Classification of Toppan Printing Machines｜Principle of Toppan Printing Machines｜Toppan Printing Operation Process
Abstract: The content printed by letterpress printing machine is the prominent part, refers to the graphic information on the printing plate above the blank area of the machine, mainly serves with the low-end printing of printed materials, such as food paper packaging, supermarket tote bags, horse clip bags, garment bags, etc.. Below, to understand the letterpress printing machine classification, principles, operating processes and other knowledge.
【Toppan Printing Machine】Toppan Printing Machine Classification Toppan Printing Machine Principle Toppan Printing Operation Process
Classification of Toppan Printing Machines
1、Flat press type letterpress printing machine
The flat press type letterpress is a printing machine unique to letterpress printing. The disc and square box presses currently used by printers are of this type. This type of press produces large and even pressure during printing, and is suitable for printing trademarks, book covers, fine color pictures, and other printed materials.
2、Round press type letterpress printing machine
When printing, the circular impression cylinder is in contact with the flat printing plate, and the printing speed is faster than that of a flat press, which is conducive to large-format printing.
According to the form of movement of the impression cylinder, there are two types of rotary letterpress presses: one-turn and two-turn.
3、Round press type letterpress printing machine
There are sheet-fed and roll-fed papers. The printing speed is high, and it mainly prints a large number of newspapers, book interiors, magazines, etc.
Principle of Toppan Printing Machine
The ink feeder of the printing press first distributes the ink evenly, and then transfers the ink to the printing plate by means of the ink rollers.
The graphic part of the letterpress is much higher than the non-graphic part, so ink is transferred only to the graphic part of the printing plate, while the non-graphic part is free of ink.
The paper feed mechanism transports the paper to the printing part, and under printing pressure, the ink from the graphic part of the plate is transferred to the substrate, thus completing a print run.
Common types of letterpress printing: movable type (including clay type and lead type), flexographic. Now only the flexographic plate is still widely used.
★Flexographic printing principle
The ink in the ink hopper is carried on the surface of both the anilox roller cavity and the anilox roller by the action of the anilox roller in the flexographic printing part.
◆The ink on the surface of the anilox roller is scraped off by the action of the squeegee, so that the ink exists only in the anilox roller's cavity.
◆The ink in the anilox cavity is transferred to the flexible printing plate under the action of pressure.
◆Lastly, the ink on the printing plate is transferred to the substrate under the action of printing pressure.
Toppan Printing Operation Process
The printing process using lead plates and photopolymer plates is as follows: preparation before mounting → mounting → printing → quality inspection.
Printing each product needs to be done in accordance with the requirements of the construction order. The construction order, also called a production notice, includes: title, opening, number of impressions, page numbers, printing and binding methods, paper specifications, quality requirements, completion date, etc.
Understand the requirements of the construction order before you can proceed with the preparation work.
First of all, check the plate, paper, ink, check whether it meets the requirements, and then check whether the machine is adjusted to replace the printing package lining, but also the plate binding utensils such as: plate frame, plate support (backing) wood, wood plug, etc. ready to measure the size of each part, you can mount the plate.
Printing according to certain specifications, the sequence of installation to the printing machine, and through the pad plate and other operations, so that the printing quality and specifications of the size of the product requirements of the process called mounting or on the plate. Lead plate mounting process is the most complex, the process flow is: sub-plate and sub-paste → plate placement → pad → pad → nail plate → the whole plate → on the pad → proofing
1、Sub-pages and sub-posts
Sub-page and sub-post refers to the reasonable arrangement of the printing plate page order. General books and magazines commonly used printing methods are reprinting and overprinting.
Where a printing plate with the front after printing, not another plate for the reverse side of the printing, known as reprinting. Load a printing plate can be printed on both sides of the paper products, cut from the middle to get two prints of the same print sheet. The use of reprinting, as long as the order of the page number of the booklet, the printing plate into a suitable book post can be.
Where the first half of the entire payment plate printed on the front of the paper, and then the other half of the plate printed on the reverse side of the paper, known as overprinting. The use of overprinting, you must first divide the printing plate into a number of posts by page number, and then divide a full plate into blocks of the same number of front and back two groups of printing plates.
In addition, you can also be divided into plates in accordance with the binding method. For example: the book using horseback stapling, to the whole book of the front and back page numbers together, and the middle part of the page number of the plate is divided, printed as a separate page, binding and then the pages together.
According to the requirements of binding and folding, the printing plates are placed in the correct position according to the order of the page numbers.
The process of adjusting the pressure on the surface of the printing plate is called pad. The method of pad plate has three kinds of pad, such as under pad, middle pad and upper pad.
When the pressure of more than 1/3 of the layout is too light or too heavy, the paper sheet under the bottom plate or tear off the paper sheet under the bottom plate is called the lower pad.
When the pressure of the layout below 1/3 and above 1 square centimeter is not balanced, the paper is padded under the lead plate or the back side of the lead plate is scraped thin, called the middle pad.
