Goss has revealed white light as its secret weapon in web offset package printing at drupa. The unique technology development is central to the productivity benefits of the Goss Vpak press. The technology reduces set-up and ongoing costs for package printers requiring the flexibility and cost-effectiveness of high-quality web offset.

The white light development is a breakthrough blanket sleeve that reduces the cost and complexity of achieving multiple repeat variations using a Sunday Vpak press. It is the result of collaboration with Flint Group/Day International, longtime supplier of gapless Sunday press blankets.

Goss is certainly not the first to envisage the potential for web offset as a packaging alternative, but solutions have come and gone without making any real inroads due to issues such as costly and cumbersome size-change systems, limited web widths and ineffective supplier support, said Peter Walczak, product development director for the companys variable sleeve Sunday Vpak presses. We have the advantage of 20 years experience and development of gapless blankets, as well as with a track record of executing large-scale integrated installations supported by a solid company infrastructure.

We recognised, of course, that we could not simply take a commercial press, add variable repeat, and call it a packaging press. Instead, we took the proven core principles of Sunday technology and started from the ground up to create a specialised solution.

Size changes are achieved on the Vpak press by sliding cylindrical plate and blanket sleeves adapters of varying diameters over cantilevered mandrels. This is nothing new, although 20 years of gapless blanket sleeve experience enabled Goss engineers to quickly perfect simple size changes.

The innovation of the white light system is the concept of applying a varying layer of lightweight material under the gapless blanket sleeve. The thickness of this white light layer can vary from between 0 to 6mm (0 to 0.25 inches) and reduces the number of blanket bridging sleeve adapters a Vpak press user needs to buy and manage.

For each set of blanket bridging sleeve adapters, a printer can vary the repeat within a range of 40mm (1.57 inches) by using a new set of blankets with a white light layer of an appropriate thickness, said Walczak. This is a far less expensive and complex alternative to buying and organising separate sets of bridging sleeves of both plate and blanket adapters for every single size requirement.

Surface compounds for the blankets developed for the Vpak press are available for UV and electron beam curing and heatset printing.

In parallel with the sleeve change and white light concepts, the Goss team designed the Sunday Vpak press cylinder stack so that ink train rollers and the plate, blanket and impression cylinders maintain a correct contact profile regardless of the diameter of the sleeves. The design work included automatic setting of the plate to blanket nip to ensure ease of operation and fast changeovers.

The result, according to Walczak, is a press design that merges the proven lithography, operability and productivity traits of the worlds most advanced Sunday presses with a size-change capability that is easy, reliable and cost-effective. The system has operated successfully on a wide range of packaging substrates, from films of 12 microns in thickness to heavyweight board.

Goss Sunday presses with gapless sleeve blankets revolutionized commercial web printing and have been setting – and resetting – industry standards for print quality, productivity and reliability for 20 years. More than 2000 Sunday printing units now operate worldwide at speeds of up to 15m per second (3000 feet per minute) and widths of up to 2.86m (112 inches).