New to Dry offset UV curved surface printing

Hi All

I have recently registered onto this forum so hello to everyone. I have a long backgroung in litho & DI operating QMDI Komori 40" & heidelberg XL105 and various smaller machines over the years also quite extensive experience in letterpress embelishing & bindery. I have recently taken on a role as print manager in a plant pot manufacturing company where we are running polytype BDM series presses. my question is if there is anyone else using these presses to print on a tapered container & having trouble with the print length on the head & foot of the container due to the difference in circumference, the problem causes the type to slur and only print sharp in the middle of the container. If anyone has any ideas it would be much appreciated.

kind regards
Darren

 

why not solve it in Prepress ?

same is done with printing IML for the paint bucket (plastic) industry
simply calculate and go in revers so that when you print you get a good sharp image

 

Hello Darren,

I am very familiar with the dry offset process, and what you are describing is a headache that has always been there when trying to print on a tapered container. Because the container is tapered, the surface speeds are different from top to bottom, and it creates different amounts of friction top, middle and bottom of the container when the blanket is rolling across the cup applying the ink. Slur is sometimes the word used to describe this....and in the middle of the cup (pot) is called the "sweet spot" where there is a minimum amount of slippage. A halftone screen will print nice and crisp in the middle of the taper, but when you go towards the bottom of the pot, all of the dots will have tails on them (slur) creating a lot of dot gain....on top of that, the dots at the bottom of the container will actually print closer together, as if it were a higher line screen....which equals tons of dot gain. VanDam has come out with a dry offset conical printer that prints to the container with tapered rollers and cylinders to eliminate this phenomenon.

Long story short, the distortion in print that you are referring to is inherent in the process of printing on a tapered surface...and most try to compensate for this by reducing ink flow towards the top and bottom of the print.

Hope this helps. I'd be happy to discuss this with you in more detail if you wish. We are at dryoffset.com.

Have a great day,
Ron

 

Ron = I am new to this forum (today). I have been screen printing for a few years as part of a printing technology group. A request came across about how we would print graduations and a logo on the outside of a plastic tube/plastic lab tube. One of our folks said we could print 400/min using a prototype bdm off-set press. I didn't think that technology would be an option because the the tubes are 2-3mm thick, the graduation printing needs to be raised and very crisp. I thought a screen print technology would be more appropriate (moving screen, rotating tube, 2 dozen spindles on a rotating wheel) for the print quality needed. Any thoughts?

Greenprint