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Flexography, silk-screen printing or UV a press?! How to make a correct choice.

This article is written to know about different technologies of printing to understand this process itself, what clauses of expenses exist, and certainly to find out the final cost price of printing and to consider its difference depending on circulation. Certainly, in one item it is impossible to consider absolutely all nuances of the given technologies, therefore we shall briefly review on bases, underline their advantages and disadvantages, and in the end we shall make comparison.

Flexography

The flexography is a way of a high direct rotational print with elastic (flexible rubber, photopolymeric) relief printed forms fixed on master cylinders of the various sizes. By means of the roller or screened cylinder (transfer of the image by points) cooperating with squeegee (the tool for drawing a film), forms cover with liquid quick-drying (water-soluble or on flying solvents) printed paint and transfer it on a material of any kind, including and not absorbing materials. The image on the printed form is mirror-like.

Features of printing

• It is applied at medium circulation printing (from 1000 copies);
• Demands long pre-printing preparation (few hours):
  • preparation of a file in specialized programs for example, in Photoshop (as work occurs to a rough raster - up to 150 lines/inches therefore at printing there are some problems - fine details lose clearness). For this reason it’s necessary to do a quantity of coloring test;
  • manufacturing flex-forms (irrespective of a way of printing(analog or digital) after manufacturing time for washing and drying of the form is required)
  • manufacturing of squeege knife and cutting (if it is required).
• A press by specialized machines
• Ample opportunities for application of various finishing technologies: varnishing, masking, foil stamping , etc.

Stages of technology:

1. Preparation of a file, design.

In flexography quality of an end-product in many respects depends on design. As use forms on the basis of polymer, there are certain restrictions on a lineature (quantity of lines on inch). Flexography works with more rough rasters, rather than offset or an intaglio printing, and usually a lineature does not exceed 150 l/inch. Hence, at printing of unprepared to a flexography images there can be problems. The fine print, especially sets with notches, loses clearness. At exhibiting from a negative of semitones it is difficult to transfer details in extremely light colors, etc. For a flexography there are no standards on structure of paints, therefore to reach high quality much more difficultly, than at other kinds of printing. Most of all time leaves on adjustment of correct transfer in the most light areas. Often a reliable reference point can be coloring test only which prints on the special equipment. Therefore the ready design always have to be adapted under the concrete flexo-machine as practically everyone has the features

2. Flex-forms manufacturing

Flex-forms are made by two ways - analog and digital. For a digital way of manufacturing there are special machines. An analog way - use of special chemical for drawing the image. After manufacturing it is washed out and dried.

3. The press.

Is carried out on special machines. There is a set of configurations of flexo-machines with various widths of a press (up to 2500 mm) and speed up to 250 m/mines. Besides, many models have a section structure that allows adding various finishing technologies. The press is finished and does not demand additional actions.

Let's consider advantages and disadvantages of a flexography.

Advantages:

• The wide range of materials that can be printed on;
• Can be used to press on very thick materials;
• Relative profitability on wide enough range of circulations;
• The opportunity of application of water basis paints that carries a flexography to ecologically pure manufacture;
• At the certain circulations very low cost price;
• Press with metallized paints;
• The opportunity of joining up after printed processes (lamination, cutting, gluing) in one line.

Disadvantages:

• Long pre - print preparation demanding certain expenses;
• Great value to spread the points of a raster;
• Reproducing difficulties in shadows and high colors, a problem of a press of soft color transitions;
• Impossibility to press fonts with small size, especially reverse;
• High cost price at small circulations;
• Quality of a press varies from the machine to the machine, that is the design is necessary for adapting to each machine;
• Absence of industrial standards.

Silk-screen printing

Silk-screen printing - a kind of screen print in which the image is put by oil or water paints on a grid (from silk or other strong matter), tense on a framework (the sites of a grid corresponding to spacing of a composition, cover with impenetrable structure for a paint); when printing the paint is pressed with squeegees through apertures of a grid on perceiving surface.

Features of a press

• It is applied at medium circulation press (from 1000 copies);
• Aggregate of several technologies: technology of a tension forming frames, technology of a choice of the most suitable screen cloth, ink emulsification of printed forms, use of many opportunities of a press, a choice of paint, drying by a special method, etc.
• Demands long pre-printing preparation (within a few hours):
  • Manufacturing of clichщs, depending on quantity of colors which will be used (for manufacturing a quantity of special materials is required: emulsion, the retouch, washing solutions, etc.), after manufacturing or washing drying of a clichщ is required)
  • Manufacturing of a squeegee and frame on which the clichщ will stretch;
  • the Press on specialized machine tools (in some cases it is possible to collect such machine tool yourself);
  • The press is made on colors-1 after another and between drawings its need to dry out the previous color.

