Storage of four-color printing semi-finished products

In the offset printing process, for the single-color and two-color offset printing machines, the storage requirements for the semi-finished products that are overprinted by the four-color printing are that the color registration can be smoothly performed, and the paper deformation and the printing cannot be avoided due to improper storage. Dirty and other defects on the back. In order to ensure the quality of semi-finished products, it is beneficial to the accuracy of overprinting of the following colors. In the actual work, the following aspects must be done in the storage of semi-finished products:
The delivery and stacking paper should be kept in order. The offset printing delivery system requires the parts to run normally. The paper needs to be neat and tidy, because the unevenly picked paper and the exposed edge of the paper will absorb moisture or moisture. Can cause paper deformation, resulting in the next color overprint is not accurate. In addition, the delivery is not neat, messy, unsightly, paper edge is easy to be folded, torn, resulting in paper failure and waste pages.
In the offset printing process, due to the fact that the offset mechanism of the offset printing press is used to block paper from front to back, paper feed teeth, paper brakes are improperly adjusted, and the flatness and flatness of the paper are poor, the offset of the offset press is likely to be caused. , Or even make the paper appear folded angles to print out prints, affect product quality, and to print sheets binding, finishing and clear count statistics and other post-order work to bring a series of troubles.
The quality requirements for the delivery press of the offset printing press are loose, balanced, and flat. There must be no corners, no shredding, no oil debris, and especially printed semi-finished products, which require dragging and nipping, top and bottom positions. Can not be reversed, try to avoid the incident is not neat, messy. Therefore, in daily printing, special persons should pay attention to the situation of receiving paper. If papers with disparate receipts appear, they must be promptly cleaned. When encountering a large number of papers that are not received, adjust the baffle plate and opener on the delivery table. Position, or knock on the paper.
The quality of the piled paper that prints semi-finished products will directly affect whether the printing can proceed smoothly. The stack of paper is flat, homogeneous, and correct. Then the paper feeding will be normal, otherwise, it will not be able to print.
At present, the speed of domestic offset presses is generally 5000-8000 sheets/hour. This requires that there are enough papers on the pile table to meet the needs of the paper feed, and the fast and efficient function of the offset printing press is used. Before the paper is stacked According to the situation of the paper, knocking, paper and other steps, copperplate paper as little as possible to knock less, high copper paper, paper neat, high smoothness, suitable for paper feeding requirements.
The paper stack is used to meet the continuous feeding of paper in the feeder. Therefore, the quality of the paper stack directly affects the effect of the offset printing machine. If the stack is not neat, there are many corners and broken paper in the stack. Misalignment between the top and bottom, etc., can cause problems such as paper feed failures and overprinting. If the quality of printed semi-finished products is good, the paper feeding will be normal, the quality will be stable, and the output will be high. The operator will not be confused when feeding paper. The paper is fed smoothly, the overprint quality is good, and the labor intensity of the operator is also low, so that high output, high quality and low consumption can be achieved. From this point of view, after the semi-finished products are overprinted with one or two colors, the paper stacking work is very important. If it is done well, it can have a multiplier effect.
The quality requirements for stacking paper are: It is very loose, and it is piled together and flat, with no corners, broken or dirty.
Points to note when stacking paper:
1. Printed semi-finished products can not be turned upside down and bite the mouth, when stacking paper must distinguish the bite and drag the tip, to avoid overturning position caused overprint error;
2. Before printing the semi-manufactured products, the number of papers should be as accurate as possible, so that the quantity is accurate, and the incomplete pages, rotten pages, dirty pages, and overprinted incomplete printed sheets are selected;
3. The piled paper needs to be neat, and it must be affixed to the front retaining board and the side blocking board to ensure accurate positioning;
4. Wash your hands and avoid ink and oil stains on your hands.
The use of plastic film to wrap printing semi-finished products offset four-color overprint, preferably a monochrome machine, two-color machine in the shortest time, the printing is completed. The four-color offset printing erroneously mistakenly takes too long, and the paper is affected by the temperature and humidity of the workshop environment, the more pronounced the telescopic deformation, the more unfavorable the overlay accuracy. Printed semi-finished products can be overprinted for a short time due to the large quantity of printed products. They are wrapped with plastic film on paper stacks. The purpose is to avoid and reduce the paper deformation of semi-finished products and to ensure the accuracy of underprinting. .
Because the paper and the uppermost print on the paper basket are directly exposed to the air, especially if there is no air-conditioner in the workshop, the constant temperature and humidity of the paper cannot be controlled; the edges of the paper stack will follow the inside of the workshop. Temperature and humidity change and change, resulting in tight edges or flounces, the printing of the upper part of the semi-finished product is more deformation of the paper, thereby affecting the accuracy of overprinting of the next channel color, and will cause other printing failures. Therefore, in order to improve the accuracy of four-color offset printing, a layer of scrap pages and blotting paper, and then on the basis of the pressure on the wooden cleats.
The offset printing shop should have fewer windows to open, and the glass windows should be sealed. In order to reduce the deformation of semi-finished products and paper edges around the paper basket, paper can also be wrapped with kraft paper, insulating paper, and plastic sleeves to reduce the direct contact between the paper basket and the outside air. In this way, it is conducive to overprinting. In short, if the printed semi-finished products are printed on the machine every few days due to machine repairs, holiday days, etc., or due to weather conditions, the temperature and humidity of the workshop may vary greatly. This can reduce the paper edge of the paper stack by dressing the semi-finished products. Deformation.
Print semi-finished paper stack height control prints Semi-finished paper stack height should be based on the specific printing product conditions, under normal circumstances, full version of the field of crystal, correspondingly, the paper basket should be lower, or use a wooden plywood paper pile Layered stacking to speed up ink blotting drying, especially coated paper, card paper, textured paper and other high-grade paper printing full version, because the paper surface is relatively smooth, the printed sheet should not be stacked too much, can not drag in the case of imprinting, otherwise Indigo prints will overprint dirty or dirty back, resulting in scrap printing semi-finished products.
Therefore, it is not appropriate to stack the paper piles too high for the full version of the printed materials on the ground and clean paper. On the one hand, in order to prevent the printed products from getting dirty, the stacking paper is too high to hinder the drying speed of the ink layer and affect the color registration of the next color ink. Therefore, the paper stack of such a printing sheet should be as small as possible, or the wooden plywood should be used. Stacked layer by layer, shake loose at intervals to help the ink layer oxide conjunctiva dry.
Conversely, for those semi-finished products that do not have large, full-size prints, paper with rough paper and strong ink-absorption properties can be stacked higher without disturbing drying.
At the same time, some semi-finished products have upturned squatting phenomenon. According to the specific situation, the paper can be stacked neatly, or pressing something more on the stack of paper, increasing the pressure to make the paper flat, or before the printing, make necessary knocks on the paper and Le, the printed semi-finished products remain flat, very scratched, in order to achieve accurate positioning when feeding.