Rotogravure, also known as gravure, is a printing system that uses a low-relief cylinder and fast-drying liquid ink, very popular in the publishing and flexible packaging market, it is used in the manufacture of food and non-food packaging, As well as for labels, security, industrial and tobacco printing also have other applications.
In the rotogravure printing process, the images are captured on the paper through a cylinder in which the image is recorded by means of small holes that are filled with ink and later the metal plate is cleaned, leaving only the area of ink to be inked. the recorded image.
All material to be printed is prepared as a positive film on a copper intaglio printing plate to accept photomechanical transfer by means of a intaglio screen. The varying depths of etched cells determine the tones of the printed image, with deeper cells containing more ink (and therefore printing darker) than surface cells, which may not contain ink at all.
In the printing process, the cylinder carrying the printing plates is positioned so that during its rotary movement it passes through a tray filled with a thin solution of fast-drying ink, or is sprayed with ink. A thin steel blade moves through the cylinder and removes ink from the surface of the plate, but not from the small depressions in its cells. The plate cylinder then comes into contact with the paper, and the paper draws ink from the depressions in the plate. In color rotogravure printing, a separate cylinder is prepared for each color.
One of the most important aspects of the rotogravure printing process is getting started. That is, the printing cylinder and its recording so that, later during the production printing process, technical problems are minimized.
Rotogravure is a printing process descended from intaglio.
The first patented rotogravure printing systems date back to 1860 (France). A collaboration between Klic and Fawcett in Lancaster resulted in the founding of the Rembrandt Intaglio Printing Company in 1895, which produced fine art prints. In 1906 they commercialized the first multicolored rotogravure printing.
In 1912, the gentlemen. Bruckman in Munich produced proofs for postage stamps which went into production in 1914. Also in 1912, newspaper supplements printed by rotogravure were sold in London and Berlin (The Illustrated London News and Der Weltspiegel).
In 1932, a survey by George Gallup to determine the relative value of rotogravure as an advertising medium, on the reader’s interest in various sections of Sunday newspapers, found that these special rotogravures were the most widely read sections of the newspaper and that the advertisements were three times more viewed by readers than in any other section.
Rotogravure printing machine is used in flexible packaging manufacturing and printing processes including polyester, nylon, Bopp, aluminum foil, polypropylene, low and high density polyethylene, etc., the most advanced handle double printing facilities face with high speed hot air dryers.
There are also specialized machines for printing polyethylene bag, polypropylene and cellophane and roll paper. It is a kind of printing equipment ideal for producing paper food bags and grocery bags
Publication rotogravure presses operate at 45 feet (14m) per second and above, with paper roll widths greater than 10 feet (3m), allowing an eight-unit press to print approximately seven million pages four colors per hour..
The vast majority of gravure presses print on rolls (also known as webs) of paper or other substrates, rather than sheets.
Rotary gravure presses are the fastest and widest presses in operation, printing from narrow labels to 12 foot wide (3.66 meter wide) vinyl flooring rolls. For maximum efficiency, rotogravure presses operate at high speeds producing wide, large diameter rolls. These are cut down to roll size finishing on a slitter or rewinder.
Advantages and disadvantages of this process
Advantages of rotogravure printing
- Rotogravure is a high-speed, high-volume printing process capable of printing continuous-tone images.
- As a direct printing process, rotogravure results in better ink arrangement and more consistent quality
- Print times are extremely fast, with modern presses capable of producing up to 14m of film per second.
- Rotogravure printing uses fast-drying solvent-based inks to speed up the printing process
- As the process is mostly automated, labor costs are lower
- Rotogravure cylinders are very durable, they can be used for multiple print runs.
Disadvantages of rotogravure printing
- Initial cylinder setup costs can be very high
- Rotogravure printing is not as price competitive as other printing methods, especially for shorter runs.
Products with rotogravure
Rotogravure printing is quite widespread today, and is used mainly in flexible packaging such as snacks and wrappers, as well as editions of books and magazines of great circulation.
Has an outstanding share in the food industry
- Packaging for cold cuts and sausages
- Packaging for sauces and liquids
- Packaging for fish and seafood
- Cheese and yogurt packaging
- Packaging for fruits and vegetables
- Dry food packaging
- Packaging for coffee, infusions and cocoa
- Packaging for sweets, confectionery and breakfasts
- Packaging for nuts, pickles and spices
- Packaging for ready meals
- Packaging for food and dietary supplements
- Packaging for animal feed
Products within the non-food industry
- Chemical packaging
- Packaging for perfumery and hygiene
- Other types of non-food packaging
Cylinder engraving for rotogravure
The beginning of the manufacturing process for a rotogravure cylinder includes the copper cladding of the cylinder or sleeve. Mostly new cylinders are used.
For electromechanical rotogravure a layer of copper is sufficient and for laser engraving an additional layer of zinc is required. The different layers of metal are applied using the required strength and sequence, depending on the special requirements on the rotogravure cylinder. A corresponding mechanical surface treatment completes the preparation based on the etching process.
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Flexographic and rotogravure printing
As stated above, in the high-quality packaging market, rotogravure and flexo printing are the two technologies of choice. Each has its own characteristics and advantages that provide guarantees for all kinds of packaged products. Due to its great development, flexography is a very good option to achieve high print quality.
To choose the most suitable printing technology, one must take into account: price, packaging style, printing quality and the target market.
Rotogravure printing has been accepted as the best technology to achieve high print quality, color printing with excellent graphics, and perfect rendering of lights. For prints over 40,000 linear meters, rotogravure has great price advantages.
Relentless advances in flexo quality in recent years have resulted in it becoming a very important competitor for rotogravure printing.