Printing on Plastic

Print Making
#1

Hi… working on a project idea and I’ve come to the conclusion that screen-printing might be my best option, but I’ll throw the idea out there and see if the collective maker-mind has better options… or can at least point me at the right screen-printing classes to build up my knowledge.

In short, I need to print white lettering on small black plastic cards. The cards will be approximately 2" x 3" with some edge details (i.e. not purely rectangular) and will need to be cut from a larger sheet (12x12 and 12x24 stock seems readily available.) Laser cutting seems logical, so I am presently leaning toward acetal/delrin sheets (1/32" thick) to avoid nasty vapors or other problems from prohibited materials in the lasers.

For my first couple of prototypes, I will use adhesive 2" vinyl lettering; but I will eventually need a fairly large number (20? 50? 100? … maybe more if this project proves successful!) of “identical” sets. (as long as the lettering is clear, small imperfections, slightly off-center, etc. are not a problem.) So… my thought on larger scale production is to screen-print the lettering layouts on the large plastic sheets and then cut out the printed cards on the lasers.

  • Are there suitable inks for printing onto acetal/delrin in this manner?
  • Is screenprinting a reasonable approach? Or are there better ideas out there?
  • Which of the upcoming screenprinting classes might be suitable to get me started?

Thanks in advance!

#2

Have you looked into the two layer materials available for laser cutting? You raster engrave to cut through the first layer and then cut it out. You don’t get a lot of selection if you want 1/32" but it is available.

It’s used a lot for nametags, signs, etc. There are some examples by the Zing laser cutter.

#3

I have, but they are all too thick for my application. 1/32" is just about perfect, and I don’t think any of the two-layer materials are substantially thinner than about 1/8".

#4

Got my edit in as you were replying…

It’s hardly a complete search but here’s one example of a 1/32" two ply material: http://www.bfplasticsinc.com/pc_product_detail.asp?key=37CFDB4138B84274B63CE2D69F7287BF

There’s also this line that gets down to 0.02": http://www.bfplasticsinc.com/engraving-products/gemini-contours.asp

Can’t speak to the vendor as I haven’t used them before.

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#5

Thanks. This could be promising. I’ll look more into it!

Still, I would like to hear from those with printing experience… Learning a new skill is part of the fun! :slight_smile:

#6

Ah… I forgot to mention another complication of the design that will preclude the 2-layer materials: I need images on BOTH sides of the cards! I think I’m back to printing white ink onto black plastic…

#7

haven’t done it, but I don’t think it would be substantially different than screen printing on anything else - this ink says it’s suitable for plastic: https://www.amazon.com/Jacquard-JAC-JSI1119-Screen-Printing-Opaque/dp/B007NONI3W/

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#8

How close does your design come to the edge of the cards?

It may be simplest to cut the cards first. Attach a plate of the same thickness with a hole matching the outline of the cards to your printing machine. You will find registration to be easy.

#9

I expect roughly a 1/4 to 1/2" perimeter that is not printed. My concern with cutting the cards first and then printing is that I need SETS of cards… say, for example, 26 cards lettered A-Z. So by cutting them first, I need to manage 26 stencils/plates/screens as well. If I could instead print the entire sheet (each side individually, of course) and then cut, I can manage with only two screens. (I could of course use a digital printing technique instead of stencils/plates/screens, but the desired aesthetic is white lettering on a black card, which would not be a very cost effective solution, I think.)

#10

You never said how many sets you intend to make at a time.

If your screen is big enough, you can print 8 or 13 cards at a time so that you only need 4 or 6 different screens. Using a plate with multiple holes for the cards makes your work much easier.

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#11

You’re right, of course. But then I’m missing the advantage of cutting first and printing second. The challenge is consistent registration of the material, but I expect that I can register a 12x12 sheet as easily as I could 12 pre-cut cards. Then setting an origin for the laser to one of the corners on the full sheet would be straightforward.

Or did I miss something in your proposal?

And are we still talking about screen-printing? or some other printing process?

#12

I think you are missing the idea of using the “waste” from cutting out one set of cards as a jig to register the cards as you print them. Why would consistent registration be a problem?

#13

No, I understood the idea of the jig. But I don’t understand how that buys me any advantage. Perhaps I need to offer some additional background on the project though to make things more clear.

I am wanting to make a split-flap display composed of a series of modules. Each “module” will be able to display any alphanumeric character (plus space/blank, and 3 punctuation symbols, for a total of 40 potential characters.) by rotating to a specific pair of half-cards. So, for a 10-character display, I will need 10 sets of the 40 alphanumeric half-cards (each half-card will display the top of a character on side A and the bottom of the next character on side B.)

So, with this in mind, I could either print 10 sheets of acetal ensuring that the sheets are registered consistently enough that the characters on the both sides of the half-cards are reasonably aligned, and then cut out each card; or I could cut out 400 half-cards, register a subset of them in a jig and then print them.

The disadvantage of the first scenario is the consistent registration of printing front and back images, but I think that is easily managed and not a real problem, but it allows me to produce entire sets of cards for a single module quite efficiently. The second scenario provide an advantage of maintaining a stock of blank half-cards and I could easily print “spares” of any character (or at least a smaller subset of characters), but it seems more cumbersome when I will be primarily producing complete 40-card sets and very rarely will need smaller subsets of or individual cards/characters.

My prototypes will be one, and then 2 modules, for which I will apply adhesive vinyl letters by hand. Beyond those first two though, I want to be able to produce sets of cards en masse. I can imagine a 140 (or is it 280 now?) character board that displays Tweets, etc.

Does this help clarify things?

#14

these are approx 2"x3", 1/32" thick, already cut, and can be printed by a variety of inkjet printers

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#15

I’ve seen those. The problem is that I am unable to notch the edges with the laser cutters. (PVC is a prohibited material as it emits poisonous chlorine gas when burned or etched.). For this reason, I need to use acetal/delrin or another suitable plastic. Hence my initial request for screen-printing advice.

#16

Technique wise screen printing could work, but we have no idea what inks we would use. We do think any ink that would stick well to delrin isn’t something that we would be comfortable handling due to toxicity concerns.

#17

Yeah, just did a quick Google search and just about any ink that will print on to plastic with any reasonable level of durability is solvent based. The DMS Printmaking area doesn’t allow the use of such inks due to health and environmental issues.

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#18

Thanks @Hardsuit. I think this tells me what I need to know… it’s either outsource the screen-printing (which still might be the most cost-effective solution) or find another printing/lettering technique (possibly coupled with a different cutting/forming technique if I have to change to another material…)

I’ll keep at it… still have plenty of work to do on these first two prototypes.

#19

Use the Shapeoko instead of lasers to cut PVC?

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#20

ok, how about cutting your blanks on the laser from delrin, then applying stickers? you can get inkjet or laser printable vinyl sticker sheets, or outsource the printing.