- May 01, 1996, Boyle, Edward
Though gravure wasn't for you? Think again. With innovations in equipment and technique, costs are coming down, and the process is becoming accessible to more and more converters.
Rotogravure printing has traditionally been known for two things: high quality and similarly high operating costs. Multimillion dollar presses and expensive engraved print cylinders have kept many converters out of the gravure market. Recently, however, suppliers of capital equipment and ancillary materials and supplies have been developing innovations and "short cuts" that have made the process less costly and more efficient. From combination presses to lightweight coating sleeves, these products are making it easier for converters to produce gravure-quality packaging more efficiently and less expensively.
Gravure remains, in our minds, the premier printing process in a variety of applications and appears to be gaining acceptance as the cost of competitive processes increases," says Robert Rodemich, president of International Machinery Inc., Alpharetta, GA.
A Winning Combination
The rise of combination presses, with interchangeable print stations that can combine flexography, offset, letterpress, screen, and gravure technologies, now allows many converters to deliver gravure quality without typical gravure prices. Unheard of just a few years ago, combination presses are now available from virtually every major press manufacturer, though, reportedly, few offer gravure print stations.
W.R. Chesnut Engineering, Fairfield, NJ, last year introduced the Model 180 combination press that features convertible flexo and gravure print stations. The press features sleeve-type technology for both the printing and impression cylinders. It is also available with other efficiency options, including high-performance drying for water-based inks and ultraviolet dryers, as well as in-line finishing options such as rotary die-cutting, sheeting, perforating, and embossing.
In addition, the company has introduced the "polymetric Rotogravure Image Carrier," a plastic-coated, ready-to-engrave rotogravure cylinder that is said to maintain the quality of conventional engraving at a cost and turnaround comparable to flexo. Both are designed to broaden the user base for gravure by making the technology less expensive and thereby more accessible to converters.
Some short cuts are actually flexo-related. For example, Adolph Gottscho Inc. has developed the high-speed "Gotavure" continuous-motion flexographic imprinter that eliminates the purchase and storage of preprinted web stocks. The unit can imprint crisp, clear, large and small graphics, reportedly with gravur-type print quality, on all types of paper, film, and foil. The printer can also produce scannable bar codes at speeds up to 500 fpm on a continuous motion web.
Results are accomplished by an advanced flexographic doctor blade system and anilox roll combined with the appropriate solvent- or water-based ink. Available in widths of 6 in., 12 in., and 18 in., variable-circumference print-wheels from 11 to 24 in. are easily changed for different repeats.
Quick Changeover Aids Process
While developments on the press side have increased the use of gravure technology, most of the innovations involving this well-established technology have come off-line. For example, Kroenert Corp. offers a variety of time- and money-saving systems, some of which are available elsewhere on the market. Kroenert has developed a lightweight, quick-change backing roll sleeve that is easily handled and can be changed in just minutes. The sleeves are composed of fiberglass with a rubber cover, making them extremely lightweight. Consequently, they can be manufactured in diameters of up to 12 in. and lengths of 5 feet or longer yet still be easily handled by a single pressman.
Used primarily in gravure coating applications, the thin-walled sleeves are easily mounted on a mandrel, which can be cantilevered for use. High-pressure air injected on the drive end of the unit easily ejects the sleeve from the mandrel, resulting in a changeover time of just three minutes.
"Instead of dealing with traditional heavy backing rolls with a steel shell," explains company VP George Walthy, "they're now handling and storing these very light sleeves, which cost about two-thirds less than a steel roll. It's a very efficient economical system."
Another shortcut developed by Kroenert that has improved efficiency is a modular trolley system designed for quick changeover of coating systems. The trolley system allows every component needed for a job, from coatings to rolls and doctor blades, to be assembled off-line for fast job setup.
"In just ten minutes you can change your coating and gravure cell size," notes Walthy. "It's a tremendous time-saver and ideal for operations that change product four or five times a shift."
Kroenert has also developed a "chambered" doctor blade system for use with gravure technology. The double-doctor blade system is totally enclosed, virtually eliminating solvent evaporation and contamination and prolonging roll cell life. The system has also been found to control foaming in water-based coating operations.
"Using this system, customers have been able to run certain coatings that they weren't able to run before" says Walthy. "It's very exciting."
Doctor Blade Offers a New Angle
Angle Blade Co. has developed a doctor blade design for gravure applications that offers spring load tension and high angle contact. This allows the printer and converter to wipe the cylinder cleanly with a light spring load and preserve the cylinder while improving quality. This specially designed blade reportedly works better than traditional blades that are "doctored" because of the unusual angle of application.
"The cleanest wipe is achieved when the contact angle is about 80 degrees" says company president John A. Weeks. Doctoring a cylinder with a conventional flat blade does present problems. The press geometry may not be capable of doctoring large cylinders at that high angle, particularly when the doctoring must take place close to the nip."
With a conventional blade, adds Weeks, the major obstacle of the high contact angle is total indicated runout [T.I.R] that may result from an out-of-round cylinder or a worn bearing. Since the conventional slat blade has little or no resiliency at high contact angles, machine operators resolve the problem by flattening the blade. This results in streaking and hazing, plus loss of control over coating weight These problems are eliminated, and efficiency improved, with the angle blade, according to Weeks. "The straightest line to efficiency is scrap reduction," he says. "That's what this blade does." (See Paper, Film & Foil CONVERTER Oct. '95, p. 66, for more information on Angle Blade.)
One of the best "short cuts" to entering the gravure market, says Robert Rodemich, is to purchase used equipment. "With the current trend toward lower prep costs and better process management, most of which can be retrofitted to existing used gravure presses, we envision the prospect of a growing interest in the gravure process."
Interest is growing, in fact through every one of the innovations discussed here, all of which have served to encourage an increasing number of converters to utilize gravure technology to improve end quality.
International Machinery Inc. Alpharetta, GA; ph: 404/442-9264; fax: 404/664-0452. Circle 171.
W.R. Chesnut Engineering, Fairfield, NJ; ph:201/227-6995; fax: 201/227-7873. Circle 172.
Adolph Gottscho Inc. Union, NJ; ph: 908/688-2400; fax:908/687-9250. Circle 173.
Kroenert Corp., Cedar Rapids, IA; ph: 319/366-6200; fax:319/366-5230. Circle 174.
Angle Blade Co., Plattsburgh, NY; ph/fax: 518/563-2049. Circle 175.