Digital Offset Printing Where Are We Now?

A DOP press is a lot like a conventional sheetfed (or web) offset press. It uses plates and blankets, with either the usual 'wet' process inks or waterless inks. So the good news is that you already know a lot about how the press works.

The key differences are the on-board imaging units, the same technology used in many imagesetters and platesetters. Infrared lasers or laser diodes 'draw' the image from the RIP computer directly onto blank processless plates already on the press. On each unit, plates are typically installed in rolls or cassettes of 18 to 36 plates each, and the plates are changed automatically, with the old ones deposited into a used-plate area for removal. The entire plate-change and imaging cycle takes seven to 15 minutes or so on most DOP presses. Then you're ready for the next run. That's a big time savings over the total changeover time required for conventional press workflows, which translates to more jobs per shift, per press and per press person.