The 250-plus print pros attending the 2nd Hybrid User Meeting on 21 and 22 April at KBA’s sheetfed facility in Radebeul certainly found plenty to interest them. Alongside new advances in hybrid coating, emission tests on the 18,000sph Rapida 105 and the results of consumables trials, KBA announced a new standard, Printsecure, for statistical process control.
KBA assumed a banner role in hybrid technology after demonstrating this revolutionary yet cost-effective coating option, which is based on the application of two different types of ink (hybrid and oil-based), at Drupa 2000. The group has since expanded this role to embrace other technological innovations in sheetfed offset, and as a result has sold more than 200 hybrid presses for sheet formats from B2 to size 7-plus (27” to 64”). The vast majority of these presses are already on stream. Cut-throat pricing for standard printed products has steadily expanded the circle of hybrid converts, and KBA staged a second user meeting (the first was back in September 2003) to bring users up to speed and promote a vigorous exchange of information. Participants from all over western Europe were joined by some from the USA, India, Japan and several other countries.
Seal of quality for consumables
Jürgen Veil, head of sheetfed offset marketing at KBA, outlined the technical criteria that apply in approving consumables and systems components for hybrid production. Most early adopters of hybrid coating were packaging printers, but over the past twelve months commercial printers have accounted for a growing proportion of the 50-plus shipments.
Teething troubles caused by a shortage of suitable consumables have long since been remedied, and today there is a plentiful supply of hybrid inks (incl. special inks), cleaning agents, oil-based varnishes and UV coatings.
However, users have been unsettled by instances of consumables being labelled as hybrid-compatible when they are totally unsuitable and could even cause press damage. To address this issue, last year KBA commissioned FOGRA to conduct a series of tests.
After announcing preliminary findings for some 600 different washing agents, blankets and roller materials, Jürgen Veil and Dr Wolfgang Rauh of FOGRA awarded the first hybrid-accredited certificates of approval and quality seals to the selection of inks that had already passed all the tests: Starbrite (Epple), Gemini Process (Flint Schmidt), Sun Cure Hybrite (Sun Chemical) and Novabryte BF Process (BASF). These, along with the various washing agents and UV coatings still being tested, ensure a stable, reliably reproducible print production. Others will soon follow.
RAPID Dry: new-generation dryer from KBA
Jürgen Veil also unveiled a new dryer that KBA has developed specifically for Rapida sheetfed offset presses. Existing IR drying systems operate with shortwave and fast medium-wave radiation so as to come up to power and deliver a high degree of efficacy as soon as production starts. Although the new carbon lamps operate solely in the medium-wave range, they come up to power just as quickly as shortwave lamps, are more energy-efficient than standard IR radiation for drying water-soluble inks and coatings, and generate less heat on the substrate. This is because the level of heat generated is controlled automatically by adjusting the actual temperature of the delivery pile relative to the specified target temperature. This helps eliminate pile blocking.
The Rapida 105 delivery and delivery extension can accommodate a full 18 dryers (seven IR and eleven thermal) – a lot more than rival models. Also, and this is totally new, the dryers can be repositioned freely to suit the substrate, image and production speed.
On a press running at 18,000 sheets per hour any other type of dryer would soon hit its limits, and even the new carbon dryer features twin-tube emitters to ensure that it can deliver the necessary power level. With the appropriate inks and coatings such a high speed is no longer utopian.
The high level of flexibility is not limited to IR and hot-air dryers but applies equally to UV dryers in hybrid presses. The delivery extension has room for three UV lamps with a maximum power output of 200W/cm per lamp. The lamps can be moved freely between the delivery extension and mid-press dryers by simply unplugging the media plug and inserting it in the pre-installed socket at the desired unit. This ingenious solution can substantially reduce the cost of new presses. On top of this, maintenance is much simpler because the press minder can change the lamps himself as and when necessary.
Eco-accreditation for 18,000sph Rapida 105
Albrecht H. Glöckle, head of prevention at the BG (Germany’s equivalent of the H&SE in the UK and OSHA in the US), described the emission tests that were carried out at the Rapida 105. The press tested at the end of last year was configured with two conventional and two hybrid inking systems applying three UV coatings and one aqueous coating. Three different washing agents were used. All production was alcohol-free (IPA concentration: 0!).
All the readings for the relevant emissions – ink mist, VOCs (alcohol, carbon dioxide), ozone, UV light, spray powder and noise – were below the specified thresholds. At the User Meeting the BG therefore awarded the new B1 press its coveted “emission tested” certificate. Following on from all the other Rapida presses in recent years the new Rapida 105 has thus become the first 18,000sph sheetfed offset press on the market to receive this globally valid environmental accreditation.
According to the BG, process stability when using hybrid inks depends on three criteria: print output, materials compatibility and environmental factors. Output is determined by the press manufacturer and suppliers, materials compatibility by FOGRA and emissions by the BG’s testing and certification unit. But process stability can only be achieved if all three parties work together.
Statistical process control with Printsecure
Peter Stahlberg, a development engineer at Media Service, presented a new software program, Printsecure, which converts colour management readings into data that the press operator can employ directly to achieve the optimum press settings for an immaculate print quality. The results can be depicted in three display modes: basic, advanced and professional. The system is configured for use with a Printsecure measuring strip which is calibrated or printed out in a standardised form, scanned and fed into the system.
In the basic mode a green light signals that all the scan values (densitometric, colorimetric) lie within the self-specified tolerance range. When running a repeat job all that needs to be done is to compare the reference figures for the original job with the current readings – if the light is green, the repeat run can start. A red light indicates that at least one value exceeds the tolerance range. At this point it is worth switching to the advanced mode, where the mouse can be used to move between the various values (eg tonal curves, grey balance, densities). It is possible to zoom in on any part of any curve. The professional mode constitutes a chart displaying the individual values, and functions as the Printsecure system’s “colour memory”. Any value in the chart can be declared a reference value – so it is wise to use only standardised measuring wedges. Deviations from the reference value are colour-tagged for easier evaluation, eg where deviations are indicated but are manifested in a single value.
Printsecure is suitable for all types of printing process and offers the following benefits:
Printsecure can thus be used as a voluntary, self-imposed tool for monitoring quality in the press room.
Representatives of consumables manufacturers were subsequently given the opportunity to present new and improved products.
They were followed by an open forum at which practical advice was proffered on how to deal with various issues raised by participants, eg adhesion of UV coatings on surfaces with a high proportion of solids, the tendency of silicone-based UV coatings to block, hybrid production on GD2 carton, cracking at folds, the impermeability of hybrid inks to light and water, options for applying hybrid inks and UV coatings to film, the consequences for repro etc.
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