Printmaking
The term printing technology all procedures for reproduction of artwork are grouped together, such as book printing, offset printing, gravure printing, flexographic printing and screen printing. In these printing techniques, different methods are used to transfer ink to a printing material.
The printing techniques explained here can serve the mass production of printed materials by repeated use of a single artwork. This can be offered as a standard product in the so-called " support " in a market (see mass media). "Print" as part of discipline in the data processing does not count in this sense the pressure technique, since the computer printout on a printer along with its (digital ) is made artwork on individual and direct the user's needs in small amounts and the term is generally not as a product on a mass market serves.
- 3.1 high pressure 3.1.1 Indirect printing, Letterset
- 3.1.2 flexo
- 3.5.1 Pad Printing
- 3.5.2 ram pressure
- 3.5.3 frottage
- 3.5.4 Pigmentografie
- 3.5.5 Pochoir
- 3.5.6 embossing
- 3.5.7 Zerrdruck
- 3.6.1 Direct thermal
- 3.6.2 Thermal Transfer
- 3.6.3 Dye sublimation
- 3.6.4 Laser marking
Basics
" [ Printing is the ... ] playing a textual respectively pictorial representation in any number by transferring ink or coloring substances on the substrate by means of a printing form. DIN 8730 "
The preparation of this printing form occurs in prepress. The reproductive technology deals with the reproduction of images and text and create the printing plates for the various printing processes. Images are in the standard printing inks cyan (blue-green ), magenta (red), yellow and white, reproduced as faithfully as possible. In a machine running these colors can be printed one after the other. When printing spot colors, for example in packaging printing, mixed inks are used ready.
The modern printing machines in offset and rotogravure transfer the ink from a printing cylinder on sheets or webs of the printed material. Printing machines in printing processes, such as rotary offset and rotogravure printing can reach speeds between 600 and 900 meters per minute. The machines in the sheet-fed printing are generally slower, but can print on sheets of cardboard, sheet metal and plastic.
Since the 1950s, technological advances in photography and from the 1960s, the production of the artwork changed profoundly in electronics. With the help of the computer, the reproduction process can now accelerate such, ( Helio- Klischograph ) that can be engraved texts and images within a short time transferred directly to the printing plate ( computer to plate ) or on the printing cylinder.
Pressure principles
There are three different pressure principles:
- Surface to surface ( flat against flat)
- Cylinder against surface (around against flat)
- Cylinder to cylinder (round to round)
Surface against surface
This is the oldest of the three methods. With this principle, the material to be printed from a flat platen ( cup) is pressed with great force on a flat, inked printing plate form. The ink is transferred. The disadvantages of the principle are the forces necessary for larger areas and the restricted speed. Platen presses ( presses ) operate according to this principle.
Cylinder against surface
In the 19th century, Friedrich Koenig developed the stop cylinder press. He transferred so that the principle flat against some of the copper printing press from the low pressure to the high pressure.
In principle approximately flat against the contact pressure is performed on the substrate by the rotation of the printing cylinder to the printing forme. In this case, the cylinder rotates firmly mounted about its axis while the printing plate is moved under it in sync with each printing ( printing process ). Thus, the pressure is only within a narrow strip, namely the " tangential " contact area between circular cylinder and a flat printing plate income. In this way, higher speeds and larger sizes in pressure were possible, what was needed especially for newspaper printing.
Cylinder to cylinder
Here is how the printing on two cylinders. The round printing plate is mounted on the printing cylinder. The printing material is pressed through the counter-pressure cylinder, either as a sheet or roll of the printing cylinder and thus printed.
Through the uninterrupted rotation of the cylinder against the cylinder stopping, moving back and re-acceleration is not necessary as in the heavy flat printed form. The pressure forms return in letterpress Schnellpressen is only possible, shut off the pressure. For physical reasons, a substantial increase in the number of revolutions in rotary machines is possible in principle to some around. Modern printing machines work both in sheet and in roll area according to this principle.
