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Gravure going for short runs

'Pit-stop' change-over and ES designs push speeds

Rotogravure still sets standards of quality. Despite the enormous strides made in the flexo process, it manages to retain its hold for producing some of the best graphics and product performance characteristics available today.

Higher press speeds and low waste are amongst the benefits of rotogravure. The process is simple to execute and is favoured especially in some regions where highly skilled operatives are in short supply, for example China and parts of South America.

Said to be capable of slashing make-ready times by 50 per cent, the first of a new generation of Rotomec 4000-4 ES rotogravure presses announced during CMM has been commissioned in the Valmet Converting Technology Centre (CTC) at Valmet Rotomec, near Milan.

Developed in response to the continuing trend towards short run gravure printing for flexible packaging materials, the press will be the main focus of attention at an Open House at Valmet Rotomec in Italy, during GEC, Milan, from June 6-10 .

Radically different in looks, it is claimed to be the first gravure press specifically designed to minimize makeready time of a trolley type press.

Peter Medlicott, executive vice president of Valmet Converting, Inc, told Converting Today during CMM: “Gravure is now perceived as a short run process. In 1996, we took a major step forward in gravure with the electronic line shaft. We sold 30-35 gravure presses over the last year and all but one were electronic line shaft models. And high efficiency dryers now allow high line speeds.

Makeready slashed

“The next step was to emulate Formula One racing for change-over speeds. With the new press we have achieved this. The 50 per cent reduction in makeready time results from a ‘pitstop type’ fast changeover.”

Completed in only two minutes, the trolley change-over is fully automatic and activated simultaneously on all printing units. Washing of the printing cylinders and cartridges is performed off-line, close to the press and is much simplified by the fact that the stainless steel trolleys can be completely enclosed inside the washing machine for cleaning. The washing machine is specifically designed for the simultaneous washing of inking parts and the printing cylinder: no parts have to be removed from the trolley.

“What is saved by the 22min job change-over on nine units with five job changes a day equates to almost a full month of extra production over the year,” added Peter Medlicott. “Setup is achieved in less than 150m of web material, thus saving ink and energy as well as material. Instead of three operators needed for a nine colour change, one plus a helper is enough.” Ink circulation around the cylinder drum is reduced to 6-7 litre, providing more energy and cost savings, says the company.

Each press will be custom built in 800-1,400mm web widths and 400-920mm cylinder circumferences. An operating speed of 350m/min is claimed. Solvent or water based inks can be used and in-line coldseal and lamination will be possible.

Perhaps the most important issue to converters is continually to improve the annual square metre production of usable product. The 4000-4 ES can “significantly improve this” as a direct result of the electronic shaft (ES) system. Dramatic reductions in wastage of material is achievable through the rapid control of registration during both the acceleration and deceleration phases of the printing cycle, claims the company. “In certain cases this can amount to material wastage reduction of up to 40 per cent.” Much lower web wastage also reduces consumption of inks and solvent, and leads to substantial increases in profitability for the converter, the company adds.

A new 10 colour Biva 4 gravure press has been installed by DCM at a German converter. Printing width is 800mm, but is still said to preserve all the advantages of the company’s narrow web concept. The engraved cylinder shaft remains cantilevered while the gravure sleeve is transferred from a trolley in and out of the machine. The sleeve type impression roller can also be slid out in the same way without removing the sleeve mandrel.

Amcor Flexibles Envi (part of Amcor Flexibles Europe) held the official inauguration of a new extension to its production facilities in Assen, Holland earlier this year, which included the installation of a Rotomec 3000-3R ES, 10 colour press.

Committed user

Envi, a long established customer of Valmet Converting, already has three Rotomec gravure presses, plus a Titan SR6 and two Atlas slitter rewinders. The new press features the ES technology together with a facility to coldseal coat and with in-line dry bond lamination. It handles web widths up to 1,100mm at speeds of up to 300m/min.

Uteco Converting claims to have made serious and largely successful attempts to address the areas in which gravure suffered from a perceived weakness, with the result that the cost difference between the processes of flexo and gravure is not as great. The development of lightweight interchangeable trolleys on the company’s range of gravure presses, together with print unit washdown facilities and/or on-press impression roller sleeve change provides for speedy job change-overs and make-ready. In addition, for added value work, in-line operations such as coldseal, PVdC, varnishing, laminating and sheeting can all be undertaken on Uteco’s Programm gravure presses. UK agent Eurograv’s Alan Attard also notes that developments in laser technology for the engraving of cylinders have speeded up cell production, shortening downtime still further.

Uteco’s range comprises six base units, which can be manufactured in widths from 500-1,900mm and for speeds of 650m/min. They incorporate electronic line shafting and can be supplied with a wide range of options.

Bobst Group USA has announced the sale of a Schiavi nine colour Idea gravure press with on-press wash-up system, printing cylinder automatic change-over, Bobst Registron automatic register control system and press drive through electronic line shaft (ELS). To be installed at Inland, in La Crosse, Wisconsin it is scheduled for production start-up in December.

The new press will be equipped with a specialized system for drying water based inks at high production speeds. In addition, the Idea provides for “ultra fast job change-over” thanks to on-press washing of the inking system, doctor blade and printing cylinder, as well as the cylinder change operation, which can be set up whilst the machine is still printing.

The press includes an in-line rotary embosser and sheeter, and can be operated either for roll to roll or roll to sheet. A secondary web unwinder is included to allow the press to be run in tandem for roll to roll and roll to sheet operations. In total, nine distinct web path sequences are possible, giving Inland several press usage options.

Bobst Schiavi

Tel: +39 05 234931. www.bobstgroup.com

DCM

Tel: +33 1413 75270. www.dcm.fr

Uteco

Tel: +39 045617 4555. www.uteco.com

Valmet Rotomec

Tel: +39 035 659 1011. www.valmetconverting.com