29 printing tips you should know
Abstract: Printing Machinery Knowledge Primer - Features - Classification Chapter: The article mainly introduces the meaning of printing quality, offset printing and other printing differences, offset printing process principle, the ph value in the wetting solution and other related knowledge. 29 you should know the printing tips 1. What is the meaning of quality? What is the meaning of printing quality? The quality is also known as quality, reflecting the product or service, to meet the explicit or implicit need for the sum of the characteristics and features of the ability. The quality of printing refers to the technical quality of the printing reproduction process, including the absolute quality and average quality. 2. What are the main quality requirements for color printing? The register is adequate, ink
Abstract: Printing Machinery Knowledge Primer - Features - Classification Chapter: The article mainly introduces the meaning of printing quality, the difference between offset printing and other printing, the process principle of offset printing, the ph value in the wetting solution and other related knowledge.
29 printing tips you should know
1. What is the meaning of quality? What is the meaning of printing quality?
Quality, also called quality, reflects the sum of characteristics and features of a product or service, the ability to meet an explicit or implicit need.
Print quality refers to the technical quality of the printing process in the reproduction of printed materials, including absolute and average quality.
2. What are the main quality requirements for color printing?
The overprinting is accurate, the ink color is even and vivid, the layers are rich, the dots are clean and full, the field is flat, the text is clear, there are no broken strokes, no obvious marks, no greasy and dirty, no paper hairs, no ink skin and other phenomena and the authenticity of the original is faithfully restored.
3. What are the differences between offset printing and other printing?
①Use the basic principle that oil and water are insoluble to complete the printing:
②The blank part is basically on the same printing plate surface as the graphic part and is selectively adsorbed water and ink;
③ is through the intermediate (rubber blanket cylinder) to transfer the print:
④ is through the dot size to present the order tone.
4. What is the process principle of offset printing?
Offset printing is the use of the basic principle that water and oil are not compatible to achieve printing results. When printing, water is applied first, so that the blank part of the layout absorbs water, while the image part repels water. When ink is applied, the blank part repels the ink while the image part adsorbs the ink.
5. What does the ph value in the wetting solution refer to?
The ph value is the value (concentration) of the acid and base content contained in the wetting solution, and the negative logarithmic value of the hydrogen ion concentration is used to indicate the acidity and alkalinity of the solution. ph=7 is a neutral solution, ph>7 is an alkaline solution, ph<7 is an acidic solution.
6. What range should the ph value in the wetting solution be controlled in production?
For the ps version of the wetting solution in the ph value, generally controlled in the raw between 5 to 6 is appropriate.
7. What is the effect on product quality if the ph value in the wetting solution is not properly controlled?
Strong acidity: easy to cause the printing plate flower plate, network becomes smaller, reduce the printing plate printing power, ink is easy to emulsify, causing the print is not easy to dry, the back of the product sticky and other quality ills.
Weak acidity: printing plate network is easy to paste, easy and dirty, resulting in paste plate, nasty, etc.
8. What are the characteristics of alcohol wetting?
①Good wetting performance and good spreading performance on the layout;
②Because alcohol has a certain volatility, the layout of water transfer to the rubber blanket, the water has a certain degree of evaporation, so the paper will reduce the water absorption;
③ alcohol in the evaporation, can take away a lot of heat, so that the layout temperature is reduced, to ensure the liquidity of the ink performance.
9. What is the role of wetting solution in production?
①Make the blank part not dirty and greasy (not grease sensitive);
②Make the blank part keep good hydrophilic property by hydrophilic colloid and organic acid;
③ through surface active substances and surfactants, so that the blank part of the layout only needs less water, so that the blank part can be protected, which is conducive to the water-ink balance;
④ through the buffer solution (the same ionic effect) to make the wetting solution ph value stable.
10. When printing, what is the effect of the size of the page moisture and product quality?
Printing operations in the layout of water control dysfunction; when, resulting in large water, easy to product ink color too light, ink lusterless, color color color is not bright, the plate is easy to spend plate, ink is easy to emulsify, while the paper will cause expansion and deformation, resulting in inaccurate overprinting and other quality defects; and small water, easy to make the layout dirty or greasy and dot appear and even and paste off and other quality defects.
11. What is the meaning of "water and ink balance" required in daily production?
Water and ink balance is to adjust the supply of wetting solution under certain conditions, so that the amount of ink emulsion control in the smallest range, with the smallest amount of water and printing plate image should be the amount of ink ink counterbalance.
12. How do I achieve a balance of water and ink in my work?
①The printing plate should have good hydrophilicity and lipophilicity, with a good stable base and adsorption power.
②To have a good coarse and uniform sand mesh mesh, a good water storage function of the plate, and to have a strong resistance to mechanical wear performance.
③The workshop has a good production environment, and the workshop temperature and humidity are relatively malicious.
④The machine runs evenly and normally, not fast and slow.
⑤ To have good paper and ink.
