Overview of the most popular offset printing proce

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Overview of offset printing production process

characteristics of offset printing production

1. Using the advanced method of modern graphic information processing, use the eye tone to show the gradation and color of the original, and the gradation and color reproducibility of the replica are better than that of the host

2. Based on the basic principle of immiscibility of oil and water, water first and then ink on the same plane of the printing plate, so as to achieve the balance of water and ink, so that the ink transfer of pictures and texts, and the pictures and texts are clear and complete

3. Take the blanket as the media, and the substrate obtains pictures and texts from the blanket, so that the ink can be fully transferred. I hope all operators can remember that the reduction effect is good, and can maintain the printing resistance of the printing plate

4. The plate is made of metal aluminum and has a wide range of resources, especially PS plate (precoated photosensitized plate), which has fast plate making speed, good quality and high printing resistance

5. At present, offset lithography is developing towards multi-color printing, with fast printing speed, high degree of automation control, short printing cycle, and printing products to further create business cards that represent the country to participate in international competition, with good quality

offset production process

offset production is the process of color manuscript reproduction, which includes plate making, printing and post press processing

(1) plate making: that is, the process of copying into a printing plate according to the original. The process flow is shown in figure 2 1

1. Image plate making and text typesetting are classified, and then the text and image are combined and copied into the print original (negative)

(1) image plate making: the general term for copying image originals by manual, photographic, electronic and other plate making methods. Its technological process is:

① color separation: the process of decomposing the color manuscript into monochrome versions. At present, the traditional photographic color separation method has been phased out. Most of it uses electronic color separation, which uses electronic scanning to decompose the color manuscript into monochrome versions

② copy: in reproduction technology, the process of reproducing pictures and texts by contacting and exposing negatives with photosensitive materials. Common equipment includes continuous drying machine, copying machine, etc

③ large version: put together negatives such as words, charts and images according to printing conditions and format to form the original version for printing

④ printing: the process of copying the pictures and texts on the original printing plate to the printing plate by contact exposure through the printing machine. PS version is generally used for printing plate

⑤ proofing: the process of copying proofs from the graphic information of the assembly. The proofs of proofing are divided into three types: monochrome, overlapping and panchromatic. Proofing can be carried out on proofing machine or offset press

(2). Text typesetting: the process of composing the text manuscript into a specified format according to the design requirements. Computer typesetting technology is mainly adopted. The process is as follows:

① first input the text with a computer terminal, group the version, and issue the proofing

② output the negative film with the laser Phototypesetter after proofreading

③ the negative obtained by Phototypesetting can be directly exposed to the printing plate, or according to the requirements of layout design, the negative can be made up and copied, and then exposed to the printing plate for proofing and printing

2. DTP (desktop publishing system) color desktop publishing system: input images and words into the computer, use the computer to process and process images, draw graphics, and then combine graphics, images, and words into a whole page layout, and use the laser Phototypesetter to output this electronic layout to become the original print

3. CTP (computer to plate) computer direct plate making: with the further development of printing technology, it can not only make plate directly from the original, but also realize the direct interface between computer publishing system and printing machine, which can be completed in one step from the original to printing

(2) printing: the process of using a printing plate to transfer the graphic information on the original to the substrate. It starts from receiving the prepared printing plate to printing the finished product. This process can be divided into four parts: prepress preparation, trial printing, formal printing and printing completion

1. Pre press can also start the function preparation of early warning and troubleshooting at any time: including getting familiar with the production construction sheet, checking the printing plate, preparing the printing materials, pre-adjusting the machine, etc

2. Trial printing: including surface treatment of printing plate, correction of edition position, adjustment of ink and so on, until the trial printing sheet can meet the requirements of sample signing

3. Formal printing: including sampling inspection during normal printing, supplement of wetting liquid and ink, control of ink balance, inspection of machine operation, troubleshooting of printing faults, etc

4. Completion of printing: including the storage of semi-finished products and finished products, the cleaning and maintenance of offset press, the maintenance of printing plate and blanket, etc

post press processing

a production process that enables printed matter to meet the required shape and performance. For example, books and periodicals should be bound, inspected and packaged. Various packaging products are processed after printing according to different requirements, such as die cutting, bronzing, gluing, box making, etc

basic knowledge of offset press

(1) origin, current situation and development trend of offset press

offset press is the main equipment of offset lithography. It was first developed by American William Invented by bel. Later, caspor Hermon, a German American, built the first offset press with three rollers (plate cylinder, blanket cylinder and impression cylinder) in Germany from 1906 to 1907. Today, the basic structure of offset press is still three rollers. Although the printing machines produced by various printing machine manufacturers have their own characteristics, the general structure, operation method, operation procedure and paper direction of the printing machine are basically the same

at present, there are many enterprises producing sheet fed offset printing machines in China, among which the product varieties of Beijing People's machine factory are more, and the quality is relatively stable, such as J2108, J2205, pz4880 split four-color offset printing machines, which are representative, and the maximum printing speed can reach 11000 sheets/hour. Imported offset printing machines are the most representative of Heidelberg series offset printing machines in Germany. Others include German Roland, Japanese Komori, Mitsubishi offset press, etc

the level of imported sheet fed offset printing machines has taken a big step forward in the 1990s. Mainly reflected in:

1. The printing speed is increased to 15000 sheets/hour

2. Due to the improvement of automatic control level, the pre adjustment time before printing is greatly shortened

the preset time was usually about 2 hours, but now it can be reduced to 15 minutes

3. The degree of automation is greatly improved, which can realize the full automation of the entire printing machine operation and operating system from paper handling to the end of printing

the future development trend of printing machine is still the integration of machine, electricity, light and sound, and finally realize full automation

2.2.2 classification of sheet fed offset press

1. Classification by purpose. It can be divided into offset press for printing paper, proofing offset press, iron offset press, etc

2. Classification by printing color number. It can be divided into monochrome, two-color, four-color, five color offset printing machines, etc

3. Classify according to the size of the paper. It can be divided into small full sheet, full sheet, folio, four open, eight open offset press, etc

4. Classify according to the printing surface of the printed matter. It can be divided into single-sided printing and double-sided offset printing machines

source: Printing Technology

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