At present, in some small cities and township printing enterprises, the application of offset printing machines is very common, but most of them are monochromatic old models, namely PS2101 offset printing press. Due to the low level of automation, it is entirely up to the operator to master the entire printing process. In the offset printing process, various kinds of printing often occur, so that those who lack experience are even baffled. I talk about some experience for peer reference.
First, the blanket is not installed caused by printing failure Offset machine blanket is a very detailed work, not well installed can cause a lot of failure, such as the printed end of the product is a real one end, ink dark before and after, Within 30cm of the mouth, the strokes became thicker, and the product appeared to be lumpy and dark.
The one-side and one-side end of the printed product is often considered to be insufficient pressure, but it is not. This was the case after the new blanket was installed on the machine. The main reason was that the blanket was not installed properly. Although the rubber upper and lower cleats are arranged in parallel, but the four corners are not at right angles, they become parallelograms; or the distance between the front and back cleats of the rubber is not the same, and it becomes a quadrilateral that is neither parallel nor long and not equal; Equipment. In this way, there is an elastic inconsistency at both ends of the eraser on the same printed surface. The elasticity of the elastic end of the rubber is larger, the elasticity of the tight end is relatively small, and the amount of compression at both ends of the eraser is also not the same, so the printed product has the feeling of a virtual end.
After the machine shuts down, ink suddenly appears in the middle of the printing or the ink is dark in the middle, and the strokes within 30 cm are thickened and ghosted. It may be that the rubber gargle is loose, the screw is not tightened or the yoke tip is worn, or the shaft teeth are not filled with ink. If this is the case with the new eraser, it may also be due to the fact that the rubber drag is too tight.
The new eraser on the machine, product outlets, strokes of different sizes, block thickness uneven, virtual reality, it may be caused by uneven thickness. Broken pens, broken dots, missing dots, or missing paper are of poor quality, such as paper blocks, grass stems, sand, etc. If it is a problem with the plate, let's say something else.
Exclusion method: When installing a new eraser, first measure the length, angle, and radial direction, and cut it into a regular square. Drilling is an important part of the process. Mark the line and make it correct. The four corners must be perpendicular to each other. If the eyes are closed, the splint will not be properly installed. If the rubber is not installed well, in order to save time, use adjustment pressure to solve, it will lead to a variety of contradictions, such as the center distance between the two ends of the drum, the pressure of the rubber deformation greatly shortens the rubber life, to accelerate the sleeve wear.
Eraser and rubber should be paid attention to whether the upper and lower braces are intact and the shaft teeth should be cleaned. Every time the rubber is used, it must be tightened. Use your finger to stretch it.
When replacing the rubber, it should be replaced with cloth and liner paper at the same time. The liner paper should be smooth and smooth. Also check if the pressure of the three rollers is reasonable. Adjust the pressure, press the rubber for one minute, then draw the map with semi-pressure and compaction plots, and fill the low spots with 28~35g/m2 paper to get the ideal flat printing surface. The cut cannot be resolved by increasing the pressure.
Second, the pressure caused by irrational printing failure Pressing cylinder pressure is too large, it will cause pressure rubber, rubber cloth slipped off, serious. The rubber patch is a piece of this one; the network is enlarged, the level of the original is lost at the level of high and low levels; the peeling angle is large, and the india plot is easy to peel and other faults. When the excess pressure is less than zero, the embossing roller sticks to the ink. Paper wrinkles tend to wrinkle.
Impression cylinder pressure is too small, the product ink is not printed. Loss of outlets, broken pens and broken paintings, the entire printing surface is empty.
Excessive pressure on the plate cylinder and the blanket cylinder will cause the printing plate and the text to gradually wear out, and the printing plate will emit light. In severe cases, only one printing plate will be printed with only a few thousand impressions. There will also be fuzzing of the product. When the ink is large, the dots will be enlarged and the lines will be thicker.
