Notable digital laser exposure
Digital images are exposed onto true, light sensitive photographic paper with lasers and processed in photographic developers and fixers. These prints are true photographs and have continuous tone in the image detail. The archival quality of the print is as high as the manufacturer’s rating for any given photo paper used. In large format prints, the greatest advantage is that, since no lens is used, there is no vignetting or detail distortion in the corners of the image.
Digital printing technology has grown significantly over the past few years with substantial developments in quality and sheet sizes.
Digital cylinder printing
Digital cylinder printing is when a machine directly lays ink onto a curved surface that usually is the wall of an object that has a circular cross section, and a constant, tapered, or variable diameter. Digital cylinder printing is a method of reproducing black-and-white or full-color images and text onto cylindrical objects, typically promotional products, through use of digital imaging systems.
The digital process is by definition faster than conventional screen printing, because it requires fewer production steps and less set-up time for multiple colors and more complex jobs. This in turn enables reduced run lengths.
The ability of digital cylinder printing machines to print full color in one pass, including primers, varnishes and specialty inks, enables multiple design techniques, which include:
● Mirror prints: viewable on the inside and outside of glass or plastic
● Tone on tone: solid matte-finished substrate enhanced with one ink or clear coat
● Stained glass: color opaque enough to see through
● Contouring
● Etched
Full-wrap cylindrical printing also benefits from seamless borders with no visual overlap. For ease of print file preparation, original design artwork should be able to be imaged on cylinders and tapered items without the need for manipulation or distortion; i.e., flat images will print to scale on a curved surface, with software automatically making the adjustment. The more advanced systems available on the market can handle these requirements.
The digital cylindrical printing process involves inserting a cylinder-shaped item, or part, into a fixture, which securely holds it in place. The part then travels under a print head mechanism in which tiny droplets of CMYK (cyan, magenta, yellow, and black) inks are released in a specific pattern to form an image. Typically, one part is printed at a time and can require from 8 to 45 seconds to complete, depending on artwork complexity and quality. It is then finished with a UV coating to add a glossy finish and protect it from abrasion.
There are three different imaging techniques used by digital cylinder printing machines: multi-pass, single pass, and helical printing.
Multi-Pass: Multi-pass printing is when the print heads or printed object move axially in steps down the part, like a flatbed printer. The move time is inefficient and can lead to stitching artifacts between moves.
Single Pass: Single pass involves using an array of print heads to print the full image length with a single revolution of the printed object. Different colors are usually printed at different stations, leading to higher cost, increased complexity, and sensitivity to print nozzle drop-outs.
Helical Printing: Helical printing is a hybrid method between the single-pass and multi-pass approaches. Image data is mapped to allow continuous imaging in a helical pattern with a limited number of print heads. Users can optimize the print resolution, speed, and curing controls to optimize image quality or choose higher speed if quality isn’t critical. Tapers can be imaged at high speed and curved vessels can be managed through the range of controls offered.
Items that can be printed using digital cylindrical processes include cups, tumblers, thermos bottles, bottles, makeup containers, machine parts, carrier tubes, pens, tubes, jars and others.