⑥The thickness of the ink layer of the graphic part of the printing plate is 2-3 um, the blank part of the water film thickness is 0.5-1 um. The amount of wetting solution contained in the ink is 15% to 26%, the maximum does not exceed 30%.
13. What is meant by gauge line?
For the plate, printing, cutting, binding required and prefabricated various shapes of the line called the gauge line, also called the specification line.
14. What are the common gauge lines?
There are common gauge lines such as corner lines and drag lines, cross lines for overprinting, folding lines for binding, burr lines and net cutting lines for cutting.
15. What are the main factors causing overprint inaccuracy?
There are generally four main factors that cause inaccurate overprinting:
① improper operation of the process caused by inaccurate overprinting (generally refers to improper handover time and position when the machine is commissioned);
② mechanical equipment wear caused by inaccurate overprinting (general wear parts such as bearings, gears, bushings and other related other parts, etc.):
③ material reasons (related to the texture of the paper and silk skein, etc.);
④ inaccuracy of the collotype (the soft piece of small patch before printing is not correct);
⑤ plate deformation (due to excessive pulling force when loading the plate, resulting in plate deformation);
⑥ other aspects such as sudden changes in the weather caused by the production environment, temperature and humidity changes caused by serious deformation of the paper, causing inaccurate overprinting.
16. What is the difference between a four-color machine that is not allowed to overprint and a single or two-color machine that is not allowed to overprint when printing?
Single, two-color machine overprint inadmissible is after the color and the former color have circumferential and axial overprint; and four-color machine overprint inadmissible means four-color once printed down overprint accurate, but before and after the print sheet gauge line position is not in the same position, the print sheet specifications are not uniform (circumferential and axial), that is to say, the graphics bite or side gauge at the white edge size difference, generally not easy to find.
17. In the case of j2108 or j2205 offset presses, how many times is the paper handed over from the delivery rack to the front gauge and then to the receiving table when the printing is completed?
① The handover when the paper reaches the front gauge;
② the handover between the front gauge and the side gauge;
③ the handover between the side gauge and the paper delivery nibble;
④ handing paper nibs and embossing nibs of the handover;
⑤ embossing teeth and pick up the handover of the paper teeth.
18. What are the common forms of pre-determined positions?
There are two forms of upward swinging front prescriptive position and downward swinging front prescriptive position.
19. What are the common forms of paper delivery devices?
There are two types of paper feeders, the upper swing feeder and the lower swing feeder.
20. What are the characteristics of the upper swing front position?
The upward swinging front gauge blocking plate can only enter the renewal positioning position after the tow of the front sheet has all left the paper feeder, and the next sheet is positioned for work, the positioning time of which depends on the roller diameter and the paper width size.
21. What are the characteristics of the lower swing front position?
The front gauge does not need to wait for the front sheet's trailing paper edge to leave the feeding board to enter the positioning position, and then it can work on the next sheet to position. Therefore, under the same conditions, the positioning time is longer and the positioning stability is better with the swing-down front gauge.
22. What are the characteristics of the upper swing paper delivery device?
(i) The motion trajectory resembles a drop closed curve, which is accomplished by using an eccentric device;
②To enable the paper delivery device to avoid the surface of the drum when it returns.
23. What are the features of the lower swing paper delivery device?
①Fixed-center swing, the trajectory is in the form of circular arc:
②One more paper catching roller than the upper swing type paper delivery, with eccentric structure to avoid the paper delivery device from touching with the roller when it returns.
24. What are the characteristics of the movement of paper delivery teeth in daily work?
① paper delivery tooth row is at rest or relatively at rest when receiving paper at the front gauge;
② paper delivery speed is smooth acceleration (range from zero-one roller surface line speed);
③ paper delivery tooth row and roller in the same all points for paper handover, and this time the two movement in the opposite direction, but the surface speed is equal, that is, at a relative standstill to complete the handover.
25. What are the characteristics of the movement of the high-speed paper splitting mechanism?
①Adopt the structure of one eccentric two cams to reduce the force on the paper dividing shaft and have good stability;
②Adopt air-controlled structure, using internal air pressure and change of Song to control the drop and lift of the nozzle, so that the paper suction movement is correct;
③Adopt guide groove structure to complete the movement of paper feeding nozzle, which can control paper skewing;
④Adopt rotary air distribution valve, valve spool and valve seat with high precision, and also adopt lap type structure, which is easy to disassemble the spool shaft and paper dividing shaft.
26. What are the requirements when handing the paper nibs and embossing nibs synchronously?
① Completion of the nibbling handover time to ensure that:
② no breakage of the paper edge mouth at the time of the nibbling handover;
③The effect of the nibbling handover should ensure that the overprint is accurate enough.
27. What is meant by printing pressure?
The ink on the graphic part of the printing plate is transferred to the substrate by the positive pressure called printing pressure.
28. What are the forms of printing pressure?
① surface pressure indication; ② line pressure indication; ③ compression amount indication; ④ contact area width indication.
29. What is ideal pressure?
The ideal pressure is the one that uses the minimum amount of force to obtain the required dot size to match the original.