The pressure of the plate cylinder and the blanket cylinder is too low. îƒ¨î‰ˆé—¶îž æ´¹ 1. Drive the 鹌㩠鹌㩠summer î¹ î¹ 5  H ç»»î»ç¬•        quietly. 哟蟪瞿î¾æµšîƒ™ 岢鱿 岢鱿 岢鱿 î™å¦«îƒ‘竽î±èž…嫔 î™å¦«îƒ‘竽î±èž…嫔    ズ ズ ズ ズ ズ ズ ズ ズ ズ ズ ズ ズ ズ ズ ズThe pressure of the printing cylinder and the blanket cylinder is too large. Firstly, it can be seen from the eraser that the rubber is white and the surface of the eraser is dark under normal conditions. This is because the ink on the eraser is completely absorbed by the paper under heavy pressure, and the paper is white because it is left with a lot of paper hair. When printing thin paper, it can be seen from the reverse side of the product that the shadow is more serious.
The pressure of the blanket cylinder and the impression cylinder is too small, and the surface of the rubber is dark. This is because the ink is not completely transferred, and the rubber tug even has a water film.
How much is the pressure between the blanket cylinder and the plate cylinder and the impression cylinder reasonable? The author thinks that the neutral blanket rubber cylinder and the plate cylinder are suitable for the compression of 0.08mm, the blanket cylinder and the impression cylinder The compression of 0.08mm plus a piece of printing paper is the ideal pressure. If white paper is printed, it is best to increase the center distance between the impression cylinder and the blanket cylinder. Some operators use the reduced rubber pad to add printing plate whitening method. This changes the ink transfer coefficient of the ink roller to the printing plate, and also increases the friction force of the ink roller on the printing plate. In short, it has many advantages and disadvantages.
The method of adjustment is: in the absence of instrument and gauge measurement, according to the standard liner parameters specified by each machine, minus 0.15mm (ie, two sheets of 80g/m2 paper thickness) equipped with a rubber roller, with the same paper cut Two 40mm wide paper strips are placed at about 10~15cm from the end of the blanket cylinder at both ends, and then the table is pressed. Pull a piece of paper hard, but you can't break it. After the tension on both ends of the paper is reached, remove the rubber and add 0.15mm thick paper. The pressure of the blanket cylinder and the impression cylinder can be solved by the above method of drawing the paper strip.
The conclusion is that the pressure of the impression cylinder and the blanket cylinder is greater than the pressure of the plate cylinder and the blanket cylinder (ie, one sheet of printing paper). The purpose is to allow the skinned ink to transfer to the product more effectively.
Third, the ink roller is not parallel caused by printing failure Analysis: Inconsistent ink roller is not parallel, overweight or too light can cause printing failure, but the plate roller pressure caused by the size of the more errors.
The ink rollers are not parallel to each other, and the contact surface is definitely inconsistent, so the ink transfer is not normal and uneven.
The four versions are not too heavy or too light, and they are too light for printing plates. The ink on the plate base is not strong, and the water is slightly larger to print quickly. Such as increasing the amount of ink on the ink plate floating, reduce the amount of water will paste version, the general situation will appear large water and ink, and ultimately lead to ink and water imbalance.
Reliance on the version of the roller is too heavy, which affects the life of the printing plate and it is easy to lift the strip of ink. The regenerated version will also be broken by dragging or squeezing, and there will also be ink on the edges of the prints or on the trailing edges. The most serious problem is that the plate is bar-shaped, the fountain solution is weakly acidic, and the fountain solution is strongly acidic.
Exclusion method: Be sure to do the pressure balance between the ink roller, contact surface is about 2 ~ 3mm is appropriate, if the ink roller is olive-shaped best not to use, because it can not balance. Version of roller bar width: new rubber roller 5 ~ 6mm is appropriate, the old plastic stick 4 ~ 5mm is appropriate. Because most of the old rubber rollers are aging, the elasticity is weak and the pressure is not large. Avoid plates from bars. Another version of the collector roller must be slightly lighter than the platen roller, so that the amount of ink on the plate is substantial.
Fourth, the water roller is not parallel to the printing failure caused by the printing ink balance is to improve product quality is the key. If the water rollers are not parallel or if one of the water rollers is not adjusted properly, the ink balance will be affected.
