Pre-press, press, post-press applications
Vacuum is required for a variety of applications in the pre-press area, including preparing images and film for scanning or exposure and for copying printing plates. There are also many applications where over-pressure is needed as well, such as for guiding plates or film in automatic systems. In classic sheet fed offset presses, vacuum and overpressure is always needed for paper handling - at the feeder to separate the sheets, to feed the single sheets to the different colour-aggregates or to guide the sheets through the machine.
All these applications need different amounts of air at different pressures. There are a variety of applications in the post-press arena. For example, side channel blowers for folding and cutting machines; pressure-vacuum pumps and individual vacuum pumps and compressors for collating and book binding machines; and radial blowers for removing waste paper.
Vacuum is used throughout the forming section of a paper machine to remove water from the paper stock. In the forming section, varying levels of vacuum are applied across the flat boxes and couch rolls to remove the bulk of the water.