The principle around against some can both directly and indirectly effected. Direct printing processes are distinguished by the fact that the image is taken directly from the printing plate to the substrate. Therefore, the printed image must be reversed mounted on the printing form. Examples of a direct printing method independent of the pressure principle are the gravure, letterpress printing and flexographic printing.
In the indirect printing process, the printed image is first attached to an intermediate carrier. The intermediate carrier is flexible and provides the color of the substrate further. For this reason, the print image in an indirect printing process must be the right way. Examples of indirect printing process are the offset printing and pad printing.
Printing process
Printing processes are distinguished according to the following principles
- After the relationship in which the printing elements are printing form, such as flat, high-, low - and print through. According to this feature, the printing process can be distinguished in the DIN 16500 in the main printing processes: High pressure: image areas of the printing plate are higher than non-image areas, such as letterpress and flexo
- Planographic printing (see Lithography ): here are image areas and non-image areas of the printing plate approximately on a level, for example, in offset printing
- Gravure: image areas of the printing plate are lower than non-image areas
- Pressure: image areas of the printing form consist of the openings of a template on a usually colored transparent stencil carrier, a screen made of plastic or metal thread. Non-image areas are impermeable to, for example screen printing and Risographie.
High pressure
The printing press could spread quickly after the improvement of various printing processes and tools by Johannes Gutenberg in the 15th century. The printing press is now called high pressure because the pressure elements are embossed on the printing form.
In the conventional letterpress machines, a fundamental distinction between platen press, cylinder printing press and rotary press. In the platen press, the pressure is carried out, flat / flat, since the flat pressure surface of the crucible is pressed against the flat, usually clamped in the crucible vertically press the printing form. In the printing press cylinder is printed flat against round, that is, the flat shape is drawn in the printing process, as a rule under the round printing cylinder. When the rotary machine printing will round against round by the pressure of the printing cylinder pressure against the round shape, the so-called " round stereo " occurs. When the crucible and cylinder presses the paper feed is always in single sheets, with the rotary machines usually in sheets from the roll. However, in the book printing for special production requirements and sheet-fed rotary machines in use.
From this basic form of high pressure, more pressure forms developed:
Indirect printing, Letterset
Letterset is an indirect high pressure at which the artwork is printed on a page- right cliché. This is bent and mounted on the printing cylinder. The high-pressure plate transfers the print image onto a rubber blanket, the so-called blanket cylinder, whereby said laterally reversed image is formed, which is similar to the offset printing, printed by the blanket to the paper. The printing operation is performed without the use of water, as is required in lithographic printing. This indirect letterpress printing is also called dry offset because of this similarity, however, it belongs to the high-pressure process. Applies the indirect letterpress printing in the packaging industry and the continuous printing.
Flexography
Flexographic printing is a recent high-pressure process in which the printing plate comprises a flexible photopolymer plate. Application areas of flexographic printing are particularly packaging films. Flexography is in close competition with the rotogravure printing can be achieved with the but better quality results. Because of the high printing costs while creating the copper plate of this is uneconomical for small and medium runs. The efficiency is considerably improved in the flexographic printing by the use of prefabricated continuous printing forms. This is to specially developed and adapted to the purpose rubber compounds that work with solvent-based inks, water-based inks or UV inks. After vulcanization on the carrier material (Sleeve ) the print motif by CO2 laser engraved into the surface. This method is called flexographic direct engraving.
Gravure
Gravure printing is a printing method wherein the printing elements by means of chemical or mechanical methods depth are transferred to the printing forme cylinder. The individual, remote from each other by a uniform grid grid dimples called wells. The wells were earlier today produced by etching, engraving by mechanical means of small diamond stylus or laser engraving. During the printing process the printing form cylinder is inked with relatively thin liquid ink and the excess paint with a knife blank from the cylinder stripped. Therefore, the color for printing is left only in the recessed positions of the cylinder; so it only print these games. By high pressure transfer of the ink takes place on the substrate. The ink application amount for an imaging area is determined by the depth of the wells. The chiaroscuro effect of a figure in the low pressure thus depends on the amount of color applied. This fact distinguishes the gravure printing from letterpress and offset printing where the optical result of half-tone images is determined only by the different size of the individual grid points in the respective areas of the image.
