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Direct Print to Acrylic - Volume

Discussion in 'Digital Printing' started by sbergman, Mar 26, 2020.

  1. sbergman

    sbergman Premium Subscriber

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    Sep 13, 2012
    Paterson, NJ
    We won a job to print 230+ unique images on acrylic ranging from 20"x20" up to 40"x60". We are planning to direct print 2nd surface with white ink on 51"x100"x0.25" acrylic sheets and then cut on our CNC.

    Our software/equipment:
    RIP: Caldera V13.1
    printer: HP FB550
    Router: Multicam 5000 with camera
    Laminator: GFP 463TH

    We have done some a couple of tests, but would like to hear any best practices or workflow tips that might save us some headaches related to:

    1) Do you cut blanks and then print to them versus nesting on 51x100 sheet?
    2) What diameter bit do you use to cut the acrylic? Do you return for a 2nd pass to finish or just one pass?
    3) Do you used a diamond bit to polish the edges of the acrylic or use another method?
    4) Do you use a backer? What type? When during the process do you apply it? We used to skip the white ink and use white a vinyl backer prior to CNC'ing, but we had complaints from customers about vinly lifting on edges and pulling the ink right off with it. Do you have a better process with vinyl?
    5) How do you store the pieces after they have been printed/cut before packing/wrapping them, since they are so fragile?
    6) For any newbies reading this, our first tests routing 2nd surface printed acrylic did not go so well, because we had placed the acrylic directly on the MDF spoil board of the CNC which seems to have caused a lot of scrapes and damage to the image/ink. Now we are using mats from X-edge (MatriX Mat) and that seems to have solved our "ink scrape issues".
     
  2. rossmosh

    rossmosh Active Member

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    I'd process the blanks and then print. Printing and then finishing is an absolutely terrible idea.

    As for the edge finish, that's a matter of opinion and customer's tolerance. Some will accept a router edge. Some will accept a sanded edge. Some only want a polished edge. If they want a polished edge, I'd call around to acrylic specialists and find out how much they would charge to put on the provided acrylic. I'd specify you do not want flame polished.

    If you want to keep things in house, I'd try to go from the router right to the buffing wheel. Then clean and print.
     
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  3. Bobby H

    Bobby H Very Active Member

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    It's better to print directly on flat acrylic using a flatbed printer after the parts have been routed. If you try printing direct on a large sheet and then routing afterward you run into two possible problems. First, the material registration on the routing bed compared to how it was originally set up on the flatbed printing bed has to be dead-on. Otherwise there will be alignment problems, big or small. Then the routing process may chip away parts of the print job along the edges of the material. Even the slightest bit of flaking along the edges can ruin the job. I think it's better to cut the parts first, position them precisely on the flatbed printing surface and then print direct to the material.
     
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  4. sbergman

    sbergman Premium Subscriber

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    Sep 13, 2012
    Paterson, NJ
    Thanks for the feedback. You have convinced me that I should at least attempt to cut the blanks on the CNC before printing. I'll run some some tests this afternoon. On the plus side I expect way improved yield from my acrylic, because Caldera wasn't doing the most efficient job nesting the 230 images. On the minus side it will be a lot more labor to load 230 pieces of acrylic versus (88) full sheets.

    Assuming we print on the pre-cut blanks and we need to printing edge-to-edge are there any tips/tricks to keeps our belt from becoming completely ink ridden (HP FB550-hybrid UV flatbed)? I am estimating we will need no make the image 1/8" larger than the acrylic to ensure full coverage. We had tossed around the idea of apply a 1.5" wide blue tape to the front of the acrylic with some overhang to "catch" the extra ink, but this seems time consuming. Attached is a picture. Any best known practices?

    Is it the norm to apply a backer to protect the image? What material do you use? Have you had any problems with it de-laminating in the future?

    FYI, during our "print full sheet and cut printed acrylic" scenario we never had an issue with registration or weird cuts. Our only issue was scrapes to the back of the acrylic and edges where we were concerned the ink would start peeling off.
     

