Today rotogravure printing uses a laser engraved impression cylinder with tiny cells capable of preserving ink, the size and sample of which reflect the particular image. These cells are pressurized to transfer their ink immediately to the substrate by means of a mixture of stress and capillary action, thereby generating the diffused image.
So, let’s get to know each other in detail.
- Engraved cylinder
- Printing cylinder
- Ink foundation
- Doctor’s blade assembly
- Engraved cylinder
The image carrier of the gravure printing machine is commonly known as the engraved cylinder. It is made from hollow steel cylinders and is galvanized with nickel and copper. The doctor blade is coated with a layer of chrome to protect the image cells.
There are three types of cylinder engraving methods
- Chemical etching
- Laser engraving
- Diamond stylus engraving
A negative film is applied to a non-image area which is commonly referred to as a resist. During engraving, it resists the chemical from entering non-image areas.
This process uses a printing cylinder that has been laser engraved with tiny cells capable of preserving ink, pattern, and size, which reflect the required image. These cells are needed to move their ink directly onto the material by a mixture of pressure and capillary action, this is how the image is printed.
- Printing roller
A rubber sleeve is placed on a steel mandrel.
Its main purpose is to press the substance against the impression cylinder.
The inking system contains an ink pen, ink tank and ink pump with ink supply and return hoses.
- Ink foundation
In the gravure printing process, two types of ink are used.
- Water based ink
- Solvent based ink
Water based ink
These types of inks specifically used for gravure printing and product packaging require longer disclosure time and higher temperature in order to remove low vapor pressure constituents and water. As mentioned in the next section, Flexo and Gravure inks are very ordinary and the component is mainly carbon copy. Maybe need a pollution control device.
Solvent based ink
Gravure inks are fluid inks with a very low viscosity which allow them to penetrate the engraved cells of the cylinder and then to move on the material.
In order to dry the ink and remove the solvents, which usually return most of the solvent, the paper is passed through gas or electric dryers.
Before the paper passes to the next rotogravure printing station, the ink will dry in advance.
This is mandatory because wet inks cannot be overprinted without coating or smearing. Thus, after each gravure printing station, large volume air dryers are installed.
The solvent-laden air passes through either a solvent vapor incinerator or a solvent recovery system. To absorb the solvent, a standard recovery system uses activated carbon beds.
By steam, saturated beds are revived. They liquefy and by gravity the water and the solvent separate.
Using this process, over 95 percent of ink solvents can be recovered using this process. By incineration, the solvents can be reprocessed or demolished.
- Doctor Blade
The doctor blade is a device which separates the ink from the unengraved part of the gravure printing and also separates the extra ink from the engraved part.
- Drying system
Composed of a chamber that dries the ink once it is on the material and precedes it until the next gravure printing unit.
The capacities of the dryer are dedicated according to the print speed required, the type of solvent or water-based ink and the set ink volume.
The gravure printing process serves the decorative printing markets. The rotogravure printing machine offers precise design and high manufacturing standards. This gravure printing machine offers exceptional reliability, lasting value and the highest production quality. In the market, there are different manufacturers of rotogravure printing machines, but among them, different manufacturers offer machines of different design and quality.