The rotogravure, ie the gravure printing forms with cylindrical executed, is economical for large scale print, magazines, decorative films in the furniture industry and wallpapers in very high volumes. The high cost of printing form are compared with low cost in the production run. Especially for the decorative printing is the ability of the seamless endless pressure of significance.
Planographic printing
When planographic printing are printing and non -printing parts in one plane. The principle here is based on the chemical contrast of fat and water. While the printing parts are fat friendly, the non-printing areas are wetted with a film of water and repel the fat ink. The printing, bold games' be applied with ink, crayon, grease pencils or photographic means and take on color. The non-printing areas, however, are prepared hydrophilic, refer to the wetland water and repel the ink in the printing process. The printing areas are referred to as lipophilic, the non-printing to as hydrophilic. For planographic printing include the lithography, offset printing, the light pressure, the Photochrom print and Polyfoliendruck. In this case, the offset is a further development of the rock pressure, by printed indirectly via a rubber blanket. Special forms of indirect pressure to use flat instead of a blanket transfer paper or films.
In practice today sheetfed and web offset printing machines are used. Advantages of offset printing to the wide variety of substrates, and the rapid and cost-effective manufacture of printed forms. Newspapers, large scale print, magazines and packaging are economical high-volume or volumes in web offset printing. Posters, photo books, advertising material or highly finished printed products are produced in small -to-medium run sheetfed economically and with high quality.
Pressing
By the well-known printing method is the screen printing, or silk screening, where the ink with a squeegee -like tool, the rubber blade is pressed through a fine textile fabric through the material to be printed. The printing form is made of a screen printing frame, which is covered with a fabric made of metal or plastic. The fabric bears a pattern of plastic is coated for the preparation thereof, the whole surface of the stretched fabric with a photo-polymer and exposed through a positive film to be printed with the motif. The photo polymer hardens to the non-printing areas, the unexposed material is washed out. When printing, the ink occurs only there through tissue where it has been washed free.
In screen printing a wide variety of materials can be printed on both flat sheets and plates as well as shaped objects, such as bottles, plastic containers and clothing. These are used depending on the material of special inks. Mainly, paper products, plastics, textiles, ceramics, metal, wood and glass to be printed. Compared to other printing processes, the printing speed is relatively low. Screen printing is the only direct printing method, where the printing form has no direct contact with the substrate. There is a gap of 1 to 2 mm, the take-off is known between the two.
In stencil printing without supporting sieve the template itself must be sufficiently strong and is for example made of steel and clamped directly into the frame. As with the possible Stencil print images are limited. This method is used for example for applying the solder paste or glue on mostly rectangular SMD pads on circuit boards. An addition of mesh with print paste components - how is it possible when otherwise almost identical screen printing process - can not occur. In screen printing, however, also non-image areas can be displayed thanks to the supporting wire, which are enclosed completely and without interruption of image locations.
Other printing processes
Other printing processes which are special forms or discharges of these types of printing:
Pad Printing
Pad printing is an indirect deep printing, a combination of intaglio and lithographic printing. The template is using a tampon made of porous silicone rubber of an area, usually a gravure printing plate, transferred to another, such as cups, pens and can therefore also be applied in the well of the deformed material to be printed. Therefore, the pad printing finds particularly in the production of promotional gifts and in packaging printing use, as well in the fine print of model trains or the label of electronic components.
Stamp printing
The ram pressure is one of the oldest printing process in which the individual printing forms are pressed onto the print material. Ram pressure is a flexographic printing process and assign as such the high pressure.
Frottage
The frottage is probably the oldest color printing process. The writings of Confucius ( 551-479 BC) were amplified using this technique. As cliché served an engraved text with marble granite or limestone slab. About this stone pressure plate you put a damp paper which was then pressed with a cloth into the wells of the engraved texts. Subsequently, the paper is coated with ink, wherein the recesses white and remained readable and a kind of negative deduction arose.
