Offset printing is a printing technology using a printing form. offset and digital printing are the most common technologies in the printing business. This printing technology is more complex than digital printing but also more common, we will figure out its features, production stages and advantages and disadvantages below.
The process of printing with the offset technology.
It consists of the following stages: design, preparation of the plates, printing, postprinting processing. At the design stage, your layout is spread on 4 layouts which consist of only one color according to CMYK. After that, the print forms are made, 4 pieces, 1 for each color. If you need two-sided printing, you need 8 forms, 4 on each side. When the plates are ready the preparatory process continues. To do this, 1 plate is fixed on the printing shaft and one of 4 inks is printed according to the CMYK. Printing equipment is from 1 to 8 shafts. After printing 4 colors, a full-color image is obtained, the entire offset printing consists of mixing 4 colors (cyan, magenta, yellow, black). After printing, the sheets of printed material are cut, folded, bent, fastened and the final product is obtained.
Now let's look at some more highlights. Printing plates are made from the plates with a thickness of about 0.3 mm. Most often they are made of aluminum but there are other metal alloys. Then the plate is exposed to ultraviolet radiation either positively or negatively, both methods are used in the way it is more convenient for anyone. With a positive creation of the plates, they serve 2-3 times longer but there is a risk of ingress of the dust particles or other elements along the edges of the printing form. There is also a way to create the plates by burning the laser; it is used for printing with the dry offset, whereas the first two options are for the wet offset.
After this, printing is done, the speed of which depends on the equipment and the number of the shafts on it. If the machine is on 1 shaft, for the for full-color printing from 1 side you need to drive off the printed sheets 4 times and reconfigure the machine the same number of times. If the machine has 4 shafts, each side can be driven away in one set of setting and printing. Why do the offset machines require 5, 6 and so on shafts? Because with this technology, you can print on the exact color of Pantone or use a selective varnish, gold or silver paint, and other special effects. For this, additional forms are made, which are used on 5 and the other shafts. They can be used on a single machine but you can imagine the speed of printing and the number of reconfigurations.
At the end of the production process, printed sheets can be laminated, cut to the desired dimensions, creasing or folding can be made, holes can be pierced, make figured cutting and fasten into a multi-page product with one of the ways of bonding. But all these procedures are not directly related to the offset printing, they are also used in the digital printing.
Types of the offset printing technology.
They distinguish two of them: dry one and traditional one. The dry offset appeared relatively recently, in 1982. Its difference from the traditional offset is that it does not need to moisten the shafts which facilitates the configuration of the printing equipment. The difficulty is that for the dry offset you need the special paints with a complex set of the elements included. Well, also the production of platinum is done either by ultraviolet light or by laser burn-through. I can not unequivocally say which method is better, everyone chooses what is more convenient for them.
According to the type of the equipment the sheet and roll types are distinguished. The sheet one is much more common and is used in 90% of cases, and the roll one is suitable for printing of the newspapers, magazines or other products which can be immediately folded. There are many manufacturers and models of the offset equipment, their differences can be read in detail in the specialized resources. In general, the difference between them is in the format of a printed sheet, usually A3 machines, there are A2, A1 and more, for example, 135*190 cm which is approximately B0 format. Also in the printing speed, there are faster and slower machines. Another important difference is the number of printing rolls, the more there are, the easier and faster printing occurs. These are the main points that need to be understood because different printing is conveniently made on different machines. There is no universal equipment on which it is profitable to make all types of printing products.
And so let us summarize and draw conclusions about the offset printing technology.
- Fast print speed of medium and large runs;
- The best print quality;
- Ability to print on any type of paper, stickers, film;
- The more circulation is, the cheaper the print.
- The cost of small runs, due to the preparation;
- The inability to make a probe;
- It is impossible to make an urgent circulation in a couple of hours, due to the preparation;
- It is impossible to make personification.
In general, this is the basic information for understanding how the offset printing is done, which stages of production there exist, its features with advantages and disadvantages. But there are many subtleties, nuances and trifles that are known only to the experienced professionals in the field of the printing production. We can offer you to place your orders for the offset printing with us, we will try to find the best equipment for all stages of production to satisfy you in terms of both price and product quality.