Shorter runs drive advances15 June 2004
Drupa proved fertile ground for converters interested in gravure, reports Pauline Covell
"There is a renaissance of gravure in packaging print," said European Rotogravure Association secretary general James Siever. He revealed that gravure's packaging market share worldwide was 22 per cent and was increasing at a greater rate than flexo, which is currently on 30 per cent. Offset was the loser (declining from 40 per cent).
"In flexible packaging, flexo holds 55 per cent with gravure taking 30 per cent," he added. Interestingly shares vary across the globe. In North America, for example, where flexo is king, gravure holds 10 per cent to flexo's 75 per cent whereas in Japan, where gravure has the crown, flexo holds only 5 per cent of the market compared with 85 per cent for gravure. Gravure also has a stronghold in decorative papers for wall and floor coverings.
Trends at drupa on the press front continued to offer reduction in makeready and change-over time. But it was the big shift to shorter run gravure that was driving the technology. The ES970 press from Cerutti shown running on the company's stand was a perfect example. According to Carlo Ardizzone: "It is designed for short runs. It's not a first machine – more for converters needing a press for repeat runs and higher productivity." Typically, it is said to be ideal for print for multinational brands where the same design is repeated many times to avoid large stock holding. The first press had been sold to Amcor, Australia. Designed for runs of between 5,000 and 50,000m, the press offers a production speed of 300m/min.
As well as a shaftless version, the 970 is offered for impression cylinders with shafts where increased automation reduces production costs. A special trolley allows automatic removal and replacement of the print cylinder and inking unit or only the print cylinder or inking unit. Once positioned, the trolley is locked to the press. For integral cylinders guide levers on the side allow for removal and insertion: for the shaftless cylinder two levers on the trolley allow for the same operation.
The print unit is designed to use the ink drums directly, so there is no need to clean the special reservoirs. A washing circuit is automatically connected to the ink and solvent lines. Pump, connection circuits, print cylinder, doctor blade and inking pan are all cleaned and dirty solvent discharged into the special reservoir without contaminating unused inks. So when the trolley is removed from the press, the cylinder and pan are already clean.
Short run gravure was also the target for flexibles press specialist Uteco. The new gravure press launched at the show is designated the Q-Press. The company has developed an on-press quick change of the engraved sleeve, and an on-press quick change of the pressure sleeve, without tools. There is shaftless direct drive to the engraved sleeve, automatic on-press washdown, and doctor blade position is held in memory for repeat work.
The Q-Press prints in widths of 800mm to 1,200mm, with a repeat range of 450mm to 920mm, all at a speed of 300m/min. Operator controls are through touchscreen high colour graphic interface.
The new generation RS 4004 press from Bobst Rotomec, of which a unit was shown during drupa, is said to slash make-ready time by 50 per cent. In addition, substantial reductions are possible in waste materials - web substrate, inks and solvents - and savings in time and labour costs for washing operations are also made, claims the company. With no removal of parts, the simplified machine design is more user friendly, more accessible and more reliable, it adds. Consequently, "The new press delivers more production time, much improved machine productivity, a more rapid return on investment and increased profitability for converters."
The completely new design is said to make the press "the ultimate solution" in short run gravure printing for flexible packaging materials. Trolley change-over is fully automatic, activated simultaneously on all printing units, and the dedicated washing system is specifically designed to minimize makeready time.
A new series of its Rotospeed ID press, the 3001/900, was displayed by CMR. Main features of the ID series are electronic shafts on every model, removable trolleys and a stainless steel drying hood. With a new anti splash protection, it is said to be capable of a running speed of up to 400m/min.
The ID concept can be used for a maximum web width of 1,650mm, but the mid widths like 600, 800 and 1,000mm have a new print cylinder extraction system. Using the steel cylinder in sleeve format allows for quick change, says CMR. The company has also developed a new washing system aimed at reducing press downtime. The water based washing solution is recirculated. Print cylinder and inking system are cleaned in one operation, it explains.
