First, ensure the clarity of printing
Firstly, the printing plate should be made of wear-resistant, moderately elastic, high-quality materials. The thickness of the same plate should be the same, the thickness of the resin plate should be no less than 4mm, and the rubber plate should be 6~7mm. Regardless of whether it is using a dark film or a handmade knife, the layout must be neat, the pattern should be neat, the depth of the lines should be no less than 3mm, the arrangement of the text patterns should not be overcrowded, the arc should be sleek and uniform, and the straight lines should be straight and smooth. . When printing, the ink should be properly lightened, the ink layer of the ink coating roller should not be too thick, and the pressure of the roller is moderate, so that the printing ink is even and the surface of the ink box has no obvious dent. Do not increase the ink concentration, increase the pressure of the ink roller to improve the printing effect, this will not only not achieve the desired purpose, but will lead to layout paste, printing quality is worse, especially the text is small, the pattern is complex, delicate lines, Overprinting requires a high-precision layout and the disadvantages are even more pronounced; the speed of the printing press cannot be lower than 800 rpm, too low, the ink on the surface of the box is uneven, and there is a phenomenon of exposed bottom. Too fast, the ink is too thick, the layout is easy to blur, but also to prevent paper, paper, etc. into the printing press stick to the plate, if there is a piece of paper sticky, it should be shut down immediately, wipe with a rag and dip in alcohol.
Second, the printing color should be pure, no color difference
The pros and cons of water-based inks are the key to the pure and bright color of carton printing. Therefore, great care must be taken in the selection. There is no significant difference between high-quality inks and color marks. The touch is delicate, thick, and the concentration is suitable to add water or alcohol solvent to dilute without precipitation and agglomeration phenomenon. Stir with a wooden stick and produce no foam. Mix with other inks, and the affinity is good. Solubility, pure ink, no abnormal reaction. On the contrary, it cannot be used.
It is best to print batches at one time when printing, otherwise, the same barrel of ink is used, and color differences also occur. The reason is that the original ink is diluted with water or an alcohol solvent and is not sealed. When 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 can also decompose the ink.
Third, to prevent the overprinting and ghosting of coated whiteboard carton printing
When the coated whiteboard paper is manufactured, the coating liquid used for coating the whiteboard contains glue, and the surface of the high-grade whiteboard paper is coated with a small amount of gloss wax, so when the paperboard with whiteboard is used for printing, the printing plate and the whiteboard paper are printed. There is slippage at the moment of contact. In addition, the pressure of the printing plate is too heavy, the water-based ink is not easy to penetrate, the carton ink after printing is dried slowly, and the continuous operation is performed during the printing. The printing products are piled up on one another and the scratches appear on the box surface to form a double-overprinting ghost.
To solve this problem, the ink should be lightened with ethanol, do not use water, because it is not volatile, is not conducive to the drying of ink; printing pressure is properly reduced, the printing speed should not be too fast, not more than 600 rev / min is appropriate. Before the stacking of printing presses, an exhaust fan or hot air drying box ink is installed.
Fourth, ensure overprint accuracy
The overlay accuracy depends first of all on the precision of the equipment and the adjustment of the feeding section to push the paperboard in parallel. In addition, it is the layout production, assembly and correction. The following is a discussion of overprint accuracy in terms of layout collage.
After the plate is ready, take a piece of 0.5mm thick transparent polypropylene plate, draw a vertical line at the center of its length, and then press the size of the carton to be printed, draw a line with a small stroke to draw the length, height and height of the line, and press the sample or sample box. Production notices stipulate imposition. After positioning the layout, use the pen to draw the line on the edge of the printing plate. After that, the same size plate base prepared in advance is overlaid on the base plate of the well-drawn line, and all edges are accurately traced (for example, three colors can be used to overprint a plate base). ), Finally, press the printing color, and the corresponding printing plate is firmly stuck in the painted position with neoprene. Then use the double-sided adhesive to attach the printing plate to the roller of the printing machine. The center line of the printing plate can be aligned with the centerline of the platen roller of the printing machine. As long as the position of the imposition is accurate and other objective conditions are satisfied, overprinting is accurate.
Fifth, the impact of full version printing on carton strength
We know that when the carton is printed, the corrugated cardboard is formed by the paper guide rollers and the printing roller of the printing machine and is transferred to the grooved portion. After the paperboard is pressed by the roller during the transfer process, the physical properties of the paperboard are changed to varying degrees. Affect the strength of the carton. Full-plate printing is particularly prominent. Compared with no-printing, the cardboard box of the same material has to be reduced in strength by about 30%. Therefore, it is necessary to pay great attention to the production process. The following measures can be taken to ease it:
First, properly adjust the gaps of the paper guide rollers of the printing press so that the paperboard can pass smoothly without deformation (slightly smaller than the thickness of the paperboard 0.1-0.15mm); Second, the pressure of the printing plate can be adjusted to meet the requirement of clear printing. There is no depression in the surface of the box and it can be flattened. Thirdly, the speed of the printing press (1000 rpm/min or more) should be properly increased, so that the board can pass through the printer as soon as possible to reduce the board pressing time.
Sixth, carton leakage version timely reprint
In the actual production, there is no printing machine with a computer calibration device. Due to the operator's negligence, it is difficult to avoid the phenomenon of missing the word. After similar things happen, remedial measures should be taken promptly. If you only slot and cut corners, you can unload the slotted knife, subsidize the missing layout to the corresponding position, and then remove the other nozzle plate to start the reprint, but avoid the speed too fast, otherwise it will cause Overprinting effect is poor or layout moves. If the printed carton has been nailed, in addition to the layout processed in accordance with the above method, but also adjust the guide roller gap to the shape of the carton after the smooth deformation is not appropriate, the print roller pressure should be properly adjusted, and then transferred to paper Partial baffles determine the position of the layout, and are transported individually during printing.
Seven, thin cardboard printing matters needing attention
The so-called thin cardboard, that is, D, E fine corrugated cardboard, these thin cardboard after the printing of the application of flat pressure die-cutting machine stamping, due to small quantities or customers only once, coupled with the high cost of die-cutting knife, so when the production Use print slotting instead. In actual operation, because the paperboard is too thin, the printing speed must be slowed down, but the paper feeding device is not difficult to push paper, that is to push multiple paperboards at the same time into the printing press, resulting in a lot of waste. To solve this problem, you can use a single machine to slot, then print after binding and forming, but according to the two sides of the carton, different loading plates must be printed twice to complete a complete layout of the carton.
Eight, warpage cardboard to prevent running version, slotted go
The warped cardboard printing adopts single sheet feeding, low-speed operation, and appropriate adjustment of the amount of suction, according to the layout of the layout, slotting in time to move the printing plate groove phase forward and backward correction. The cardboard with serious warpage is selected, and the 3-5 sheets of positive and negative stacking are flattened and reprinted with the weights next time, or folded in the opposite direction of the warp along the indentation line.
In short, actual production encounters specific conditions and must be handled flexibly according to objective conditions. The above is for reference only, because the author's level is certainly limited, and is willing to discuss with peers.