Stages of technology:

1. Preparation of the image

2. Manufacturing of a clichщ.

The Image which it is necessary to print is painted in a positive on a transparent film by means of the phototypesetting automatic device. Sometimes the tracing-paper and the usual laser printer are used, but in this case optical density of the received film appears too low, and it should be raised by special aerosols. After that a film together with the printed form covered by a special photosensitive solution, and place for some time in the exposition chamber. The lamps of a ultra-violet luminescence shine the form through a film owing to what the solution on not closed by black sites of a film surface of the form hardens. After exhibiting, by the water-jet unit from the form wash away not hardened rests of a solution. After such processing the form (the sieve of thin silk or synthetic strings) represents a clichщ with the necessary image.

3. Manufacturing of a frame.

The frame is made of various materials; wood is frequent one, which certainly has a number of problems because of specificity of properties of wood (swelling from water, defects from presence of knots, etc.)

4. Squeegee’s manufacturing.

5. Stretching a clich on a frame.

From this stage depends, whether there will be distortions on the sealed image

6. Drawing of the image

After drawing the image -time for drying is required. At drawing several colors, after drawing separate color drying is required and following color only then is put. Drawing can be made manually, and by special machines.

Let's consider advantages and disadvantages of silk-screen printing.

Advantages:

• The wide range of materials which can be printed on;
• Paint layer is thicker in comparison with other types of a printing, so the image is steady against external influences;
• Simplicity - at small circulations drawing can be made manually, without expenses for purchase of the expensive equipment;
• To start up a business 200-300 $ will be enough

Disadvantages:

• Long pre-print preparation demanding certain expenses, sets of account materials and time;
• The press of circulation less than 100-500 copies is not profitable;
• Low durability of a cliche and squeegee, that delivers problems at big circulations;
• Distortions in case of a bad stretch of a cliche on a frame;
• Drying, both at manufacturing cliches, and during drawing the image;
• The Low resolution which depends on the size of a cell of the material used at manufacturing of a cliche;
• The research problem is - how to pick up paints which "keep" on new materials.
• Ecologically unsafe way since ink contains chemical solvents, evaporate.

Digital UV- printing

Digital UV printing - a kind of a digital printing at which the press is carried out on the basis of piezoelectric jet technology. At this kind of printing ink cure (polymerize) under action of UV-radiation.

Features of a press:

• It is applied at small and average circulations (from 1 exclusive copy);
• The press is carried out by means of special program RIP and on special printers;
• Does not demand long pre-print preparation; the ready file can be printed practically at once.

Stages of technology:

1. Preparation of the image.

Specialized programs (- Photoshop, Corel Draw, etc.) are applied for preparation of the image, as usual it does not takes much time.

2. The press.

The image by means of specialized programs (RIP - programs) sends on the printer which carries out a direct print on a material. Also on the printer instant drying is carried out. After printing, the image does not demand additional actions and is finished (the cutting of the image from leaf of a material sometimes is required).

Let's consider advantages and disadvantages of digital UV- printing.

Advantages:

• The wide range of types of materials that can be printed on;
• High quality of printing;
• The direct press (except for some cases);
• Absence of harmful evaporations;
• Instant drying;
• UV ink have a low transparency therefore it gives fully saturated color;
• Ecological compatibility allows using it in interiors and the goods with the raised sanitary requirements.

Disadvantages:

• It’s not profitable at medium and big circulations;
• High cost of printers.

Conclusion.

Now let’s compare expenses at different fabrication stages and put it in the comparative table. All data approximate also are calculated on 4 color print on 1 square meter, cost of the equipment is not considered:

* - The big circulation lowers cost price (For example, at the order 10 000 - 27.3 rub and less for square meter)

Let's consider all these types of print at various circulations.

1. From 1 up to 50 copies. In this case it is profitable to print by means of digital UV technologies as it does not demand labour-consuming pre-print preparation. The circulation will be quickly printed, and under the lower cost price as the basic expenses will go only on the charge of paint. At flexography and silk-screen printing an expense for manufacturing flex-forms, clichщs and other auxiliary tools will be high and, accordingly, the final cost price too.

2. From 50 up to 500 copies. At such circulation it is possible to use both silk-screen printing and digital UV - printing. The more quantity of copies, the silk-screen printing will be cheaper. But it is necessary to note, that the resolution, and quality of the received image, on UV - printer will be much better (!), than that at silk-screen printing.

3. More then 5000 copies. At such circulations it’s better to use flexography and silk-screen printing. And if to choose between silk-screen printing and a flexography the preference is given a flexography as flex-forms are more durable in comparison with clichщs, but silk-screen printing in some cases allows working in «house conditions ".

UV-printing is not absolutely convenient. First, time spent for a printing is high, and besides UV -printing will lose in the cost price.

We hope, now you can make the right choice!!!