Ensure the clarity of printing
First of all, the printing plate should be made of wear-resistant, moderately elastic and high-quality materials. The thickness of the plate on the same plate should be the same. The thickness of the resin plate should not be less than 4mm. The rubber plate should be 6mm ~ 7mm. Whether it is filmed with negative film or laser engraved, the layout must be neat, the depth of the text, patterns and lines is not less than 3mm, the arrangement of the text patterns should not be overcrowded, the arcs should be smooth, the thickness should be uniform, and the straight lines should be straight and smooth .
When printing, the ink should be lightened properly, the ink layer of the inking roller should not be too thick, and the pressure of the roller should be moderate, so that the printing ink is uniform, and the box surface has no obvious dents. Never increase the ink concentration and increase the pressure of the inking roller to improve the printing effect. This not only fails to achieve the desired purpose, but also results in paste ink in the area of ​​the plate, and the printing quality is worse, especially for small text, complex patterns, delicate lines, and overprinting requirements. The disadvantage of the high-precision layout is more obvious; the speed of the printing machine cannot be less than 800r / min, the ink on the too low surface is uneven, and the bottom is exposed. Too fast, the ink is too thick, the layout is easy to blur, and at the same time, prevent paper wool, paper scraps, etc. from entering the printing machine and sticking to the printing plate. If you find paper scraps sticking to the plate, stop immediately and wipe clean with a cloth dipped in alcohol.
The printing color should be pure, no color difference in batch
The quality of water-based ink is the key to the pure and bright color of carton printing, so pay great attention to the selection. There is no obvious difference between the high-quality ink and the color standard, the hand feels delicate and sticky, the concentration is suitable for dilution with water or alcohol solvent without precipitation, caking, stirring with a wooden stick without foaming, mixing with other inks, color matching, good affinity, all in all Dissolve phenomenon, the ink color is pure, no abnormal reaction. Otherwise, it cannot be used.
When printing, it is best to print in batches at one time, otherwise, even if the same barrel of ink is used, there will be color difference. The reason is that the original ink is not sealed after being diluted with water or alcohol solvent, and it is exposed to the air for a long time. The chemical components in the ink react with the oxygen in the air, that is, the pigment is reduced, and the strong light also decomposes the ink.
Prevent overprinting and ghosting during printing on coated whiteboard cartons
During the manufacture of coated whiteboard paper, the coating solution used to coat the whiteboard contains a certain amount of glue, and a small amount of glazing wax needs to be applied to the surface of the high-grade whiteboard paper. There is a slippage at the moment of contact with the whiteboard. In addition, the pressure of the printing plate is too heavy, the water-based ink is not easy to penetrate, the ink in the carton after printing is slow to dry, and the continuous operation during printing, the printed products are stacked and stacked, and the double-print ghost image formed by the scratches appears on the surface of the box.
To solve this problem, the ink should be lightened with ethanol, and do not use water, because it is not easy to volatilize, which is not conducive to the drying of the ink; the printing pressure should be appropriately reduced, and the printing speed should not be too fast, and should not exceed 600r / min. Before the stacking of the printing machine, install an exhaust fan or hot air to dry the ink on the surface of the box.
Ensure overprint accuracy
The accuracy of overprinting depends first on the precision of the equipment and whether the adjustment of the paper pusher in the paper feed section is parallel, and then the layout production, assembly and correction. Let's talk about the accuracy of overprinting in terms of layout collage.
After the printing plate is completed, take a 0.5mm thick transparent polypropylene base, draw a vertical line at the center of its length, and then draw a long, wide, and high line with a small pen according to the specifications of the carton to be printed, and then press the sample or the sample box. The production notice specifies imposition. After positioning the layout, draw a line with the edge of the printing plate with a pen, then cover the same size of the prepared base in advance, and accurately draw all the edges (such as overprinting three colors, you can draw another block of the base) ), And finally press the color of the set to stick the corresponding printing plate firmly with neoprene in the drawn position. Then use double-sided tape to attach the printing plate to the roller of the printing machine. The center line of the base and the center line of the roller of the printing machine can be aligned and aligned. As long as the imposition position is accurate and other objective conditions are met, the overprint is accurate.
Effect of full-page printing on carton strength
We know that when carton printing, corrugated cardboard is transferred to the slotted part through the paper guide rollers and printing rollers of the printing machine. After the cardboard is subjected to the pressure of the rollers during the transfer process, the physical properties of the cardboard have changed in different procedures. Affect the strength of the carton. It is particularly prominent during full-page printing. The carton of the same material has a strength reduced by about 30% compared to the carton without printing. Therefore, great attention should be paid to the production process, and the following measures can be taken to alleviate:
1. Properly adjust the gap between the paper guide rollers of the printing machine so that the corrugated cardboard passes smoothly without deformation (slightly smaller than the cardboard thickness of 0.1mm ~ 0.15mm is best);
2. The pressure of the printing plate can be adjusted to meet the requirements of clear printing. The surface of the box has no dents and can be smooth; thirdly, the speed of the printing machine (more than 1000r / min) should be appropriately increased to make the cardboard pass through the printing machine as soon as possible and reduce the time of cardboard compression .
Carton box missing edition timely reprint
In the actual production of printing machines without computer proofreading devices, it is difficult to avoid the phenomenon of missed edition due to the negligence of the operator. After similar things happen, remedial measures should be taken in time. If only the slotting and cutting corners have not been nailed, you can remove the slotting knife, or remove the slotting part, subsidize the missing layout to the corresponding position, and then remove the other mark printing plates to start reprinting, but do not avoid The speed of the vehicle is too fast, otherwise the printing effect will be poor or the layout will be out of position. If the printed carton has been nailed and formed, in addition to the layout as described above, it is also necessary to adjust the gap of each guide roller until the carton passes smoothly after deformation without deformation. The pressure of the printing roller should also be adjusted appropriately, and then the paper feed section is adjusted. The baffle plate determines the position of the layout and is conveyed individually during printing.
Precautions for printing on thin cardboard
The so-called thin cardboard, that is, D, E fine corrugated cardboard, these thin cardboards should be stamped and formed by a flat press die-cutting machine after printing. Because the batch is small or the customer only makes it once, and the cost of the die-cutting knife plate is high, so the production is Switch to printing and slotting. In actual operation, because the cardboard is too thin, the printing speed must be slowed, but the paper pusher is either difficult to push the paper, or push multiple sheets of cardboard into the printing machine at the same time, causing a lot of waste. To solve this problem, a single machine can be used for slotting, binding and forming, and then printing. It is only necessary to install the plate according to the two positive sides of the carton. It takes two times to print a complete carton.
Warping cardboard to prevent running out of the board, slotting
For warped cardboard printing, a single sheet feed is used, running at a low speed, and at the same time appropriately adjusting the amount of air suction, and according to the layout and slotting situation, the slotted phase of the printing plate is jogged in order to correct in reverse. The cardboard with severe warpage is selected, and every 3 to 5 sheets of positive and negative stacking will be flattened with a heavy object and printed again next time, or it will be folded and printed in the opposite direction of the warpage along the indentation line.
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