روتوگراور چیست ؟ آشنایی با هلیوگراور و جاپ هلیو و بسته بندی

Rotogravure (abbreviated roto or gravure) is a type of intaglio printing process that involves engraving an image on an image carrier. In gravure printing, the image is engraved on a cylinder, such as offset printing and flexography, using rotary printing. The engraving process is used for applications such as advertising prints, magazines, postcards, corrugated cartons and other packaging.

In the nineteenth century, a number of developments in photography led to the creation of printed metal plates for photographs. WH Fox Talbot in 52 refers to the use of integration in the photographic process to create half-shadows in the photographic process. A French invention patented in 60 shows a print of a roll feeding engraver. The collaboration between Klic and Fawcett in Lancaster, England, in 95 led to the founding of the Intaglio Rembrandt Printing Company, which began producing art paintings. In 1906, the first multicolor print was introduced.

In 1912, Messrs. Bruckmann in Munich produced a profile for Bavarian postage stamps, which was finally produced in 1914. Also in 1912, newspaper supplements were published by The Illustrated London News and Der Weltspiegel.

In 1932, George Gallup, in a study entitled "A Study of the Reader's Interest in Various Sections of Sunday Newspapers to Determine the Relative Value of Rotogravure as an Advertising Media," found that pages printed with Rotogravure were widely read and advertised three times as often. Compared to other sections.

Engraving is one of several printing techniques that is actively used in the new field of printing electronic components.

Process and components

In direct rotogravure printing, the ink is applied directly to the engraved cylinder and transferred from the cylinder to the printed surface. A printing unit consists of the following sections:

An engraved roller (gravure cylinder) around which this cylinder can be changed according to the design and need.

Inks (composite pan)

A blade unit (or Dr. Blade)

Pressure rolling (or printing rolling)

Dryer unit

In indirect rotogravure printing processes, the engraved composite roll is transferred to the surface of an intermediate cylinder and then the intermediate rolling is transferred to the printed surface.

Engraved cylinder

The first step in a rotogravure is to create an engraved cylinder of the images to be printed: The engraving process on the cylinder surfaces creates cells that are used to transfer the ink to the printed surface. Because the amount of compound in the cylinder cells corresponds to the intensity of the different colors on the paper, the dimensions of the cells must be carefully determined: deeper or larger cells produce more intense colors, while smaller cells produce the opposite. There are three methods used to engrave gravure cylinders, in which the cell size is uniform or variable.

Cell size method Cell depth

Common (traditional) identical variable

"Two positive" or "Lateral hard dot" variable

Direct transfer of the same variable

Engraving cylinders are usually made of steel and plated with copper, although other materials such as ceramics can be used. Quality trauma cells are created by laser engraving, diamond drilling or acid working methods. In the acid working method, the desired image is transferred to the cylinder in a negative way. Scratch resistance should be considered after acid work. This is similar to making printed circuit boards. After engraving, the cylinder is tested (profile printing), rebuilt if necessary, and then chrome plated to increase the strength of the cells.

processes

While the printing press is running, the engraved cylinder is immersed in the ink, which feeds the cells. Dr. Blade's blade prevents excess ink from reaching non-printed surfaces and transferring it to the printable surface. The angle or position of the blade can be changed according to the application.

In the next step, the printed surface is engraved between the cylinder and the pressure cylinder engages with the same printing cylinder, and this is where the ink is transferred to the roll surface. Pressure is applied from the side of the printing cylinder to ensure that the entire surface of the print is uniformly connected to the engraved cylinder.

When the two surfaces come in contact, part of the ink inside the cells (due to the surface tensile strength of the compound) is transferred to the surface of the roll.

This ink transfer in each unit that leads to the printing of one color must be completely dry before reaching the next unit, so in each unit after the ink transfer and before the next unit the roll will pass through the dryer.

In rotogravure printing, such as flexo and offset, we will have one gravure printing unit for each color, so for CMYK printing, we will have four units for cyan, magenta, yellow and black colors.

But the number of colors in the printing press depends on the number of colors needed to produce the desired image.

Possibilities

In gravure method, the ratio of ink transfer to the printed surface is higher than other printing methods, so the density and viscosity of the ink must be determined.

One drawback to engraving is that all the elements, text, or templates are all engraved as a cell in a cylinder that is visible to the naked eye. In fact, it makes the side lines of each element suffer.

Engraving is a very high quality industrial printing process, since a cylinder must be made for each color desired in printing, this printing is not economical for low circulations and is usually used for high circulation orders. Intentionally for printing 1 million copies of catalogs, catalog