The top pad is done after the bottom pad and the middle pad. First, the ink color of the printing machine will be adjusted to basically match the ink color when printing, hit the upper pad sample. Then on the upper pad sample word by word, line by line to check the weight of the pressure, and then use thin paper strips, in an orderly manner on the embossing cylinder paste, until the ink color is uniform, the pressure meets the requirements.
4、Fixed printing plate
There are more types of letterpress printing machines, and the form of the plate as well as its thickness varies, so the method of fixing the plate is different. For example: flat lead plate in the round press letterpress, with a small nail to the plate stapled to the base plate. lp1101 sheet-fed rotary machine, the plate is fastened to the plate cylinder with screws, and photopolymer plates, generally with double-sided adhesive paper directly on the plate cylinder or glued to the film base wrapped around the outside of the cylinder (film can be removed under the machine on the plate, reducing the downtime when on the plate).
The operation of fixing the printing plate in the correct position according to the requirements of the construction sheet is called plate finishing. Through the whole plate, to achieve the correct size, words, lines, page numbers and other overprint accuracy. There are three methods of plate finishing, scribing sample, tie hole sample, and red set sample. The whole plate of the flat lead plate is in the lower pad, in the pad after the basic fixation of the plate, with the punch plate knocking or moving the position of the plate. Curved lead plate can be loosened to fix the plate screws, moving the plate. Light-sensitive resin plate is glued with double-sided tape, the plate can be gently uncovered, and then re-pasted.
In the installation of the plate, but also to install the printing mark. There are two kinds of printing markers, one is the side gauge marker, installed in the side gauge paper edge, check whether the overprint is accurate, whether there are inverted head, white pages. Another is the binding fold mark (also called post code), installed in the outermost staple of each posting, the purpose of the booklet binding, check whether the book posting more posting, less posting, etc..
After the end of the assembly plate, to make good preparations before opening the printing to print.
Preparatory work includes: stacking the paper to be printed, check the plate sample, open the print sample, check the quality of the text to prevent bad words, broken pens and lack of crosses and other problems. Check whether the size of the specifications meet the specified requirements, check the tightening of the printing plate to prevent the printing plate in the printing loosening.
In the process of printing on the machine, to sample at any time to check the quality of the print, such as: whether on the dirty, walking plate, paste plate, drop plate and other phenomena, found the problem, timely processing. In the printing, but also pay attention to the operation of the machine at all times, found abnormal sound, should be stopped for maintenance.
Light-sensitive resin plate, with a certain degree of flexibility, good ink transfer, printing pressure and ink roller pressure should be less than the lead plate, otherwise tampering easy to make the printing graphics deformation, the appropriate pressure to print a real and not false as good. The use of ink concentration should be higher than the lead version of the ink degree, but the amount of ink can be less than the lead version. Clear the layout ink stain, use a cloth dipped in kerosene or gasoline wipe can, should not use hard brushes.
Features of letterpress prints
● Printing characteristics: The back of the paper of the print has a slight print bump, the lines or dot edges are partially neat, and the ink appears light in the center part, and the raised print edge is heavily pressed and thus has a slight print bump.
● Printing characteristics: The ink color is thicker (ink layer thickness is about 7μm). Can be printed on rougher substrates. Average color reproduction.
● Applications: Trademark, packaging and decoration printing, newspaper printing, etc.
Common printing faults
In letterpress printing, frequent failures include: back scuffing, ink transmission printing, static electricity, etc. These failures affect the printing quality and must be eliminated by taking appropriate measures. These failures affect the quality of printing and must be eliminated by taking appropriate measures.
1、Back scuffing dirty
Printed on the substrate ink, stick to the back of another sheet of print, resulting in scuffing. To prevent the back of the scuffing, generally in the receiving part of the printing machine installed powder spray device, so that fine particles of calcium carbonate dispersed between the sheets. In addition, accelerate the drying of ink, reduce the height of the sheet pallets, between the sheets into the good ink absorption of paper, etc. on the scuffing phenomenon are inhibited.
The phenomenon of tiny droplets of ink, scattered in the air is called "flying ink", also known as ink fog scatter, is the most common failure of high-speed rotary letterpress printing machine. To slow down the "flying ink" phenomenon, you can increase the humidity of the printing shop, the use of conductive inks such as water-based inks.
3、Ink transmission printing
Ink permeability refers to the back of the sheet can see the phenomenon of the front print. Prevent the ink through the print, you can choose the tightness of the paper printing, you can also increase the viscosity of the ink, and properly reduce the printing pressure.
The printing process, the paper is not easy to separate, the receipt of paper on the paper table to receive uneven, or the paper delivery table paper skewed and inaccurate registration, etc., are likely to be caused by static electricity. Eliminate printing static electricity, generally installed on the printing machine electrostatic eliminator, so that the air around the printing press ionization, thus neutralizing the positive and negative static electricity on the paper. Can also be around the printing press or the back of the impression cylinder above, spraying the right amount of water mist to eliminate static electricity on the paper. In addition, increase the humidity of the printing shop, conducive to the elimination of static electricity.