Pigmentografie
The pigment photograph is to be regarded as independent graphical method as opposed to pigment printing. When Al Bernstein in USA the 1970s as trace print launched printing technology, the individual printing plates are cut and engraved in the positive-negative method, in contrast to the pochoir, very fine lines and dots can be printed. During the printing process, the ink is manually brushed by the stencil sheet and then fixed.
Pochoir
When called pochoir, stencil or even stencil art, graphics and texts may be applied by means of templates and is considered one of the oldest industrial color printing techniques. The method was used in 1796 in Epinal, France. Today there is still printed in this technique. Pochoir occurs today in the street and is to be regarded as a subspecies of graffiti. This printing process can be broadly associated with the screen printing.
Embossing
When embossing patterns are embossed into the material to be printed. If this is done without color is also called blind printing, blind printing, blind embossing or embossing. The method is used for example for book covers, greeting cards and wallpaper use. Blind pressure there was in the form of cylinder and stamp seals in the 4th millennium BC in Mesopotamia and Egypt.
Zerrdruck
The Zerrdruck is a method in which an image of a cliché to a plasticine on silicone rubber based transfer, deformed and then printed as a distorted image. With this technique developed in 1967 prior to the digital image processing, it was possible to produce distorted images.
Electronic printing process
Electronic printing process, and Non - Impact Printing or NIP method called, are methods without explicit printing form and designate a constantly growing number of color thermal printers, plotters and inkjet printers. Laser printer or line printers are not counted among the NIP process since there can not be the ink transfer without pressure applied to the paper. Type printers are, for example, so-called transfer through the printer, and a basic mix of letterpress and screen printing; they have mold components (types), but do not exhibit the typical total constellation form a printing press. The old dot-matrix printers, also called dot matrix printers, also falls into this category. The classic laser printer can be expected to the electronic method of lithographic printing. It has the image of the print image on the drum, the toner, a printing plate, even if only temporary.
Direct thermal
In direct thermal printing, the printing result is achieved by selective heat generation rather than by mechanical stop or pressure. There is a temperature-sensitive special paper use, which blackens when heated. The thermal printing is widely used in cash registers, and was formerly used in fax machines.
Thermal transfer printing
Thermal transfer printing is the evolution of direct thermal pressure, especially in the area of the CD and DVD printing. For this purpose, a special printer is used, the mentioned by heating of the print head, the color of a color-bearing polyester film, ribbon, separates and transmits to a specific retransfer. From this retransfer film in a film is fused to the print medium. Through this intermediate transfer high resolution is possible and the pressure can be all over. Therefore, even small quantities in photorealistic quality can be printed.
Dye sublimation
The dye sublimation printing has also been developed further by the thermal transfer printing. The difference is the transfer of the ink from the carrier film to the paper by sublimation. Because the color is short in gaseous form, is true tonal gradation without screening can be generated. A weakness of the thermal transfer printing at photo printing could be eliminated. However, the consumption cost of transfer films are very high, so that these devices could not hold on the market. In recent times, the printing process re-established for small-format photo printers as accessories for digital cameras.
Laser marking
The laser marking material to be printed is treated by a high-energy laser beam. It may, depending on the material and procedures that lead to chemical changes, such as burning, discoloration, or even a material removal. The laser inscription is now used widely for labeling electronic components or keyboards. A particular advantage is the ability to create very small, machine readable fonts. Another advantage is that, for example Plexiglas plates can often be cut with the same laser and labeled.
Ink
Printing inks are adjusted in their composition and in their properties to the printing process. In all planographic printing method and printing paste with high viscosity inks. In flexo and gravure printing, however, low-viscosity, low-viscosity paints are used. In screen printing the selected colors and their properties from the specific purpose dependent. The historical letterpress printing ink of the black art was soot, which was dispersed by vigorous Einspachteln in the selbstaushärtende linseed oil. Modern inks are highly complex mixtures.