Relying on the edition plate of the water roll is too heavy, it will reverse the string ink, reduce the ink on the printing plate. Relying on the version of the water roller is too light, there is not enough water in the printing plate, the water is small in ink, and the blank space is easy to get dirty. The version of the water roller is too tight against the string of water copper rollers, water is on the water roller and there is no water or water on the plate, and the plate is dirty.
By relying on the version of the water roller, the water copper roller is too light, the water cannot be transported to the printing plate, and the printing plate is dried and dirty. If the amount of ink is reduced, the product ink will not reach saturation.
It is also reasonable for the small water roller to be tight on both sides of the copper roller, which directly affects the water supply to the big water roller.
Excluded methods: Sheung Shui plastic cover, we must strive to tighten the package. After wrapping, it is best to use a piece of paper in order to achieve uniform and consistent up and down.
The method for testing the roll tightness of the water roll is to draw the printing plate against the water roller and repeatedly insert the 0.2 mm thick steel plate at different positions on the plate. Steel inserts must have a certain degree of strength, but not too tight. The water roll is about 6~8mm. Relies on the version of the water roller to rely on the string of water to be slightly loose on the version, so you can reduce or avoid the ink on the version of the water roller, down to the string of water copper roller and small water roller.
The tension of the small water roller against the copper roller of the water bucket can be tested with a 80 g/m2 kraft paper strip. When the small water roller is on the copper roller of the water bucket, the kraft paper strip is pulled upwards, so as to be both strong and continuous. It is best to stop the test with 0.2mm thick steel sheet, and the elasticity of the small water roller on both sides of the copper roller can be basically the same.
V. Printing failure caused by unstable pH value of water bucket solution The pH value of the water bucket solution is too low to counter the attack of the ink on the blank space of the layout. The blank space is easy to get dirty, and it is easy to paste. Increase the amount of water, the version of the water film is too large and weakened ink, the product ink is not full, dull. The physical version has a small blistering appearance and feels unfair.
The pH value of the hopper solution is too high, the layout is refreshing, but it is easy to print, such as reducing the amount of water, the layout will be dirty and dry. This led to both a dirty and a dirty version, shortening the life of the plate.
Suddenly, the water fountain solution caused the layout water film to become smaller and smaller, and the ink was not balanced. PS2101 type offset printing îŒ—î¼ îŒ—î¼ ãœ uranium î…ºîƒ—î‚ é±¿ 鱿 鱿 鱿 銮æ¦è§¯îƒ¯ 銮æ¦è§¯îƒ¯ 銮æ¦è§¯îƒ¯ 銮æ¦è§¯îƒ¯ (4) Song  æŽ âˆ· 9 9 9 9 9 9 9 9. The instrument measures the pH and is preferably controlled between 3.6 and 4.5. If there is no instrument detection, according to the author's experience, the water bucket solution (wetting powder) can be prepared in the following ratio: 1:200 (water). But this is not an absolute standard ratio. The specific situation should be treated specifically, so that reasonable preparation. To achieve this, we must look at three: a look at the layout of the water film size, two to see whether the product is full of ink and layout clean, three to see whether the product is not flat paper roll angle. General new version on the machine, version of the sand on the lossless, can not see the water film, the layout was grayish brown, no light, hand touch the blank area with a moist feeling, the layout is clean and dirty, pH value of the water bucket solution is reasonable. After it was printed on 20,000 pages, the screen surface appeared bright and water film appeared, but it was not dirty. The ink was full and even and normal. The paper was not curled and the pH of the water bucket solution was a reasonable value. On the contrary, the layout of the water film is large, paste version, after the shutdown treatment and re-appeared paste, which is the pH value is too small, to increase the solution dose. If the water film is not visible on the layout, the ink color of the product will be gradually reduced from the original saturated state or the pattern will appear. This proves that the pH value of the water bucket solution is too high and must be diluted with clear water. In addition, the water fountain solution must maintain a certain amount, uniform water supply, ink and water can maintain balance.