceptable prints with it, but when your printing small graphics that have a lot of detail within a 3-4" space, your end result will be far from the result of a printer that is capable of printing with variable droplet sizes that can go as small as 4-5pl. If HP were to make the switch to a piezo head with variable droplet sizes that small, they would be way ahead in the market. Latex printheads are the most important part of printing, but their weakest link. These printers are great for things viewed from farther away. Banners, wallpapers, signage etc. Decals/Stickers .... not so much.

I've had this printer for a very short period of time now, and have had 5 bad printheads already. This to me is not only unacceptable, but an annoyance. Between complaints from customers to down time waiting for replacement printheads, this is a road I don't wish to travel moving forward.

You have to also remember there is massive difference with eco-solvent and water-based ink. You can have 80% of water on the ink you lay down on a print that will be evaporated off.
Anyway I agree with you eco-solvent with good piezo head is better, I'm just not so sure that would be the absolute case with latex ink.

I would actually love to see how the Epson R5000 performs with small stickers and difficult colours. It has piezo head so there should be great difference then.
yannb could post some pictures to me, I would appreciate.

 

[yannb]

You have to also remember there is massive difference with eco-solvent and water-based ink. You can have 80% of water on the ink you lay down on a print that will be evaporated off.
Anyway I agree with you eco-solvent with good piezo head is better, I'm just not so sure that would be the absolute case with latex ink.

I would actually love to see how the Epson R5000 performs with small stickers and difficult colours. It has piezo head so there should be great difference then.
yannb could post some pictures to me, I would appreciate.

Hi, I will be able to post some pictures from R5000 prints in about one or two weeks when I’m back in our demo room. Prints are less grainy than HP L570, but more than SC-S80600. I haven’t seen small prints from a new HP latex.

 

[Joe House]

Between complaints from customers to down time waiting for replacement printheads

This is kind of a mixed blessing. They will fail more frequently, but you can replace them yourself and they cost 1/10 or less of a piezo head.
I encourage all of my customers to keep at least one of each head on hand so there is no wait for a new head. If it's under warranty, HP will replace it, but if you're calling at the end of the day, it can be 2 days before it arrives. It's about controlling what you can control.

Good Luck

 

[StickerGuy83]

This is kind of a mixed blessing. They will fail more frequently, but you can replace them yourself and they cost 1/10 or less of a piezo head.
I encourage all of my customers to keep at least one of each head on hand so there is no wait for a new head. If it's under warranty, HP will replace it, but if you're calling at the end of the day, it can be 2 days before it arrives. It's about controlling what you can control.

Good Luck

I totaled up what I've spent on HP Latex printheads over one year with only normal replacement (at around 2000ml) and this is based off of only one printer.

I've spent $4000 on Latex printheads from June of 2020 to June of 2021. This does not include any printheads that were warranty replacements.
It is roughly around $5000 to replace all of the printheads in an s80600 with installation from a technician.
The life expectancy of the Epson heads, in a high volume shop, from what I was told, will be 4-5 years.
I take estimations like these with a grain of salt. Realistically, I would say 3-4 years which is not far off.
But lets say its 3 years.

Latex heads over 3 years will total around $12000 based off of a previous year replacing them at around 2000ml.
Epson heads with installation, roughly $5000.

I would spend way more money on Latex printheads over the long run than I would replacing the Epson heads with a tech installing them.
Most HP Latex users will say "I get 4000-5000 ml out of my printheads". That is just not realistic in my opinion. I can see distinct color shifts around the 2000ml mark.
Print quality is also reduced due to wear on the nozzles. They're thermal, they heat up, they cool down. That process deforms the nozzles which will affect print quality to
a noticeable extent, as well as color inconsistency over time. Printing full rolls at a time helped with them lasting longer, but if your doing peace meal jobs or very short runs
frequently, where the printheads heat up and cool down often, this will shorten the lifespan of the printheads.

This might be okay for shops that print wraps or wallpapers, but repeatability in color is just not consistent after that point. Also with the latex, I would have to print status plots
and occasionally perform printhead cleanings before every roll to confirm that I'm not losing a significant amount of nozzles.

All of this information is from actual real world experience running these latex printers. All in a 24/7 climate controlled ventilated area with little to no dust (no windows).

 

[balstestrat]

Most HP Latex users will say "I get 4000-5000 ml out of my printheads".

I have to say I'm on this train but everyone to their own. Average to my eyes from many many printers seems to fall between 5000-10000ml.
Some peeps who print very little may get less but they have already had the heads in use for a year or two.
Then there are the big shops who just push out stuff and the quality isn't n1, can go up to 20000ml or so.
On the big latex it has the same die in the head but 5 dies combined. I've seen heads with over 100 000ml of use. That's 20000ml per die.

Also with the latex, I would have to print status plots and occasionally perform printhead cleanings before every roll to confirm that I'm not losing a significant amount of nozzles.

This I can't really understand why. It's like the opposite of the usual, you shouldn't need to print the nozzle test almost ever.
If you keep using the printer every day it shouldn't lose nozzles daily, like there is an issue or something else wrong if that keeps happening with new printheads.


Maybe it really is just the wrong equipment for your application?

 

[StickerGuy83]

Update:

Found the cross cutter laying just inside of the curing zone. Not sure how it detached from whatever propels it, but it was definitely laying on its side. I'm running some jobs through it now and I did notice it no longer flops up and down when the take up is doing its catch and release. I'm thinking when the material was loaded, it just fed over it and was not laying perfectly flat. I'm curious to see if this will correct the issue.

 

[P Wagner]

Update:

Found the cross cutter laying just inside of the curing zone. Not sure how it detached from whatever propels it, but it was definitely laying on its side. I'm running some jobs through it now and I did notice it no longer flops up and down when the take up is doing its catch and release. I'm thinking when the material was loaded, it just fed over it and was not laying perfectly flat. I'm curious to see if this will correct the issue.

The X-cutter should be physically attached to the carriage - can you take a pic of it and post?

 

[StickerGuy83]

The X-cutter should be physically attached to the carriage - can you take a pic of it and post?

On the 800W it is no longer mounted to the carriage from what I was told. When I took delivery of this machine it was just kind of sitting there on a track where it felt floppy and loose. I was told that is how it is. It functioned fine as well up until the other day. Attempted to cross cut the roll and it did not even score it. It also did not sound like it normally does when you cross cut. I'm thinking all of these problems i've been having are related. The cross cutter is sitting on the desk now. I'm not even going to attempt to put it back in. If all the issues go away I think its safe to assume that there is some sort of flaw in the new design/operation of the cross cutter.