Offset CI8: quality with efficiency
The latest technology advancements in Comexi CI8
Offset printing has clear cost and efficiency advantages regarding consumables, job preparation and set-up, when compared to traditional printing technologies. And due to the large choice of different screen types and high line-counts, in combination with Comexi CI8 unmatched central impression cylinder technology, this printing solution also offers clear quality advantages.
During the past few years this innovative printing technology has evolved a lot, not only on press side, but also ink and film manufacturers have developed significant advancements in order to widen the range of offset applications in flexible packaging. Currently, Comexi offset technology is a worldwide recognized technology. In the past months, Comexi and its partners have introduced new developments in consumables and have launched novelties in press features in order to further boost this solution.
Widen the range
Offset ink formulations for printing on flexible packaging films are polymer based. This requires an electron beam unit on the press to transform the inks from a liquid to a solid state.
From early on, the absence of solvents in the inks is an important and positive driver for offset but due to their polymeric character, the first generations electron beam curable inks needed some modifications in formulation, in order to achieve a good performance level on a wider range of flexible packaging films. For this reason, Comexi’s Offset Business Unit is partnering with leading EBC-ink manufacturers. Newly developed EBC-ink formulations bring a significantly better performance.
Moreover, flexible packaging film manufacturers have also been actively contributing in growing the range of packaging films with optimized characteristics for EBC-inks in order to widen the total range of applications.
The previous optimization actions are not surprising, as one has to consider that the flexible packaging market has been dominated by solvent based printing technologies for decades, and Electron Beam Curing offset is relatively new to this market segment.
Press and periphery efficiency
Comexi’s recent improvements on press side are mainly focussed on efficiency. Easy and fast job preparation, and accurate job set-up, contribute largely to timesavings and cause a minimum of waste meters. One key aspect in this is the so-called CIP3 protocol, which has been developed in the decade of 1980’s by a consortium of printing and pre-press companies. Based on area coverage information, derived from the CTP data, CIP3 calculates ink-key pre-settings. The closer each ink key is pre-set to its optimal position, the faster and with less waste meters the print job can be started.
Recently, Comexi’s Offset team has improved the conversion of the CIP3 data to achieve even better first time right colour matching and faster job start-up.
In Offset Innovation Day Open House, the group introduced a new feature that is a great help for printers to control colour consistency during a print job: the Closed Loop Colour Control system (CLCC). This system is capable of measuring small colour deficiencies during a print job and automatically remotely adjusts the individual ink keys in order to accomplish the required correction of the colour.
Although for the moment the CLCC system requires printed reading marks, in the form of a bar of small square patches over the width of the web, Comexi’s efforts in research are focussed on future systems that will be able to work without bar, gathering the required colour information directly from the printed design.
The CI8 press has many outstanding ergonomic features like for example, print sleeve exchange by robot, automatic washing of the print decks and auto-web threading function, but the Offset R&D team saw room to broaden and increase the whole ergonomics and performance of the machines.
One aspect that has been improved is the Cylinder Service Station, that is used to mount and demount offset plates and printing blankets on to the sleeves, and that is typically is located in the pre-press area. As the pre-press area is not always near the press, and logistics for single sleeve inspection or when needed plate or blanket replacement, can be time consuming. In this sense, Comexi has developed an adaptation that allows direct integration of the CSS with the offset CI8 press by means of the robot.
Another recently development that contributes to web savings is the web-retreat function. This function, developed by Comexi’s Offset team, ensures that every time the press is stopped, the so-called run-out meters are pulled backwards from the rewinder, passing through the press, and collected on the unwinder. In this way more than 40 meters of substrate is saved at every stop/start of the press.
Up and down stream print stations for additional in-line gravure and flexo printing, developed by Comexi, are already implemented on several Comexi Offset CI8 customer projects. Adding these printing technologies to the machine allows an increase of its range of applications, introducing in-line solvent based and water based varnishes and whites and cold seal applications.
And what about the future?
Today and also in the future Comexi’s Offset Business Unit and its industry partners will continue to work on innovating its revolutionary offset technology in order to offer our customers advantages in efficiency and quality, and in that way, growing its position in the market place.
By Adelbert Schoonman
Manager R&D Comexi Offset Technology