1. Roller lining and pressure adjustment
When printing white paper, the center distance between the plate cylinder and the rubber cylinder is the same. Just adjust the center of the impression cylinder and the rubber cylinder. When printing 250-450g / m2 whiteboard paper, the center distance of the cylinder can be increased by 0.20-0.4mm. Due to the poor smoothness and roughness of whiteboard paper, the tightness of the paper is not as good as that of coated paper. When printing whiteboard paper, pay attention to the pressure of printing.
If printing 400g / m2 of whiteboard paper, the gap between the plate cylinder and the rubber cylinder is 3.95mm, the gap between the rubber cylinder and the impression cylinder is 3.40mm, the total package of the plate cylinder is 0.65-0.75mm, the total rubber cylinder The liner is 3.15-3.35mm (measured with a micrometer). If the paper changes from thick to thin, the reduced thickness, that is, the thickness of the liner drawn from the plate liner should be added to the rubber cylinder. If the paper changes from thin to thick, subtract a certain thickness from the rubber cylinder liner and add the corresponding thickness to the plate cylinder liner.
2. Adjustment of the offset paper feeding part
1. When printing on whiteboard paper, the air volume of the paper suction nozzle and the paper blowing nozzle of the paper feeding part should be adjusted accordingly.
2. The paper-separating nozzle and paper-feeding nozzle should be replaced with larger diameter and thicker rubber apron. The tension gauge pressure spring can be replaced with a steel wire with a diameter of 1.5mm; by removing the gap between the feed roller cam and its shaft Connect the pin, or remove the roller on the swing lever to achieve the purpose of no swing of the paper feed roller and stable paper feeding.
3. When printing white paper, the double-sheet control or the gap of the offset press should be increased accordingly; the distance between the pressure tongue of the side gauge and the front gauge and the paperboard, and the distance between the safety bar and the paperboard should be Increase some.
4. The distance between the delivery tooth pad and the surface of the impression cylinder and the delivery tooth pad and the paperboard should be increased, and the distance should be kept equal to the paper thickness plus 0.3mm.
3. Color sequence arrangement during printing
1. The products printed on whiteboard have Hong Kong version on the ground, and also have text, lines and patterns. Such as: express mail envelopes, wine boxes, cigarette case outer packaging (bars) and other printed products of the postal department, the color sequence of the printing is preferably to print the text, lines, patterns, and then put the full version on the ground and finally print on the machine In this way, it can avoid the phenomenon of dirt and rubbing caused by the paper colliding with each other when the imprint is not dry due to the thick whiteboard paper, and the back side is sticky.
2. Put the dark color on the front and the light color on the back. Because the dark color ink has strong hiding power and strong adhesion, it is printed on the front to facilitate accurate overprinting; the light color ink has weak hiding power. It is not easy to observe the rules when it is placed on the back to print the volume. The effect of overprinting is much better.
3. Often in a printed product, there are halftone four-color electronic points, and there are continuous adjustment patterns, text, and lines. The four-color electrical branch should be printed first, which is helpful for accurate overprinting and reduces the impact of paper expansion and contraction. Then print the continuous adjustment patterns, text, and lines. In the arrangement of the printing color sequence, it is necessary to identify the primary and secondary order, which is more appropriate after the difficulty.
4. If the weather is hot, when the white paper is printed in monochrome, if the paper has uneven moisture content, uneven wrinkling, poor surface strength, etc., causing powder loss and hair loss, you can also first print a blank water, you can Solve the phenomenon.
4. How to prevent white paper from sticking
1. Use the original barrel ink as much as possible when printing on the ground, do not add 6 # ink, and add some debonding agent and anti-sticking agent; do not add dry oil when the weather is hot.
The printed version of the field is often prone to sticky dirt on the back. It is often solved by powder spraying. Although the printing anti-sticking powder spray contains pure plant materials, the dispersibility and fluidity are good, but the use of powder spray will directly affect the printing product. The surface gloss makes the ink color not bright, and pollutes the environment, and has an impact on the accuracy of the offset press.
2. The surface of whiteboard paper is rough, the quality is loose, the ink absorption is large, and the flatness is poor. Therefore, when printing the full version on the ground, the background color should be printed first, and then the dark color. The background color should be darkened and printed thin. Big. If the flatness of the whiteboard paper is good, then print the dark color first when printing the full field, and the ink volume is sufficient, based on the back is not sticky, and then overprint the background color thinly, so that the printed product will have a smoother finish Well, at the same time, pay attention to the balance of water and ink, and control the moisture content of the printing plate.
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