    Attached Files:

  5. WYLDGFI

    WYLDGFI Merchant Member

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    Im going to disagree with some of you guys on the router then print portion. We do a lot of this. Print 2nd surface on the acrylic first then router. Caldera has the Mirror all option now and you can print everything 2nd sided. Our inks and router do a great job on the DA acrylics. If you are using standard acrylic, there could be adhesion issues if chipping or other issues are occurring. We never go to MDF...always us a spoil blanket on our Colex machine. Make sure you have PLENTY of bits on hand.
     
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  6. marunr

    marunr New Member

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    We do it both ways. For an order of 200 or so I'd probably cut them first. Setting up the registration can be problematic if printing on a full sheet and then cutting because of the orientation of the "0" point. If the router and printer are the same, no problem. Chipping of the ink can occur if it's a bleed, depending on the ink set. For the ink I use, it does occur.
    We are mostly a plastic fabrication shop so we cut acrylic all day every day on several routers. For a nicely finished edge I will offset the first pass .013 and then do a finish pass at actual size. We use upcut bits with 2 flutes for acrylic. Usually this will suffice, though sometimes we will polish after depending on the product.
     
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  7. WYLDGFI

    WYLDGFI Merchant Member

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    He's looking at a hybrid printer there. The most efficient way is full sheets vs precut. A true flatbed, doing individual pre-cut is advantageous with the ability to pin your registration for each pre-cut pc. the FB5XX series is slow on the white ink/cmyk output.
     
  8. bannertime

    bannertime "You guys do banners, right?"

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    I'm sorry, take no offense to this, but how do you bid or win a job and you haven't even figured out how to start the job yet?
     
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  9. Grizzly

    Grizzly Member

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    Good luck with your job!

    1) Do you cut blanks and then print to them versus nesting on 51x100 sheet?
    For this many we would nest on a full sheet and route after. Should have plenty of room for registration marks.

    2) What diameter bit do you use to cut the acrylic? Do you return for a 2nd pass to finish or just one pass?
    We would generally use a 6mm bit for that type of quantity. 2nd pass isn't entirely necessary but we do it and it's a lot cleaner. Acrylic tends to have a lot of static and if the vacuum doesn't suck it up I feel like you can never get rid of it.

    3) Do you used a diamond bit to polish the edges of the acrylic or use another method?

    We use a diamond polishing bit. If you're printing first, and especially full bleed, which we would do, you almost have to use a diamond/polishing bit. Otherwise you can't flame polish because it will burn your ink and singe your white back. You also have to remove the masking on both sides and then you figure out how to handle that clear piece of plastic until it's up on the wall of your customer. It's also a lot of product handling and chance to scratch. Hopefully you charge for it because it does take longer and those diamond bits are expensive. Also, we just upgraded to an Automatic Router Bit Changer and it makes this step sooooo much easier. Take that into account if you have to do it manually, route , switch bits then polish, then a put another sheet on and switch back to route, then to polish etc.

    4) Do you use a backer? What type? When during the process do you apply it? We used to skip the white ink and use white a vinyl backer prior to CNC'ing, but we had complaints from customers about vinly lifting on edges and pulling the ink right off with it. Do you have a better process with vinyl?

    If your going to do it this way, you have to make sure you're using digital acrylic (If your printing full bleed, I would use digital acrylic regardless) or that your ink sticks really well. And this is almost a definitely route first print later because then you're dealing with ink adhesion issues, and then routing through the vinyl and that can create other issues. (Downcut bit to make sure that you don't cause it to lift)


    5) How do you store the pieces after they have been printed/cut before packing/wrapping them, since they are so fragile?

    We would pre cut a cardboard sheet that matches the print sheet first. (Copy the route file that is sent over and cut it out of cardboard) Then as they come off, every piece gets the exact size cover. Then stretch wrap that cover on so you can keep them safe.


    6) For any newbies reading this, our first tests routing 2nd surface printed acrylic did not go so well, because we had placed the acrylic directly on the MDF spoil board of the CNC which seems to have caused a lot of scrapes and damage to the image/ink. Now we are using mats from X-edge (MatriX Mat) and that seems to have solved our "ink scrape issues".

    Acrylic should have masking on both sides, only pull the one side of for printing and then route with the print side up. That way the side that is down on the router is better protected with the masking.
     
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  10. sbergman

    sbergman Premium Subscriber

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    Sep 13, 2012
    Paterson, NJ
    First off, thanks everyone for your time and advice.



