Question Direct Print to Aluminum

[SignsWizard]

Hey y'all,

As the title suggests, I'm attempting to print directly to bare aluminum, using a UV flatbed printer (Vanguard VK300D to be exact). Besides one test, all of my test prints have failed, with the paint easily cracking off and peeling from the substrate after taking a blade to the print.

For more context, I'm printing a white base layer followed by color graphics, and I'm using AP3155 to prep the surface before printing. I've tried a wide variety of different application methods with the adhesion promoter, with nothing giving me a strong result. My gut is telling me that I might be missing something involving the printer itself, like messing with speed and going from bi-directional to uni, or even changing how many passes I'm taking. Right now I'm running these tests under the same setting I use for coro and ACM, and while my UV lamps set high.

I also have hunch that the white ink itself may be the issue here, given it's already finicky nature, I can see the white ink having an even harder time adhering to an already difficult surface. But I've had tests fail with and without the white base layer, albeit my only successful print has been without. The specific test the worked was a 3:1 IPA spray that was wiped off and then allowed to sit 24 hrs before I printed graphics with no white layer.

For the sake of covering bases:
-The substrate is cleaned with 99 IPA before any chemicals applied, and the 5052 aluminum I'm using came vinyled from manufacturer
-I've tried applying AP3155 with a saturated white microfiber, as well as mixing the AP3155 3:1 with IPA and 1:1 with Acetone and spraying those mixtures on
-I've tried wiping the AP3155 off after application using white microfiber, as well as not wiping after applying
-I've tried printing directly after applying, as well as having pieces set for intervals of 30 mins/4 hrs/24 hrs

Any thoughts on where I might be going wrong? Apologies if I'm all over the place!

 

[petepaz]

a few things but #1 if you take a blade to any sign or print it's going to scratch it. noting is impervious to blades other than metal photo process.
the true test is the tape test. print a sample and put a piece of tape on it rub it down real good and pull the tape see if any ink comes off.
we sometimes will put some slices in the sample print so the edge is exposed then do the tape test and if it holds up you have a winner.
also there are different types of UV ink and some are more aggressive on things like acryilic or plastics and some are better on metals so if you plan on doing the mjority of printing on metal then you may want to do some more research on what inks you have and what's available for your printer.
we print on aluminum all the time, raw, anodized, painted and we really don't have any issues. we have a roland LEJ, EFI and fuji acuity the roland seems to stick the best then the efi and the least on the acuity.
we really just prep/clean it with iso alcohol and away we go.
you could try upping the passes with your lamp and get more curing time

 

[SignsWizard]

Just to clarify, when I take a blade to the print, I'm referring to doing a tape test of sorts. I cut a cross hatch pattern and look for paint chips to come off, and then apply tape to further investigate if the ink held on. I think I'm also doing something similar to what you described, where I leave part of the substrate exposed.

Examining ink I'm using itself is a good idea, albeit from my novice stand point, I only see one paint being sold for my printer - but I have a feeling that's not something that's actually set in stone and the only product I could be using.

I will definitely trying upping the amount of passes I do and see if that nets me any results. It makes me hopeful to hear that others have plenty of luck with aluminum substrate.

Thank you, Pete!

 

[signheremd]

You say the Aluminum came Vinyled from the Manufacturer... so there is a coating on the aluminum? If so, you might want to try AP2155 instead of the AP3155 - it is better for plastics, PVC, HDPE...

The brittle nature of the cured UV inks also suggests the lamps are too high (the ink is more flexible with less lamp and more brittle with more).

It sounds like you are getting the oils off. When we have a piece of metal that we need to get all the oils off, we use Greased Lightning from Lowes (a bleach/detergent blend) for the first cleaning, followed by Windex and alcohol for the second. Last cleaning is a prep like AP3155 or Solv S1000.

 

[SignsWizard]

No coating, just a vinyl applied to protect the aluminum - the vinyl comes off easily and doesn't seem to leave any residue. Between using IPA and applying AP3155 I would have to think it sufficiently clean of any residue.

I'll try going the opposite direction with the UV lamps, I was totally under the impression that higher = better adhesion.

Thank you for the advice, I will give what you've said a shot!

 

[Gino]

Sounds like you're using the wrong profiles.

 

[SignsWizard]

Big noobie question - aren't profiles based on the color output/color management? I've thought about how the profile might be the issue, which is why I stated that I'm using settings based on coro/ACM production, but from my unlearned perspective, I'm not sure how the color management might be affecting my results here.

 

[cstone94]

Just curious, what’re you trying to achieve by doing this?

 

[Gino]

Nope.

 

[SignsWizard]

The project is for retail, in which the pieces will act as a cover plate over food dispensers that customers interact with. The signs will be installed on an all-aluminum fixture, and from what I'm imagining, the customer wants the banding around the print to match, compared to the black from an ACM core. I'm not the guy calling the shots on the project, but if I were, I think I'd be outsourcing this to a silk screen process or making a stronger argument towards using a different substrate.
Hopefully that gives you a better insight into what the goal is, and why I may be setting unrealistic expectations for myself when it comes to print wear-ability.

To give an update, I fudged around with the number print passes and UV intensity, and still had the same results as before. While I think the results I'm getting might actually be passable for many cases, the fact that a good gouge in the paint can take lead to a cascade effect due to chipping, and the fact that these will be used by the general public, means that I'm no where near comfortable putting my name/my employers name on these. If I had to wager, as Pete mentioned, ink might be the culprit here - the printer manufacture only sells this one specific ink for this printer, and I'm not sure my employer would be open to testing out different inks, given we would have to waste the ink we already have running, and potential for further failure.. : (

If this issue is with printing profiles, like I said, I'm really quite in the dark in that area. I gave ICC Frequently asked questions a good glance and while I my eyes may have started to glaze over a bit, I didn't catch anything that stood out towards the issues I'm having. I did some YouTubing on the subject as well, and it all came down to advice on print appearance, not ink adhesion itself. I can make wild assumptions as to how the profile might change my outcome, like, if the profile controls the amount of ink being put down, then maybe I'm using too much - but my logic says that if the initial layer of ink has the chance to adhere, then it will do so, and the layers of ink that follow should be able to bind to that just as strongly.

Lots of shooting in the dark here on my part, and I really appreciate everyone's responses to my problem.