Although Windmöller & Hölscher has placed its main focus on flexo, it considers there is still an important market for gravure. "We have sold presses in the past and will in the future," said Alexander Lohmann. In the Heliostar G he claims the company has "a rotogravure press that is state of the art". The first installation is a Heliostar GE line supplied to a medium sized packaging printer. It features 10 print stations, but it is understood that a further two units will follow. The modular design allows for customized press configurations to meet specific user requirements and market needs, says W&H. "Additional features can be easily retrofitted to extend applications." The first user has a gearless GE with Ecoplus automatic makeready system designed for easy and fast job change-over and minimized downtime.
Other major developments in the field of gravure spotted at drupa feature cylinders and engraving. Creo's partnership with Milan based Acigraf, which has resulted in the Exactus thermal gravure system, combines two mature technologies to provide cost savings, superior imaging quality, improved process control, and enhanced throughput, it is claimed. Significantly, it makes Creo the first prepress company to offer technologies for the three printing processes that dominate the market today — offset, flexo and gravure.
The Exactus system combines Creo SQUAREspot thermal laser imaging heads and the electrolytic copper removal process developed by Acigraf. While the system uses the same copper cylinders that gravure printers have used for decades, the key difference in the Creo-Acigraf process is that the cylinders are imaged by Creo's thermal laser imaging technology. It is expected to reduce the cost of the gravure cylinder process significantly .
"The process comprises five steps," Exactus product manager Moshik Ben-Shlomo explained to Converting Today. "The copper cylinder is first coated with the Graviti thermal resist layer. It is then imaged using SQUAREspot. The character of the resist is then changed in the developing process, breaking the polymer where the laser has hit." Then, in the reverse to the coppering process, the cylinder is put in a tank where the cylinder is the anode and a mesh around is the cathode. "The copper is removed from the unprotected areas. Finally a water based solution is used to remove the remaining thermal resistant layer."
Specially developed by Creo, Graviti is non ablative so a complex debris removal system is not required. There is no redeposit of coating particles. The 3,200dpi SQUAREspot laser head with 208 beam single-head design used is said to ensure superior image quality and improved process control. Four cylinders can be processed per hour, reducing significantly the time it takes to image each cylinder, but Moshik Ben-Shlomo says that the next stage is to double that. "It is an aggressive goal, but we are committed." The system has been on alpha test at ICR, Milan, for over a year. "As we speak," he revealed during drupa, "the first full line is going into a plant in the USA."
Hell Gravure Systems used drupa for the world premiere of the prototype of a laser engraver which creates the gravure cells directly in a copper or chromium surface. Heart of the process is the newly developed laser, which provides the power density required to process a copper or chromium surface. Laser controls enable cell depth profiles to be freely selected, to a large extent.
This method can be used to set the write resolution of the laser independently of the gravure screen and achieves a level of contour definition otherwise only attained in offset, claimed Hell. For example, text can be reproduced with a resolution of 1,000 lines/cm and images in a 60 lines/cm screen. In 2005, Hell plans to launch a laser engraver for packaging gravure. "The price/performance ratio (comparable to that of electromechanical engraving), the improved text repro- duction and enhanced quality in semi autotypical image reproduction will give a welcome long term boost to the gravure sector," it said.
A new generation of gravure cylinder surface treatment from Daetwyler was displayed. The Duostar is a multi functional machine capable of cutting, grinding and polishing, as well as machining the radius and the cylinder sidewall, in one process step.
Equipped with the latest liner drive technology for the carriage, the equipment reaches speeds up to 36m/min, says the company. Automatic measuring of the grinding stone height, as well as an automatic stone dressing device are features and the Duostar can be controlled by the terminal touch screen or remotely through the host computer of a production line.
"Gravure could grow further," concluded James Siever. "Gravure printed packaging is the first choice for brand name goods because of its excellent image reproduction, brilliant colours and consistency over the whole run."
|Bobst Rotomec Tel:+39 0142 4071 Cerutti Tel: +39 0142 459411 CMR Tel: +39 02 99045363 Creo Tel: +1 604 451 2720 Daetwyler Tel: +41 62 91937 37 ERA Tel: +49 89 439 5051 Hell Gravure Systems Tel: +49 (431) 2377 0 Uteco Tel: +39 45 6174555 W&H Tel: +49 (0)5481 140|