    Is it your standard to include a backer or only by request or never? If so, what material do you use and when in the process do you apply it? Assuming I nest on a full sheet then route on the CNC I suspect you are suggesting the backer would go on right before packing? A little annoying, because we have holes for the stand-offs, so those would just need to be cut by hand. Any tips?

    I understand that you are suggesting to route the acrylic with the white ink/printed side facing the router and the masked side of the acrylic against the spoil mat. For our product we need to have the acrylic flipped the other way (white ink against the spoil mat and the masked side facing the router) so we can use the router to break the edge of the acrylic. We and our customers find that the edges are pretty sharp, so our first step on the CNC is to break the edges.

    Thanks again.
     
  11. Grizzly

    Grizzly Member

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    We don't use the backer, we just use white ink. If we were going to do it though, I would apply it to the whole sheet and then route. I agree that it's annoying trying to apply it after and then trim out the edges and holes.

    I agree that acrylic is sharp when routed. So do you only break the edges on one side? What does breaking the edges mean? Do you use a radius bit for that? Curious because I've had this same thought of sharp edges and how to address that.
     
  12. ColorCrest

    ColorCrest Active Member

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    Possessing the quality of "charm" is one way, at least.
     
  13. sbergman

    sbergman Premium Subscriber

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    Sep 13, 2012
    Paterson, NJ
    To create the broken edges we use "Amana's DRB-418 CNC Polycrystalline Diamond (PCD) 90 Degree Engraving, V-Grooving and Chamfering Router Bit 1/2 Dia x 3/8 x 1/4 Shank". We only break the edge on the viewer's side, because it would be too complicated to flip the acrylic when the fiducials/registration marks are gone.

    We radius the corners with the tool that is performing the main cuts.
     
  14. Grizzly

    Grizzly Member

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    That's cool. How much do you actually bevel it?
     
  15. sbergman

    sbergman Premium Subscriber

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    Sep 13, 2012
    Paterson, NJ
    1/64" deep from surface and 1/32" off-set from finished edge. Just enough to take off the edge but not so much to change the appearance from afar. Close-up you can tell, but from a distance you don't notice it.
     
  16. Bly

    Bly Very Active Member

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    Do you polish the beveled surface?
    We do them like Griz.
    The Zund has an auto bit changer so route with 6mm bit then diamond polishing is easy.
     
  17. sbergman

    sbergman Premium Subscriber

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    Sep 13, 2012
    Paterson, NJ
    The DRB-418 is a diamond tool so it polishes as part of the edge breaking process; therefore, no additional steps are needed.

    We have a Multicam 3000 with automatic tool changer, camera, drag knife and oscillating knife. It was purchased primarily for woodworking with graphics finishing as an afterthought.
     
  18. Bly

    Bly Very Active Member

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    Nice. You should have no trouble then.
     
  19. ikarasu

    ikarasu Very Active Member

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    Do you guys have a flatbed application? We'd print on clear, laminate it with white...then apply it to the acyrlic. I've never liked how our FB500 printed on acyrlic... It's also pretty slow, especially when printing white. If you print on a full sheet, you will likely have some ink chipping... And if you print 1 by 1, there isnt really a way to not print on the belt -

    You cant tape all 4 sides because you wont be able to push it against the alignment bar. you'll be struggling each piece trying to get the tape to go underneath. Best option if you go that route would be to female cut the shape out of alupanel or some other material as close as you can without too much struggling and use it as a jig...then itll print on the jig and not on your bet, or at least hairline on your belt.

    I'm wondering if all the overspray will get on the egdes of your acrylic though - if you pre-polish it may ruin the job with overspray by printing that much bleed. It may not... we generally print on thin material so it could be ok.

    I'm thinking if you have a application table, itd be faster to apply 200 pieces of vinyl than it is to print photos on acyrlic, then have a second pass printing white... The FB 550 is so slow. And it'd be more durable / look better
     
  20. Jun Lanon

    Jun Lanon Member

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    I do a lot of these. I usually pre cut and line up the sheets on a flatbed with extra space in between for edge bleeding and print multi copy. One hit one click print including white and I move to the next load. For glossy edges, I just do a little touch of torch to make it smooth and glossy before printing.
     
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